diff options
Diffstat (limited to 'arch/x86/kvm/mmu')
| -rw-r--r-- | arch/x86/kvm/mmu/mmu.c | 6961 | ||||
| -rw-r--r-- | arch/x86/kvm/mmu/mmu_internal.h | 320 | ||||
| -rw-r--r-- | arch/x86/kvm/mmu/mmutrace.h | 451 | ||||
| -rw-r--r-- | arch/x86/kvm/mmu/page_track.c | 302 | ||||
| -rw-r--r-- | arch/x86/kvm/mmu/paging_tmpl.h | 1116 | ||||
| -rw-r--r-- | arch/x86/kvm/mmu/spte.c | 507 | ||||
| -rw-r--r-- | arch/x86/kvm/mmu/spte.h | 474 | ||||
| -rw-r--r-- | arch/x86/kvm/mmu/tdp_iter.c | 180 | ||||
| -rw-r--r-- | arch/x86/kvm/mmu/tdp_iter.h | 118 | ||||
| -rw-r--r-- | arch/x86/kvm/mmu/tdp_mmu.c | 1885 | ||||
| -rw-r--r-- | arch/x86/kvm/mmu/tdp_mmu.h | 95 |
11 files changed, 12409 insertions, 0 deletions
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c new file mode 100644 index 000000000..d30325e29 --- /dev/null +++ b/arch/x86/kvm/mmu/mmu.c @@ -0,0 +1,6961 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Kernel-based Virtual Machine driver for Linux + * + * This module enables machines with Intel VT-x extensions to run virtual + * machines without emulation or binary translation. + * + * MMU support + * + * Copyright (C) 2006 Qumranet, Inc. + * Copyright 2010 Red Hat, Inc. and/or its affiliates. + * + * Authors: + * Yaniv Kamay <yaniv@qumranet.com> + * Avi Kivity <avi@qumranet.com> + */ + +#include "irq.h" +#include "ioapic.h" +#include "mmu.h" +#include "mmu_internal.h" +#include "tdp_mmu.h" +#include "x86.h" +#include "kvm_cache_regs.h" +#include "kvm_emulate.h" +#include "cpuid.h" +#include "spte.h" + +#include <linux/kvm_host.h> +#include <linux/types.h> +#include <linux/string.h> +#include <linux/mm.h> +#include <linux/highmem.h> +#include <linux/moduleparam.h> +#include <linux/export.h> +#include <linux/swap.h> +#include <linux/hugetlb.h> +#include <linux/compiler.h> +#include <linux/srcu.h> +#include <linux/slab.h> +#include <linux/sched/signal.h> +#include <linux/uaccess.h> +#include <linux/hash.h> +#include <linux/kern_levels.h> +#include <linux/kstrtox.h> +#include <linux/kthread.h> + +#include <asm/page.h> +#include <asm/memtype.h> +#include <asm/cmpxchg.h> +#include <asm/io.h> +#include <asm/set_memory.h> +#include <asm/vmx.h> +#include <asm/kvm_page_track.h> +#include "trace.h" + +extern bool itlb_multihit_kvm_mitigation; + +static bool nx_hugepage_mitigation_hard_disabled; + +int __read_mostly nx_huge_pages = -1; +static uint __read_mostly nx_huge_pages_recovery_period_ms; +#ifdef CONFIG_PREEMPT_RT +/* Recovery can cause latency spikes, disable it for PREEMPT_RT. */ +static uint __read_mostly nx_huge_pages_recovery_ratio = 0; +#else +static uint __read_mostly nx_huge_pages_recovery_ratio = 60; +#endif + +static int get_nx_huge_pages(char *buffer, const struct kernel_param *kp); +static int set_nx_huge_pages(const char *val, const struct kernel_param *kp); +static int set_nx_huge_pages_recovery_param(const char *val, const struct kernel_param *kp); + +static const struct kernel_param_ops nx_huge_pages_ops = { + .set = set_nx_huge_pages, + .get = get_nx_huge_pages, +}; + +static const struct kernel_param_ops nx_huge_pages_recovery_param_ops = { + .set = set_nx_huge_pages_recovery_param, + .get = param_get_uint, +}; + +module_param_cb(nx_huge_pages, &nx_huge_pages_ops, &nx_huge_pages, 0644); +__MODULE_PARM_TYPE(nx_huge_pages, "bool"); +module_param_cb(nx_huge_pages_recovery_ratio, &nx_huge_pages_recovery_param_ops, + &nx_huge_pages_recovery_ratio, 0644); +__MODULE_PARM_TYPE(nx_huge_pages_recovery_ratio, "uint"); +module_param_cb(nx_huge_pages_recovery_period_ms, &nx_huge_pages_recovery_param_ops, + &nx_huge_pages_recovery_period_ms, 0644); +__MODULE_PARM_TYPE(nx_huge_pages_recovery_period_ms, "uint"); + +static bool __read_mostly force_flush_and_sync_on_reuse; +module_param_named(flush_on_reuse, force_flush_and_sync_on_reuse, bool, 0644); + +/* + * When setting this variable to true it enables Two-Dimensional-Paging + * where the hardware walks 2 page tables: + * 1. the guest-virtual to guest-physical + * 2. while doing 1. it walks guest-physical to host-physical + * If the hardware supports that we don't need to do shadow paging. + */ +bool tdp_enabled = false; + +static int max_huge_page_level __read_mostly; +static int tdp_root_level __read_mostly; +static int max_tdp_level __read_mostly; + +#ifdef MMU_DEBUG +bool dbg = 0; +module_param(dbg, bool, 0644); +#endif + +#define PTE_PREFETCH_NUM 8 + +#include <trace/events/kvm.h> + +/* make pte_list_desc fit well in cache lines */ +#define PTE_LIST_EXT 14 + +/* + * Slight optimization of cacheline layout, by putting `more' and `spte_count' + * at the start; then accessing it will only use one single cacheline for + * either full (entries==PTE_LIST_EXT) case or entries<=6. + */ +struct pte_list_desc { + struct pte_list_desc *more; + /* + * Stores number of entries stored in the pte_list_desc. No need to be + * u64 but just for easier alignment. When PTE_LIST_EXT, means full. + */ + u64 spte_count; + u64 *sptes[PTE_LIST_EXT]; +}; + +struct kvm_shadow_walk_iterator { + u64 addr; + hpa_t shadow_addr; + u64 *sptep; + int level; + unsigned index; +}; + +#define for_each_shadow_entry_using_root(_vcpu, _root, _addr, _walker) \ + for (shadow_walk_init_using_root(&(_walker), (_vcpu), \ + (_root), (_addr)); \ + shadow_walk_okay(&(_walker)); \ + shadow_walk_next(&(_walker))) + +#define for_each_shadow_entry(_vcpu, _addr, _walker) \ + for (shadow_walk_init(&(_walker), _vcpu, _addr); \ + shadow_walk_okay(&(_walker)); \ + shadow_walk_next(&(_walker))) + +#define for_each_shadow_entry_lockless(_vcpu, _addr, _walker, spte) \ + for (shadow_walk_init(&(_walker), _vcpu, _addr); \ + shadow_walk_okay(&(_walker)) && \ + ({ spte = mmu_spte_get_lockless(_walker.sptep); 1; }); \ + __shadow_walk_next(&(_walker), spte)) + +static struct kmem_cache *pte_list_desc_cache; +struct kmem_cache *mmu_page_header_cache; +static struct percpu_counter kvm_total_used_mmu_pages; + +static void mmu_spte_set(u64 *sptep, u64 spte); + +struct kvm_mmu_role_regs { + const unsigned long cr0; + const unsigned long cr4; + const u64 efer; +}; + +#define CREATE_TRACE_POINTS +#include "mmutrace.h" + +/* + * Yes, lot's of underscores. They're a hint that you probably shouldn't be + * reading from the role_regs. Once the root_role is constructed, it becomes + * the single source of truth for the MMU's state. + */ +#define BUILD_MMU_ROLE_REGS_ACCESSOR(reg, name, flag) \ +static inline bool __maybe_unused \ +____is_##reg##_##name(const struct kvm_mmu_role_regs *regs) \ +{ \ + return !!(regs->reg & flag); \ +} +BUILD_MMU_ROLE_REGS_ACCESSOR(cr0, pg, X86_CR0_PG); +BUILD_MMU_ROLE_REGS_ACCESSOR(cr0, wp, X86_CR0_WP); +BUILD_MMU_ROLE_REGS_ACCESSOR(cr4, pse, X86_CR4_PSE); +BUILD_MMU_ROLE_REGS_ACCESSOR(cr4, pae, X86_CR4_PAE); +BUILD_MMU_ROLE_REGS_ACCESSOR(cr4, smep, X86_CR4_SMEP); +BUILD_MMU_ROLE_REGS_ACCESSOR(cr4, smap, X86_CR4_SMAP); +BUILD_MMU_ROLE_REGS_ACCESSOR(cr4, pke, X86_CR4_PKE); +BUILD_MMU_ROLE_REGS_ACCESSOR(cr4, la57, X86_CR4_LA57); +BUILD_MMU_ROLE_REGS_ACCESSOR(efer, nx, EFER_NX); +BUILD_MMU_ROLE_REGS_ACCESSOR(efer, lma, EFER_LMA); + +/* + * The MMU itself (with a valid role) is the single source of truth for the + * MMU. Do not use the regs used to build the MMU/role, nor the vCPU. The + * regs don't account for dependencies, e.g. clearing CR4 bits if CR0.PG=1, + * and the vCPU may be incorrect/irrelevant. + */ +#define BUILD_MMU_ROLE_ACCESSOR(base_or_ext, reg, name) \ +static inline bool __maybe_unused is_##reg##_##name(struct kvm_mmu *mmu) \ +{ \ + return !!(mmu->cpu_role. base_or_ext . reg##_##name); \ +} +BUILD_MMU_ROLE_ACCESSOR(base, cr0, wp); +BUILD_MMU_ROLE_ACCESSOR(ext, cr4, pse); +BUILD_MMU_ROLE_ACCESSOR(ext, cr4, smep); +BUILD_MMU_ROLE_ACCESSOR(ext, cr4, smap); +BUILD_MMU_ROLE_ACCESSOR(ext, cr4, pke); +BUILD_MMU_ROLE_ACCESSOR(ext, cr4, la57); +BUILD_MMU_ROLE_ACCESSOR(base, efer, nx); +BUILD_MMU_ROLE_ACCESSOR(ext, efer, lma); + +static inline bool is_cr0_pg(struct kvm_mmu *mmu) +{ + return mmu->cpu_role.base.level > 0; +} + +static inline bool is_cr4_pae(struct kvm_mmu *mmu) +{ + return !mmu->cpu_role.base.has_4_byte_gpte; +} + +static struct kvm_mmu_role_regs vcpu_to_role_regs(struct kvm_vcpu *vcpu) +{ + struct kvm_mmu_role_regs regs = { + .cr0 = kvm_read_cr0_bits(vcpu, KVM_MMU_CR0_ROLE_BITS), + .cr4 = kvm_read_cr4_bits(vcpu, KVM_MMU_CR4_ROLE_BITS), + .efer = vcpu->arch.efer, + }; + + return regs; +} + +static unsigned long get_guest_cr3(struct kvm_vcpu *vcpu) +{ + return kvm_read_cr3(vcpu); +} + +static inline unsigned long kvm_mmu_get_guest_pgd(struct kvm_vcpu *vcpu, + struct kvm_mmu *mmu) +{ + if (IS_ENABLED(CONFIG_RETPOLINE) && mmu->get_guest_pgd == get_guest_cr3) + return kvm_read_cr3(vcpu); + + return mmu->get_guest_pgd(vcpu); +} + +static inline bool kvm_available_flush_tlb_with_range(void) +{ + return kvm_x86_ops.tlb_remote_flush_with_range; +} + +static void kvm_flush_remote_tlbs_with_range(struct kvm *kvm, + struct kvm_tlb_range *range) +{ + int ret = -ENOTSUPP; + + if (range && kvm_x86_ops.tlb_remote_flush_with_range) + ret = static_call(kvm_x86_tlb_remote_flush_with_range)(kvm, range); + + if (ret) + kvm_flush_remote_tlbs(kvm); +} + +void kvm_flush_remote_tlbs_with_address(struct kvm *kvm, + u64 start_gfn, u64 pages) +{ + struct kvm_tlb_range range; + + range.start_gfn = start_gfn; + range.pages = pages; + + kvm_flush_remote_tlbs_with_range(kvm, &range); +} + +static void mark_mmio_spte(struct kvm_vcpu *vcpu, u64 *sptep, u64 gfn, + unsigned int access) +{ + u64 spte = make_mmio_spte(vcpu, gfn, access); + + trace_mark_mmio_spte(sptep, gfn, spte); + mmu_spte_set(sptep, spte); +} + +static gfn_t get_mmio_spte_gfn(u64 spte) +{ + u64 gpa = spte & shadow_nonpresent_or_rsvd_lower_gfn_mask; + + gpa |= (spte >> SHADOW_NONPRESENT_OR_RSVD_MASK_LEN) + & shadow_nonpresent_or_rsvd_mask; + + return gpa >> PAGE_SHIFT; +} + +static unsigned get_mmio_spte_access(u64 spte) +{ + return spte & shadow_mmio_access_mask; +} + +static bool check_mmio_spte(struct kvm_vcpu *vcpu, u64 spte) +{ + u64 kvm_gen, spte_gen, gen; + + gen = kvm_vcpu_memslots(vcpu)->generation; + if (unlikely(gen & KVM_MEMSLOT_GEN_UPDATE_IN_PROGRESS)) + return false; + + kvm_gen = gen & MMIO_SPTE_GEN_MASK; + spte_gen = get_mmio_spte_generation(spte); + + trace_check_mmio_spte(spte, kvm_gen, spte_gen); + return likely(kvm_gen == spte_gen); +} + +static int is_cpuid_PSE36(void) +{ + return 1; +} + +#ifdef CONFIG_X86_64 +static void __set_spte(u64 *sptep, u64 spte) +{ + WRITE_ONCE(*sptep, spte); +} + +static void __update_clear_spte_fast(u64 *sptep, u64 spte) +{ + WRITE_ONCE(*sptep, spte); +} + +static u64 __update_clear_spte_slow(u64 *sptep, u64 spte) +{ + return xchg(sptep, spte); +} + +static u64 __get_spte_lockless(u64 *sptep) +{ + return READ_ONCE(*sptep); +} +#else +union split_spte { + struct { + u32 spte_low; + u32 spte_high; + }; + u64 spte; +}; + +static void count_spte_clear(u64 *sptep, u64 spte) +{ + struct kvm_mmu_page *sp = sptep_to_sp(sptep); + + if (is_shadow_present_pte(spte)) + return; + + /* Ensure the spte is completely set before we increase the count */ + smp_wmb(); + sp->clear_spte_count++; +} + +static void __set_spte(u64 *sptep, u64 spte) +{ + union split_spte *ssptep, sspte; + + ssptep = (union split_spte *)sptep; + sspte = (union split_spte)spte; + + ssptep->spte_high = sspte.spte_high; + + /* + * If we map the spte from nonpresent to present, We should store + * the high bits firstly, then set present bit, so cpu can not + * fetch this spte while we are setting the spte. + */ + smp_wmb(); + + WRITE_ONCE(ssptep->spte_low, sspte.spte_low); +} + +static void __update_clear_spte_fast(u64 *sptep, u64 spte) +{ + union split_spte *ssptep, sspte; + + ssptep = (union split_spte *)sptep; + sspte = (union split_spte)spte; + + WRITE_ONCE(ssptep->spte_low, sspte.spte_low); + + /* + * If we map the spte from present to nonpresent, we should clear + * present bit firstly to avoid vcpu fetch the old high bits. + */ + smp_wmb(); + + ssptep->spte_high = sspte.spte_high; + count_spte_clear(sptep, spte); +} + +static u64 __update_clear_spte_slow(u64 *sptep, u64 spte) +{ + union split_spte *ssptep, sspte, orig; + + ssptep = (union split_spte *)sptep; + sspte = (union split_spte)spte; + + /* xchg acts as a barrier before the setting of the high bits */ + orig.spte_low = xchg(&ssptep->spte_low, sspte.spte_low); + orig.spte_high = ssptep->spte_high; + ssptep->spte_high = sspte.spte_high; + count_spte_clear(sptep, spte); + + return orig.spte; +} + +/* + * The idea using the light way get the spte on x86_32 guest is from + * gup_get_pte (mm/gup.c). + * + * An spte tlb flush may be pending, because kvm_set_pte_rmap + * coalesces them and we are running out of the MMU lock. Therefore + * we need to protect against in-progress updates of the spte. + * + * Reading the spte while an update is in progress may get the old value + * for the high part of the spte. The race is fine for a present->non-present + * change (because the high part of the spte is ignored for non-present spte), + * but for a present->present change we must reread the spte. + * + * All such changes are done in two steps (present->non-present and + * non-present->present), hence it is enough to count the number of + * present->non-present updates: if it changed while reading the spte, + * we might have hit the race. This is done using clear_spte_count. + */ +static u64 __get_spte_lockless(u64 *sptep) +{ + struct kvm_mmu_page *sp = sptep_to_sp(sptep); + union split_spte spte, *orig = (union split_spte *)sptep; + int count; + +retry: + count = sp->clear_spte_count; + smp_rmb(); + + spte.spte_low = orig->spte_low; + smp_rmb(); + + spte.spte_high = orig->spte_high; + smp_rmb(); + + if (unlikely(spte.spte_low != orig->spte_low || + count != sp->clear_spte_count)) + goto retry; + + return spte.spte; +} +#endif + +/* Rules for using mmu_spte_set: + * Set the sptep from nonpresent to present. + * Note: the sptep being assigned *must* be either not present + * or in a state where the hardware will not attempt to update + * the spte. + */ +static void mmu_spte_set(u64 *sptep, u64 new_spte) +{ + WARN_ON(is_shadow_present_pte(*sptep)); + __set_spte(sptep, new_spte); +} + +/* + * Update the SPTE (excluding the PFN), but do not track changes in its + * accessed/dirty status. + */ +static u64 mmu_spte_update_no_track(u64 *sptep, u64 new_spte) +{ + u64 old_spte = *sptep; + + WARN_ON(!is_shadow_present_pte(new_spte)); + check_spte_writable_invariants(new_spte); + + if (!is_shadow_present_pte(old_spte)) { + mmu_spte_set(sptep, new_spte); + return old_spte; + } + + if (!spte_has_volatile_bits(old_spte)) + __update_clear_spte_fast(sptep, new_spte); + else + old_spte = __update_clear_spte_slow(sptep, new_spte); + + WARN_ON(spte_to_pfn(old_spte) != spte_to_pfn(new_spte)); + + return old_spte; +} + +/* Rules for using mmu_spte_update: + * Update the state bits, it means the mapped pfn is not changed. + * + * Whenever an MMU-writable SPTE is overwritten with a read-only SPTE, remote + * TLBs must be flushed. Otherwise rmap_write_protect will find a read-only + * spte, even though the writable spte might be cached on a CPU's TLB. + * + * Returns true if the TLB needs to be flushed + */ +static bool mmu_spte_update(u64 *sptep, u64 new_spte) +{ + bool flush = false; + u64 old_spte = mmu_spte_update_no_track(sptep, new_spte); + + if (!is_shadow_present_pte(old_spte)) + return false; + + /* + * For the spte updated out of mmu-lock is safe, since + * we always atomically update it, see the comments in + * spte_has_volatile_bits(). + */ + if (is_mmu_writable_spte(old_spte) && + !is_writable_pte(new_spte)) + flush = true; + + /* + * Flush TLB when accessed/dirty states are changed in the page tables, + * to guarantee consistency between TLB and page tables. + */ + + if (is_accessed_spte(old_spte) && !is_accessed_spte(new_spte)) { + flush = true; + kvm_set_pfn_accessed(spte_to_pfn(old_spte)); + } + + if (is_dirty_spte(old_spte) && !is_dirty_spte(new_spte)) { + flush = true; + kvm_set_pfn_dirty(spte_to_pfn(old_spte)); + } + + return flush; +} + +/* + * Rules for using mmu_spte_clear_track_bits: + * It sets the sptep from present to nonpresent, and track the + * state bits, it is used to clear the last level sptep. + * Returns the old PTE. + */ +static u64 mmu_spte_clear_track_bits(struct kvm *kvm, u64 *sptep) +{ + kvm_pfn_t pfn; + u64 old_spte = *sptep; + int level = sptep_to_sp(sptep)->role.level; + struct page *page; + + if (!is_shadow_present_pte(old_spte) || + !spte_has_volatile_bits(old_spte)) + __update_clear_spte_fast(sptep, 0ull); + else + old_spte = __update_clear_spte_slow(sptep, 0ull); + + if (!is_shadow_present_pte(old_spte)) + return old_spte; + + kvm_update_page_stats(kvm, level, -1); + + pfn = spte_to_pfn(old_spte); + + /* + * KVM doesn't hold a reference to any pages mapped into the guest, and + * instead uses the mmu_notifier to ensure that KVM unmaps any pages + * before they are reclaimed. Sanity check that, if the pfn is backed + * by a refcounted page, the refcount is elevated. + */ + page = kvm_pfn_to_refcounted_page(pfn); + WARN_ON(page && !page_count(page)); + + if (is_accessed_spte(old_spte)) + kvm_set_pfn_accessed(pfn); + + if (is_dirty_spte(old_spte)) + kvm_set_pfn_dirty(pfn); + + return old_spte; +} + +/* + * Rules for using mmu_spte_clear_no_track: + * Directly clear spte without caring the state bits of sptep, + * it is used to set the upper level spte. + */ +static void mmu_spte_clear_no_track(u64 *sptep) +{ + __update_clear_spte_fast(sptep, 0ull); +} + +static u64 mmu_spte_get_lockless(u64 *sptep) +{ + return __get_spte_lockless(sptep); +} + +/* Returns the Accessed status of the PTE and resets it at the same time. */ +static bool mmu_spte_age(u64 *sptep) +{ + u64 spte = mmu_spte_get_lockless(sptep); + + if (!is_accessed_spte(spte)) + return false; + + if (spte_ad_enabled(spte)) { + clear_bit((ffs(shadow_accessed_mask) - 1), + (unsigned long *)sptep); + } else { + /* + * Capture the dirty status of the page, so that it doesn't get + * lost when the SPTE is marked for access tracking. + */ + if (is_writable_pte(spte)) + kvm_set_pfn_dirty(spte_to_pfn(spte)); + + spte = mark_spte_for_access_track(spte); + mmu_spte_update_no_track(sptep, spte); + } + + return true; +} + +static void walk_shadow_page_lockless_begin(struct kvm_vcpu *vcpu) +{ + if (is_tdp_mmu(vcpu->arch.mmu)) { + kvm_tdp_mmu_walk_lockless_begin(); + } else { + /* + * Prevent page table teardown by making any free-er wait during + * kvm_flush_remote_tlbs() IPI to all active vcpus. + */ + local_irq_disable(); + + /* + * Make sure a following spte read is not reordered ahead of the write + * to vcpu->mode. + */ + smp_store_mb(vcpu->mode, READING_SHADOW_PAGE_TABLES); + } +} + +static void walk_shadow_page_lockless_end(struct kvm_vcpu *vcpu) +{ + if (is_tdp_mmu(vcpu->arch.mmu)) { + kvm_tdp_mmu_walk_lockless_end(); + } else { + /* + * Make sure the write to vcpu->mode is not reordered in front of + * reads to sptes. If it does, kvm_mmu_commit_zap_page() can see us + * OUTSIDE_GUEST_MODE and proceed to free the shadow page table. + */ + smp_store_release(&vcpu->mode, OUTSIDE_GUEST_MODE); + local_irq_enable(); + } +} + +static int mmu_topup_memory_caches(struct kvm_vcpu *vcpu, bool maybe_indirect) +{ + int r; + + /* 1 rmap, 1 parent PTE per level, and the prefetched rmaps. */ + r = kvm_mmu_topup_memory_cache(&vcpu->arch.mmu_pte_list_desc_cache, + 1 + PT64_ROOT_MAX_LEVEL + PTE_PREFETCH_NUM); + if (r) + return r; + r = kvm_mmu_topup_memory_cache(&vcpu->arch.mmu_shadow_page_cache, + PT64_ROOT_MAX_LEVEL); + if (r) + return r; + if (maybe_indirect) { + r = kvm_mmu_topup_memory_cache(&vcpu->arch.mmu_shadowed_info_cache, + PT64_ROOT_MAX_LEVEL); + if (r) + return r; + } + return kvm_mmu_topup_memory_cache(&vcpu->arch.mmu_page_header_cache, + PT64_ROOT_MAX_LEVEL); +} + +static void mmu_free_memory_caches(struct kvm_vcpu *vcpu) +{ + kvm_mmu_free_memory_cache(&vcpu->arch.mmu_pte_list_desc_cache); + kvm_mmu_free_memory_cache(&vcpu->arch.mmu_shadow_page_cache); + kvm_mmu_free_memory_cache(&vcpu->arch.mmu_shadowed_info_cache); + kvm_mmu_free_memory_cache(&vcpu->arch.mmu_page_header_cache); +} + +static void mmu_free_pte_list_desc(struct pte_list_desc *pte_list_desc) +{ + kmem_cache_free(pte_list_desc_cache, pte_list_desc); +} + +static bool sp_has_gptes(struct kvm_mmu_page *sp); + +static gfn_t kvm_mmu_page_get_gfn(struct kvm_mmu_page *sp, int index) +{ + if (sp->role.passthrough) + return sp->gfn; + + if (!sp->role.direct) + return sp->shadowed_translation[index] >> PAGE_SHIFT; + + return sp->gfn + (index << ((sp->role.level - 1) * SPTE_LEVEL_BITS)); +} + +/* + * For leaf SPTEs, fetch the *guest* access permissions being shadowed. Note + * that the SPTE itself may have a more constrained access permissions that + * what the guest enforces. For example, a guest may create an executable + * huge PTE but KVM may disallow execution to mitigate iTLB multihit. + */ +static u32 kvm_mmu_page_get_access(struct kvm_mmu_page *sp, int index) +{ + if (sp_has_gptes(sp)) + return sp->shadowed_translation[index] & ACC_ALL; + + /* + * For direct MMUs (e.g. TDP or non-paging guests) or passthrough SPs, + * KVM is not shadowing any guest page tables, so the "guest access + * permissions" are just ACC_ALL. + * + * For direct SPs in indirect MMUs (shadow paging), i.e. when KVM + * is shadowing a guest huge page with small pages, the guest access + * permissions being shadowed are the access permissions of the huge + * page. + * + * In both cases, sp->role.access contains the correct access bits. + */ + return sp->role.access; +} + +static void kvm_mmu_page_set_translation(struct kvm_mmu_page *sp, int index, + gfn_t gfn, unsigned int access) +{ + if (sp_has_gptes(sp)) { + sp->shadowed_translation[index] = (gfn << PAGE_SHIFT) | access; + return; + } + + WARN_ONCE(access != kvm_mmu_page_get_access(sp, index), + "access mismatch under %s page %llx (expected %u, got %u)\n", + sp->role.passthrough ? "passthrough" : "direct", + sp->gfn, kvm_mmu_page_get_access(sp, index), access); + + WARN_ONCE(gfn != kvm_mmu_page_get_gfn(sp, index), + "gfn mismatch under %s page %llx (expected %llx, got %llx)\n", + sp->role.passthrough ? "passthrough" : "direct", + sp->gfn, kvm_mmu_page_get_gfn(sp, index), gfn); +} + +static void kvm_mmu_page_set_access(struct kvm_mmu_page *sp, int index, + unsigned int access) +{ + gfn_t gfn = kvm_mmu_page_get_gfn(sp, index); + + kvm_mmu_page_set_translation(sp, index, gfn, access); +} + +/* + * Return the pointer to the large page information for a given gfn, + * handling slots that are not large page aligned. + */ +static struct kvm_lpage_info *lpage_info_slot(gfn_t gfn, + const struct kvm_memory_slot *slot, int level) +{ + unsigned long idx; + + idx = gfn_to_index(gfn, slot->base_gfn, level); + return &slot->arch.lpage_info[level - 2][idx]; +} + +static void update_gfn_disallow_lpage_count(const struct kvm_memory_slot *slot, + gfn_t gfn, int count) +{ + struct kvm_lpage_info *linfo; + int i; + + for (i = PG_LEVEL_2M; i <= KVM_MAX_HUGEPAGE_LEVEL; ++i) { + linfo = lpage_info_slot(gfn, slot, i); + linfo->disallow_lpage += count; + WARN_ON(linfo->disallow_lpage < 0); + } +} + +void kvm_mmu_gfn_disallow_lpage(const struct kvm_memory_slot *slot, gfn_t gfn) +{ + update_gfn_disallow_lpage_count(slot, gfn, 1); +} + +void kvm_mmu_gfn_allow_lpage(const struct kvm_memory_slot *slot, gfn_t gfn) +{ + update_gfn_disallow_lpage_count(slot, gfn, -1); +} + +static void account_shadowed(struct kvm *kvm, struct kvm_mmu_page *sp) +{ + struct kvm_memslots *slots; + struct kvm_memory_slot *slot; + gfn_t gfn; + + kvm->arch.indirect_shadow_pages++; + gfn = sp->gfn; + slots = kvm_memslots_for_spte_role(kvm, sp->role); + slot = __gfn_to_memslot(slots, gfn); + + /* the non-leaf shadow pages are keeping readonly. */ + if (sp->role.level > PG_LEVEL_4K) + return kvm_slot_page_track_add_page(kvm, slot, gfn, + KVM_PAGE_TRACK_WRITE); + + kvm_mmu_gfn_disallow_lpage(slot, gfn); + + if (kvm_mmu_slot_gfn_write_protect(kvm, slot, gfn, PG_LEVEL_4K)) + kvm_flush_remote_tlbs_with_address(kvm, gfn, 1); +} + +void account_huge_nx_page(struct kvm *kvm, struct kvm_mmu_page *sp) +{ + if (sp->lpage_disallowed) + return; + + ++kvm->stat.nx_lpage_splits; + list_add_tail(&sp->lpage_disallowed_link, + &kvm->arch.lpage_disallowed_mmu_pages); + sp->lpage_disallowed = true; +} + +static void unaccount_shadowed(struct kvm *kvm, struct kvm_mmu_page *sp) +{ + struct kvm_memslots *slots; + struct kvm_memory_slot *slot; + gfn_t gfn; + + kvm->arch.indirect_shadow_pages--; + gfn = sp->gfn; + slots = kvm_memslots_for_spte_role(kvm, sp->role); + slot = __gfn_to_memslot(slots, gfn); + if (sp->role.level > PG_LEVEL_4K) + return kvm_slot_page_track_remove_page(kvm, slot, gfn, + KVM_PAGE_TRACK_WRITE); + + kvm_mmu_gfn_allow_lpage(slot, gfn); +} + +void unaccount_huge_nx_page(struct kvm *kvm, struct kvm_mmu_page *sp) +{ + --kvm->stat.nx_lpage_splits; + sp->lpage_disallowed = false; + list_del(&sp->lpage_disallowed_link); +} + +static struct kvm_memory_slot * +gfn_to_memslot_dirty_bitmap(struct kvm_vcpu *vcpu, gfn_t gfn, + bool no_dirty_log) +{ + struct kvm_memory_slot *slot; + + slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn); + if (!slot || slot->flags & KVM_MEMSLOT_INVALID) + return NULL; + if (no_dirty_log && kvm_slot_dirty_track_enabled(slot)) + return NULL; + + return slot; +} + +/* + * About rmap_head encoding: + * + * If the bit zero of rmap_head->val is clear, then it points to the only spte + * in this rmap chain. Otherwise, (rmap_head->val & ~1) points to a struct + * pte_list_desc containing more mappings. + */ + +/* + * Returns the number of pointers in the rmap chain, not counting the new one. + */ +static int pte_list_add(struct kvm_mmu_memory_cache *cache, u64 *spte, + struct kvm_rmap_head *rmap_head) +{ + struct pte_list_desc *desc; + int count = 0; + + if (!rmap_head->val) { + rmap_printk("%p %llx 0->1\n", spte, *spte); + rmap_head->val = (unsigned long)spte; + } else if (!(rmap_head->val & 1)) { + rmap_printk("%p %llx 1->many\n", spte, *spte); + desc = kvm_mmu_memory_cache_alloc(cache); + desc->sptes[0] = (u64 *)rmap_head->val; + desc->sptes[1] = spte; + desc->spte_count = 2; + rmap_head->val = (unsigned long)desc | 1; + ++count; + } else { + rmap_printk("%p %llx many->many\n", spte, *spte); + desc = (struct pte_list_desc *)(rmap_head->val & ~1ul); + while (desc->spte_count == PTE_LIST_EXT) { + count += PTE_LIST_EXT; + if (!desc->more) { + desc->more = kvm_mmu_memory_cache_alloc(cache); + desc = desc->more; + desc->spte_count = 0; + break; + } + desc = desc->more; + } + count += desc->spte_count; + desc->sptes[desc->spte_count++] = spte; + } + return count; +} + +static void +pte_list_desc_remove_entry(struct kvm_rmap_head *rmap_head, + struct pte_list_desc *desc, int i, + struct pte_list_desc *prev_desc) +{ + int j = desc->spte_count - 1; + + desc->sptes[i] = desc->sptes[j]; + desc->sptes[j] = NULL; + desc->spte_count--; + if (desc->spte_count) + return; + if (!prev_desc && !desc->more) + rmap_head->val = 0; + else + if (prev_desc) + prev_desc->more = desc->more; + else + rmap_head->val = (unsigned long)desc->more | 1; + mmu_free_pte_list_desc(desc); +} + +static void pte_list_remove(u64 *spte, struct kvm_rmap_head *rmap_head) +{ + struct pte_list_desc *desc; + struct pte_list_desc *prev_desc; + int i; + + if (!rmap_head->val) { + pr_err("%s: %p 0->BUG\n", __func__, spte); + BUG(); + } else if (!(rmap_head->val & 1)) { + rmap_printk("%p 1->0\n", spte); + if ((u64 *)rmap_head->val != spte) { + pr_err("%s: %p 1->BUG\n", __func__, spte); + BUG(); + } + rmap_head->val = 0; + } else { + rmap_printk("%p many->many\n", spte); + desc = (struct pte_list_desc *)(rmap_head->val & ~1ul); + prev_desc = NULL; + while (desc) { + for (i = 0; i < desc->spte_count; ++i) { + if (desc->sptes[i] == spte) { + pte_list_desc_remove_entry(rmap_head, + desc, i, prev_desc); + return; + } + } + prev_desc = desc; + desc = desc->more; + } + pr_err("%s: %p many->many\n", __func__, spte); + BUG(); + } +} + +static void kvm_zap_one_rmap_spte(struct kvm *kvm, + struct kvm_rmap_head *rmap_head, u64 *sptep) +{ + mmu_spte_clear_track_bits(kvm, sptep); + pte_list_remove(sptep, rmap_head); +} + +/* Return true if at least one SPTE was zapped, false otherwise */ +static bool kvm_zap_all_rmap_sptes(struct kvm *kvm, + struct kvm_rmap_head *rmap_head) +{ + struct pte_list_desc *desc, *next; + int i; + + if (!rmap_head->val) + return false; + + if (!(rmap_head->val & 1)) { + mmu_spte_clear_track_bits(kvm, (u64 *)rmap_head->val); + goto out; + } + + desc = (struct pte_list_desc *)(rmap_head->val & ~1ul); + + for (; desc; desc = next) { + for (i = 0; i < desc->spte_count; i++) + mmu_spte_clear_track_bits(kvm, desc->sptes[i]); + next = desc->more; + mmu_free_pte_list_desc(desc); + } +out: + /* rmap_head is meaningless now, remember to reset it */ + rmap_head->val = 0; + return true; +} + +unsigned int pte_list_count(struct kvm_rmap_head *rmap_head) +{ + struct pte_list_desc *desc; + unsigned int count = 0; + + if (!rmap_head->val) + return 0; + else if (!(rmap_head->val & 1)) + return 1; + + desc = (struct pte_list_desc *)(rmap_head->val & ~1ul); + + while (desc) { + count += desc->spte_count; + desc = desc->more; + } + + return count; +} + +static struct kvm_rmap_head *gfn_to_rmap(gfn_t gfn, int level, + const struct kvm_memory_slot *slot) +{ + unsigned long idx; + + idx = gfn_to_index(gfn, slot->base_gfn, level); + return &slot->arch.rmap[level - PG_LEVEL_4K][idx]; +} + +static bool rmap_can_add(struct kvm_vcpu *vcpu) +{ + struct kvm_mmu_memory_cache *mc; + + mc = &vcpu->arch.mmu_pte_list_desc_cache; + return kvm_mmu_memory_cache_nr_free_objects(mc); +} + +static void rmap_remove(struct kvm *kvm, u64 *spte) +{ + struct kvm_memslots *slots; + struct kvm_memory_slot *slot; + struct kvm_mmu_page *sp; + gfn_t gfn; + struct kvm_rmap_head *rmap_head; + + sp = sptep_to_sp(spte); + gfn = kvm_mmu_page_get_gfn(sp, spte_index(spte)); + + /* + * Unlike rmap_add, rmap_remove does not run in the context of a vCPU + * so we have to determine which memslots to use based on context + * information in sp->role. + */ + slots = kvm_memslots_for_spte_role(kvm, sp->role); + + slot = __gfn_to_memslot(slots, gfn); + rmap_head = gfn_to_rmap(gfn, sp->role.level, slot); + + pte_list_remove(spte, rmap_head); +} + +/* + * Used by the following functions to iterate through the sptes linked by a + * rmap. All fields are private and not assumed to be used outside. + */ +struct rmap_iterator { + /* private fields */ + struct pte_list_desc *desc; /* holds the sptep if not NULL */ + int pos; /* index of the sptep */ +}; + +/* + * Iteration must be started by this function. This should also be used after + * removing/dropping sptes from the rmap link because in such cases the + * information in the iterator may not be valid. + * + * Returns sptep if found, NULL otherwise. + */ +static u64 *rmap_get_first(struct kvm_rmap_head *rmap_head, + struct rmap_iterator *iter) +{ + u64 *sptep; + + if (!rmap_head->val) + return NULL; + + if (!(rmap_head->val & 1)) { + iter->desc = NULL; + sptep = (u64 *)rmap_head->val; + goto out; + } + + iter->desc = (struct pte_list_desc *)(rmap_head->val & ~1ul); + iter->pos = 0; + sptep = iter->desc->sptes[iter->pos]; +out: + BUG_ON(!is_shadow_present_pte(*sptep)); + return sptep; +} + +/* + * Must be used with a valid iterator: e.g. after rmap_get_first(). + * + * Returns sptep if found, NULL otherwise. + */ +static u64 *rmap_get_next(struct rmap_iterator *iter) +{ + u64 *sptep; + + if (iter->desc) { + if (iter->pos < PTE_LIST_EXT - 1) { + ++iter->pos; + sptep = iter->desc->sptes[iter->pos]; + if (sptep) + goto out; + } + + iter->desc = iter->desc->more; + + if (iter->desc) { + iter->pos = 0; + /* desc->sptes[0] cannot be NULL */ + sptep = iter->desc->sptes[iter->pos]; + goto out; + } + } + + return NULL; +out: + BUG_ON(!is_shadow_present_pte(*sptep)); + return sptep; +} + +#define for_each_rmap_spte(_rmap_head_, _iter_, _spte_) \ + for (_spte_ = rmap_get_first(_rmap_head_, _iter_); \ + _spte_; _spte_ = rmap_get_next(_iter_)) + +static void drop_spte(struct kvm *kvm, u64 *sptep) +{ + u64 old_spte = mmu_spte_clear_track_bits(kvm, sptep); + + if (is_shadow_present_pte(old_spte)) + rmap_remove(kvm, sptep); +} + +static void drop_large_spte(struct kvm *kvm, u64 *sptep, bool flush) +{ + struct kvm_mmu_page *sp; + + sp = sptep_to_sp(sptep); + WARN_ON(sp->role.level == PG_LEVEL_4K); + + drop_spte(kvm, sptep); + + if (flush) + kvm_flush_remote_tlbs_with_address(kvm, sp->gfn, + KVM_PAGES_PER_HPAGE(sp->role.level)); +} + +/* + * Write-protect on the specified @sptep, @pt_protect indicates whether + * spte write-protection is caused by protecting shadow page table. + * + * Note: write protection is difference between dirty logging and spte + * protection: + * - for dirty logging, the spte can be set to writable at anytime if + * its dirty bitmap is properly set. + * - for spte protection, the spte can be writable only after unsync-ing + * shadow page. + * + * Return true if tlb need be flushed. + */ +static bool spte_write_protect(u64 *sptep, bool pt_protect) +{ + u64 spte = *sptep; + + if (!is_writable_pte(spte) && + !(pt_protect && is_mmu_writable_spte(spte))) + return false; + + rmap_printk("spte %p %llx\n", sptep, *sptep); + + if (pt_protect) + spte &= ~shadow_mmu_writable_mask; + spte = spte & ~PT_WRITABLE_MASK; + + return mmu_spte_update(sptep, spte); +} + +static bool rmap_write_protect(struct kvm_rmap_head *rmap_head, + bool pt_protect) +{ + u64 *sptep; + struct rmap_iterator iter; + bool flush = false; + + for_each_rmap_spte(rmap_head, &iter, sptep) + flush |= spte_write_protect(sptep, pt_protect); + + return flush; +} + +static bool spte_clear_dirty(u64 *sptep) +{ + u64 spte = *sptep; + + rmap_printk("spte %p %llx\n", sptep, *sptep); + + MMU_WARN_ON(!spte_ad_enabled(spte)); + spte &= ~shadow_dirty_mask; + return mmu_spte_update(sptep, spte); +} + +static bool spte_wrprot_for_clear_dirty(u64 *sptep) +{ + bool was_writable = test_and_clear_bit(PT_WRITABLE_SHIFT, + (unsigned long *)sptep); + if (was_writable && !spte_ad_enabled(*sptep)) + kvm_set_pfn_dirty(spte_to_pfn(*sptep)); + + return was_writable; +} + +/* + * Gets the GFN ready for another round of dirty logging by clearing the + * - D bit on ad-enabled SPTEs, and + * - W bit on ad-disabled SPTEs. + * Returns true iff any D or W bits were cleared. + */ +static bool __rmap_clear_dirty(struct kvm *kvm, struct kvm_rmap_head *rmap_head, + const struct kvm_memory_slot *slot) +{ + u64 *sptep; + struct rmap_iterator iter; + bool flush = false; + + for_each_rmap_spte(rmap_head, &iter, sptep) + if (spte_ad_need_write_protect(*sptep)) + flush |= spte_wrprot_for_clear_dirty(sptep); + else + flush |= spte_clear_dirty(sptep); + + return flush; +} + +/** + * kvm_mmu_write_protect_pt_masked - write protect selected PT level pages + * @kvm: kvm instance + * @slot: slot to protect + * @gfn_offset: start of the BITS_PER_LONG pages we care about + * @mask: indicates which pages we should protect + * + * Used when we do not need to care about huge page mappings. + */ +static void kvm_mmu_write_protect_pt_masked(struct kvm *kvm, + struct kvm_memory_slot *slot, + gfn_t gfn_offset, unsigned long mask) +{ + struct kvm_rmap_head *rmap_head; + + if (is_tdp_mmu_enabled(kvm)) + kvm_tdp_mmu_clear_dirty_pt_masked(kvm, slot, + slot->base_gfn + gfn_offset, mask, true); + + if (!kvm_memslots_have_rmaps(kvm)) + return; + + while (mask) { + rmap_head = gfn_to_rmap(slot->base_gfn + gfn_offset + __ffs(mask), + PG_LEVEL_4K, slot); + rmap_write_protect(rmap_head, false); + + /* clear the first set bit */ + mask &= mask - 1; + } +} + +/** + * kvm_mmu_clear_dirty_pt_masked - clear MMU D-bit for PT level pages, or write + * protect the page if the D-bit isn't supported. + * @kvm: kvm instance + * @slot: slot to clear D-bit + * @gfn_offset: start of the BITS_PER_LONG pages we care about + * @mask: indicates which pages we should clear D-bit + * + * Used for PML to re-log the dirty GPAs after userspace querying dirty_bitmap. + */ +static void kvm_mmu_clear_dirty_pt_masked(struct kvm *kvm, + struct kvm_memory_slot *slot, + gfn_t gfn_offset, unsigned long mask) +{ + struct kvm_rmap_head *rmap_head; + + if (is_tdp_mmu_enabled(kvm)) + kvm_tdp_mmu_clear_dirty_pt_masked(kvm, slot, + slot->base_gfn + gfn_offset, mask, false); + + if (!kvm_memslots_have_rmaps(kvm)) + return; + + while (mask) { + rmap_head = gfn_to_rmap(slot->base_gfn + gfn_offset + __ffs(mask), + PG_LEVEL_4K, slot); + __rmap_clear_dirty(kvm, rmap_head, slot); + + /* clear the first set bit */ + mask &= mask - 1; + } +} + +/** + * kvm_arch_mmu_enable_log_dirty_pt_masked - enable dirty logging for selected + * PT level pages. + * + * It calls kvm_mmu_write_protect_pt_masked to write protect selected pages to + * enable dirty logging for them. + * + * We need to care about huge page mappings: e.g. during dirty logging we may + * have such mappings. + */ +void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm, + struct kvm_memory_slot *slot, + gfn_t gfn_offset, unsigned long mask) +{ + /* + * Huge pages are NOT write protected when we start dirty logging in + * initially-all-set mode; must write protect them here so that they + * are split to 4K on the first write. + * + * The gfn_offset is guaranteed to be aligned to 64, but the base_gfn + * of memslot has no such restriction, so the range can cross two large + * pages. + */ + if (kvm_dirty_log_manual_protect_and_init_set(kvm)) { + gfn_t start = slot->base_gfn + gfn_offset + __ffs(mask); + gfn_t end = slot->base_gfn + gfn_offset + __fls(mask); + + if (READ_ONCE(eager_page_split)) + kvm_mmu_try_split_huge_pages(kvm, slot, start, end, PG_LEVEL_4K); + + kvm_mmu_slot_gfn_write_protect(kvm, slot, start, PG_LEVEL_2M); + + /* Cross two large pages? */ + if (ALIGN(start << PAGE_SHIFT, PMD_SIZE) != + ALIGN(end << PAGE_SHIFT, PMD_SIZE)) + kvm_mmu_slot_gfn_write_protect(kvm, slot, end, + PG_LEVEL_2M); + } + + /* Now handle 4K PTEs. */ + if (kvm_x86_ops.cpu_dirty_log_size) + kvm_mmu_clear_dirty_pt_masked(kvm, slot, gfn_offset, mask); + else + kvm_mmu_write_protect_pt_masked(kvm, slot, gfn_offset, mask); +} + +int kvm_cpu_dirty_log_size(void) +{ + return kvm_x86_ops.cpu_dirty_log_size; +} + +bool kvm_mmu_slot_gfn_write_protect(struct kvm *kvm, + struct kvm_memory_slot *slot, u64 gfn, + int min_level) +{ + struct kvm_rmap_head *rmap_head; + int i; + bool write_protected = false; + + if (kvm_memslots_have_rmaps(kvm)) { + for (i = min_level; i <= KVM_MAX_HUGEPAGE_LEVEL; ++i) { + rmap_head = gfn_to_rmap(gfn, i, slot); + write_protected |= rmap_write_protect(rmap_head, true); + } + } + + if (is_tdp_mmu_enabled(kvm)) + write_protected |= + kvm_tdp_mmu_write_protect_gfn(kvm, slot, gfn, min_level); + + return write_protected; +} + +static bool kvm_vcpu_write_protect_gfn(struct kvm_vcpu *vcpu, u64 gfn) +{ + struct kvm_memory_slot *slot; + + slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn); + return kvm_mmu_slot_gfn_write_protect(vcpu->kvm, slot, gfn, PG_LEVEL_4K); +} + +static bool __kvm_zap_rmap(struct kvm *kvm, struct kvm_rmap_head *rmap_head, + const struct kvm_memory_slot *slot) +{ + return kvm_zap_all_rmap_sptes(kvm, rmap_head); +} + +static bool kvm_zap_rmap(struct kvm *kvm, struct kvm_rmap_head *rmap_head, + struct kvm_memory_slot *slot, gfn_t gfn, int level, + pte_t unused) +{ + return __kvm_zap_rmap(kvm, rmap_head, slot); +} + +static bool kvm_set_pte_rmap(struct kvm *kvm, struct kvm_rmap_head *rmap_head, + struct kvm_memory_slot *slot, gfn_t gfn, int level, + pte_t pte) +{ + u64 *sptep; + struct rmap_iterator iter; + bool need_flush = false; + u64 new_spte; + kvm_pfn_t new_pfn; + + WARN_ON(pte_huge(pte)); + new_pfn = pte_pfn(pte); + +restart: + for_each_rmap_spte(rmap_head, &iter, sptep) { + rmap_printk("spte %p %llx gfn %llx (%d)\n", + sptep, *sptep, gfn, level); + + need_flush = true; + + if (pte_write(pte)) { + kvm_zap_one_rmap_spte(kvm, rmap_head, sptep); + goto restart; + } else { + new_spte = kvm_mmu_changed_pte_notifier_make_spte( + *sptep, new_pfn); + + mmu_spte_clear_track_bits(kvm, sptep); + mmu_spte_set(sptep, new_spte); + } + } + + if (need_flush && kvm_available_flush_tlb_with_range()) { + kvm_flush_remote_tlbs_with_address(kvm, gfn, 1); + return false; + } + + return need_flush; +} + +struct slot_rmap_walk_iterator { + /* input fields. */ + const struct kvm_memory_slot *slot; + gfn_t start_gfn; + gfn_t end_gfn; + int start_level; + int end_level; + + /* output fields. */ + gfn_t gfn; + struct kvm_rmap_head *rmap; + int level; + + /* private field. */ + struct kvm_rmap_head *end_rmap; +}; + +static void +rmap_walk_init_level(struct slot_rmap_walk_iterator *iterator, int level) +{ + iterator->level = level; + iterator->gfn = iterator->start_gfn; + iterator->rmap = gfn_to_rmap(iterator->gfn, level, iterator->slot); + iterator->end_rmap = gfn_to_rmap(iterator->end_gfn, level, iterator->slot); +} + +static void +slot_rmap_walk_init(struct slot_rmap_walk_iterator *iterator, + const struct kvm_memory_slot *slot, int start_level, + int end_level, gfn_t start_gfn, gfn_t end_gfn) +{ + iterator->slot = slot; + iterator->start_level = start_level; + iterator->end_level = end_level; + iterator->start_gfn = start_gfn; + iterator->end_gfn = end_gfn; + + rmap_walk_init_level(iterator, iterator->start_level); +} + +static bool slot_rmap_walk_okay(struct slot_rmap_walk_iterator *iterator) +{ + return !!iterator->rmap; +} + +static void slot_rmap_walk_next(struct slot_rmap_walk_iterator *iterator) +{ + while (++iterator->rmap <= iterator->end_rmap) { + iterator->gfn += (1UL << KVM_HPAGE_GFN_SHIFT(iterator->level)); + + if (iterator->rmap->val) + return; + } + + if (++iterator->level > iterator->end_level) { + iterator->rmap = NULL; + return; + } + + rmap_walk_init_level(iterator, iterator->level); +} + +#define for_each_slot_rmap_range(_slot_, _start_level_, _end_level_, \ + _start_gfn, _end_gfn, _iter_) \ + for (slot_rmap_walk_init(_iter_, _slot_, _start_level_, \ + _end_level_, _start_gfn, _end_gfn); \ + slot_rmap_walk_okay(_iter_); \ + slot_rmap_walk_next(_iter_)) + +typedef bool (*rmap_handler_t)(struct kvm *kvm, struct kvm_rmap_head *rmap_head, + struct kvm_memory_slot *slot, gfn_t gfn, + int level, pte_t pte); + +static __always_inline bool kvm_handle_gfn_range(struct kvm *kvm, + struct kvm_gfn_range *range, + rmap_handler_t handler) +{ + struct slot_rmap_walk_iterator iterator; + bool ret = false; + + for_each_slot_rmap_range(range->slot, PG_LEVEL_4K, KVM_MAX_HUGEPAGE_LEVEL, + range->start, range->end - 1, &iterator) + ret |= handler(kvm, iterator.rmap, range->slot, iterator.gfn, + iterator.level, range->pte); + + return ret; +} + +bool kvm_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range) +{ + bool flush = false; + + if (kvm_memslots_have_rmaps(kvm)) + flush = kvm_handle_gfn_range(kvm, range, kvm_zap_rmap); + + if (is_tdp_mmu_enabled(kvm)) + flush = kvm_tdp_mmu_unmap_gfn_range(kvm, range, flush); + + return flush; +} + +bool kvm_set_spte_gfn(struct kvm *kvm, struct kvm_gfn_range *range) +{ + bool flush = false; + + if (kvm_memslots_have_rmaps(kvm)) + flush = kvm_handle_gfn_range(kvm, range, kvm_set_pte_rmap); + + if (is_tdp_mmu_enabled(kvm)) + flush |= kvm_tdp_mmu_set_spte_gfn(kvm, range); + + return flush; +} + +static bool kvm_age_rmap(struct kvm *kvm, struct kvm_rmap_head *rmap_head, + struct kvm_memory_slot *slot, gfn_t gfn, int level, + pte_t unused) +{ + u64 *sptep; + struct rmap_iterator iter; + int young = 0; + + for_each_rmap_spte(rmap_head, &iter, sptep) + young |= mmu_spte_age(sptep); + + return young; +} + +static bool kvm_test_age_rmap(struct kvm *kvm, struct kvm_rmap_head *rmap_head, + struct kvm_memory_slot *slot, gfn_t gfn, + int level, pte_t unused) +{ + u64 *sptep; + struct rmap_iterator iter; + + for_each_rmap_spte(rmap_head, &iter, sptep) + if (is_accessed_spte(*sptep)) + return true; + return false; +} + +#define RMAP_RECYCLE_THRESHOLD 1000 + +static void __rmap_add(struct kvm *kvm, + struct kvm_mmu_memory_cache *cache, + const struct kvm_memory_slot *slot, + u64 *spte, gfn_t gfn, unsigned int access) +{ + struct kvm_mmu_page *sp; + struct kvm_rmap_head *rmap_head; + int rmap_count; + + sp = sptep_to_sp(spte); + kvm_mmu_page_set_translation(sp, spte_index(spte), gfn, access); + kvm_update_page_stats(kvm, sp->role.level, 1); + + rmap_head = gfn_to_rmap(gfn, sp->role.level, slot); + rmap_count = pte_list_add(cache, spte, rmap_head); + + if (rmap_count > kvm->stat.max_mmu_rmap_size) + kvm->stat.max_mmu_rmap_size = rmap_count; + if (rmap_count > RMAP_RECYCLE_THRESHOLD) { + kvm_zap_all_rmap_sptes(kvm, rmap_head); + kvm_flush_remote_tlbs_with_address( + kvm, sp->gfn, KVM_PAGES_PER_HPAGE(sp->role.level)); + } +} + +static void rmap_add(struct kvm_vcpu *vcpu, const struct kvm_memory_slot *slot, + u64 *spte, gfn_t gfn, unsigned int access) +{ + struct kvm_mmu_memory_cache *cache = &vcpu->arch.mmu_pte_list_desc_cache; + + __rmap_add(vcpu->kvm, cache, slot, spte, gfn, access); +} + +bool kvm_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range) +{ + bool young = false; + + if (kvm_memslots_have_rmaps(kvm)) + young = kvm_handle_gfn_range(kvm, range, kvm_age_rmap); + + if (is_tdp_mmu_enabled(kvm)) + young |= kvm_tdp_mmu_age_gfn_range(kvm, range); + + return young; +} + +bool kvm_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range) +{ + bool young = false; + + if (kvm_memslots_have_rmaps(kvm)) + young = kvm_handle_gfn_range(kvm, range, kvm_test_age_rmap); + + if (is_tdp_mmu_enabled(kvm)) + young |= kvm_tdp_mmu_test_age_gfn(kvm, range); + + return young; +} + +#ifdef MMU_DEBUG +static int is_empty_shadow_page(u64 *spt) +{ + u64 *pos; + u64 *end; + + for (pos = spt, end = pos + PAGE_SIZE / sizeof(u64); pos != end; pos++) + if (is_shadow_present_pte(*pos)) { + printk(KERN_ERR "%s: %p %llx\n", __func__, + pos, *pos); + return 0; + } + return 1; +} +#endif + +/* + * This value is the sum of all of the kvm instances's + * kvm->arch.n_used_mmu_pages values. We need a global, + * aggregate version in order to make the slab shrinker + * faster + */ +static inline void kvm_mod_used_mmu_pages(struct kvm *kvm, long nr) +{ + kvm->arch.n_used_mmu_pages += nr; + percpu_counter_add(&kvm_total_used_mmu_pages, nr); +} + +static void kvm_account_mmu_page(struct kvm *kvm, struct kvm_mmu_page *sp) +{ + kvm_mod_used_mmu_pages(kvm, +1); + kvm_account_pgtable_pages((void *)sp->spt, +1); +} + +static void kvm_unaccount_mmu_page(struct kvm *kvm, struct kvm_mmu_page *sp) +{ + kvm_mod_used_mmu_pages(kvm, -1); + kvm_account_pgtable_pages((void *)sp->spt, -1); +} + +static void kvm_mmu_free_shadow_page(struct kvm_mmu_page *sp) +{ + MMU_WARN_ON(!is_empty_shadow_page(sp->spt)); + hlist_del(&sp->hash_link); + list_del(&sp->link); + free_page((unsigned long)sp->spt); + if (!sp->role.direct) + free_page((unsigned long)sp->shadowed_translation); + kmem_cache_free(mmu_page_header_cache, sp); +} + +static unsigned kvm_page_table_hashfn(gfn_t gfn) +{ + return hash_64(gfn, KVM_MMU_HASH_SHIFT); +} + +static void mmu_page_add_parent_pte(struct kvm_mmu_memory_cache *cache, + struct kvm_mmu_page *sp, u64 *parent_pte) +{ + if (!parent_pte) + return; + + pte_list_add(cache, parent_pte, &sp->parent_ptes); +} + +static void mmu_page_remove_parent_pte(struct kvm_mmu_page *sp, + u64 *parent_pte) +{ + pte_list_remove(parent_pte, &sp->parent_ptes); +} + +static void drop_parent_pte(struct kvm_mmu_page *sp, + u64 *parent_pte) +{ + mmu_page_remove_parent_pte(sp, parent_pte); + mmu_spte_clear_no_track(parent_pte); +} + +static void mark_unsync(u64 *spte); +static void kvm_mmu_mark_parents_unsync(struct kvm_mmu_page *sp) +{ + u64 *sptep; + struct rmap_iterator iter; + + for_each_rmap_spte(&sp->parent_ptes, &iter, sptep) { + mark_unsync(sptep); + } +} + +static void mark_unsync(u64 *spte) +{ + struct kvm_mmu_page *sp; + + sp = sptep_to_sp(spte); + if (__test_and_set_bit(spte_index(spte), sp->unsync_child_bitmap)) + return; + if (sp->unsync_children++) + return; + kvm_mmu_mark_parents_unsync(sp); +} + +static int nonpaging_sync_page(struct kvm_vcpu *vcpu, + struct kvm_mmu_page *sp) +{ + return -1; +} + +#define KVM_PAGE_ARRAY_NR 16 + +struct kvm_mmu_pages { + struct mmu_page_and_offset { + struct kvm_mmu_page *sp; + unsigned int idx; + } page[KVM_PAGE_ARRAY_NR]; + unsigned int nr; +}; + +static int mmu_pages_add(struct kvm_mmu_pages *pvec, struct kvm_mmu_page *sp, + int idx) +{ + int i; + + if (sp->unsync) + for (i=0; i < pvec->nr; i++) + if (pvec->page[i].sp == sp) + return 0; + + pvec->page[pvec->nr].sp = sp; + pvec->page[pvec->nr].idx = idx; + pvec->nr++; + return (pvec->nr == KVM_PAGE_ARRAY_NR); +} + +static inline void clear_unsync_child_bit(struct kvm_mmu_page *sp, int idx) +{ + --sp->unsync_children; + WARN_ON((int)sp->unsync_children < 0); + __clear_bit(idx, sp->unsync_child_bitmap); +} + +static int __mmu_unsync_walk(struct kvm_mmu_page *sp, + struct kvm_mmu_pages *pvec) +{ + int i, ret, nr_unsync_leaf = 0; + + for_each_set_bit(i, sp->unsync_child_bitmap, 512) { + struct kvm_mmu_page *child; + u64 ent = sp->spt[i]; + + if (!is_shadow_present_pte(ent) || is_large_pte(ent)) { + clear_unsync_child_bit(sp, i); + continue; + } + + child = to_shadow_page(ent & SPTE_BASE_ADDR_MASK); + + if (child->unsync_children) { + if (mmu_pages_add(pvec, child, i)) + return -ENOSPC; + + ret = __mmu_unsync_walk(child, pvec); + if (!ret) { + clear_unsync_child_bit(sp, i); + continue; + } else if (ret > 0) { + nr_unsync_leaf += ret; + } else + return ret; + } else if (child->unsync) { + nr_unsync_leaf++; + if (mmu_pages_add(pvec, child, i)) + return -ENOSPC; + } else + clear_unsync_child_bit(sp, i); + } + + return nr_unsync_leaf; +} + +#define INVALID_INDEX (-1) + +static int mmu_unsync_walk(struct kvm_mmu_page *sp, + struct kvm_mmu_pages *pvec) +{ + pvec->nr = 0; + if (!sp->unsync_children) + return 0; + + mmu_pages_add(pvec, sp, INVALID_INDEX); + return __mmu_unsync_walk(sp, pvec); +} + +static void kvm_unlink_unsync_page(struct kvm *kvm, struct kvm_mmu_page *sp) +{ + WARN_ON(!sp->unsync); + trace_kvm_mmu_sync_page(sp); + sp->unsync = 0; + --kvm->stat.mmu_unsync; +} + +static bool kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp, + struct list_head *invalid_list); +static void kvm_mmu_commit_zap_page(struct kvm *kvm, + struct list_head *invalid_list); + +static bool sp_has_gptes(struct kvm_mmu_page *sp) +{ + if (sp->role.direct) + return false; + + if (sp->role.passthrough) + return false; + + return true; +} + +#define for_each_valid_sp(_kvm, _sp, _list) \ + hlist_for_each_entry(_sp, _list, hash_link) \ + if (is_obsolete_sp((_kvm), (_sp))) { \ + } else + +#define for_each_gfn_valid_sp_with_gptes(_kvm, _sp, _gfn) \ + for_each_valid_sp(_kvm, _sp, \ + &(_kvm)->arch.mmu_page_hash[kvm_page_table_hashfn(_gfn)]) \ + if ((_sp)->gfn != (_gfn) || !sp_has_gptes(_sp)) {} else + +static int kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, + struct list_head *invalid_list) +{ + int ret = vcpu->arch.mmu->sync_page(vcpu, sp); + + if (ret < 0) + kvm_mmu_prepare_zap_page(vcpu->kvm, sp, invalid_list); + return ret; +} + +static bool kvm_mmu_remote_flush_or_zap(struct kvm *kvm, + struct list_head *invalid_list, + bool remote_flush) +{ + if (!remote_flush && list_empty(invalid_list)) + return false; + + if (!list_empty(invalid_list)) + kvm_mmu_commit_zap_page(kvm, invalid_list); + else + kvm_flush_remote_tlbs(kvm); + return true; +} + +static bool is_obsolete_sp(struct kvm *kvm, struct kvm_mmu_page *sp) +{ + if (sp->role.invalid) + return true; + + /* TDP MMU pages due not use the MMU generation. */ + return !sp->tdp_mmu_page && + unlikely(sp->mmu_valid_gen != kvm->arch.mmu_valid_gen); +} + +struct mmu_page_path { + struct kvm_mmu_page *parent[PT64_ROOT_MAX_LEVEL]; + unsigned int idx[PT64_ROOT_MAX_LEVEL]; +}; + +#define for_each_sp(pvec, sp, parents, i) \ + for (i = mmu_pages_first(&pvec, &parents); \ + i < pvec.nr && ({ sp = pvec.page[i].sp; 1;}); \ + i = mmu_pages_next(&pvec, &parents, i)) + +static int mmu_pages_next(struct kvm_mmu_pages *pvec, + struct mmu_page_path *parents, + int i) +{ + int n; + + for (n = i+1; n < pvec->nr; n++) { + struct kvm_mmu_page *sp = pvec->page[n].sp; + unsigned idx = pvec->page[n].idx; + int level = sp->role.level; + + parents->idx[level-1] = idx; + if (level == PG_LEVEL_4K) + break; + + parents->parent[level-2] = sp; + } + + return n; +} + +static int mmu_pages_first(struct kvm_mmu_pages *pvec, + struct mmu_page_path *parents) +{ + struct kvm_mmu_page *sp; + int level; + + if (pvec->nr == 0) + return 0; + + WARN_ON(pvec->page[0].idx != INVALID_INDEX); + + sp = pvec->page[0].sp; + level = sp->role.level; + WARN_ON(level == PG_LEVEL_4K); + + parents->parent[level-2] = sp; + + /* Also set up a sentinel. Further entries in pvec are all + * children of sp, so this element is never overwritten. + */ + parents->parent[level-1] = NULL; + return mmu_pages_next(pvec, parents, 0); +} + +static void mmu_pages_clear_parents(struct mmu_page_path *parents) +{ + struct kvm_mmu_page *sp; + unsigned int level = 0; + + do { + unsigned int idx = parents->idx[level]; + sp = parents->parent[level]; + if (!sp) + return; + + WARN_ON(idx == INVALID_INDEX); + clear_unsync_child_bit(sp, idx); + level++; + } while (!sp->unsync_children); +} + +static int mmu_sync_children(struct kvm_vcpu *vcpu, + struct kvm_mmu_page *parent, bool can_yield) +{ + int i; + struct kvm_mmu_page *sp; + struct mmu_page_path parents; + struct kvm_mmu_pages pages; + LIST_HEAD(invalid_list); + bool flush = false; + + while (mmu_unsync_walk(parent, &pages)) { + bool protected = false; + + for_each_sp(pages, sp, parents, i) + protected |= kvm_vcpu_write_protect_gfn(vcpu, sp->gfn); + + if (protected) { + kvm_mmu_remote_flush_or_zap(vcpu->kvm, &invalid_list, true); + flush = false; + } + + for_each_sp(pages, sp, parents, i) { + kvm_unlink_unsync_page(vcpu->kvm, sp); + flush |= kvm_sync_page(vcpu, sp, &invalid_list) > 0; + mmu_pages_clear_parents(&parents); + } + if (need_resched() || rwlock_needbreak(&vcpu->kvm->mmu_lock)) { + kvm_mmu_remote_flush_or_zap(vcpu->kvm, &invalid_list, flush); + if (!can_yield) { + kvm_make_request(KVM_REQ_MMU_SYNC, vcpu); + return -EINTR; + } + + cond_resched_rwlock_write(&vcpu->kvm->mmu_lock); + flush = false; + } + } + + kvm_mmu_remote_flush_or_zap(vcpu->kvm, &invalid_list, flush); + return 0; +} + +static void __clear_sp_write_flooding_count(struct kvm_mmu_page *sp) +{ + atomic_set(&sp->write_flooding_count, 0); +} + +static void clear_sp_write_flooding_count(u64 *spte) +{ + __clear_sp_write_flooding_count(sptep_to_sp(spte)); +} + +/* + * The vCPU is required when finding indirect shadow pages; the shadow + * page may already exist and syncing it needs the vCPU pointer in + * order to read guest page tables. Direct shadow pages are never + * unsync, thus @vcpu can be NULL if @role.direct is true. + */ +static struct kvm_mmu_page *kvm_mmu_find_shadow_page(struct kvm *kvm, + struct kvm_vcpu *vcpu, + gfn_t gfn, + struct hlist_head *sp_list, + union kvm_mmu_page_role role) +{ + struct kvm_mmu_page *sp; + int ret; + int collisions = 0; + LIST_HEAD(invalid_list); + + for_each_valid_sp(kvm, sp, sp_list) { + if (sp->gfn != gfn) { + collisions++; + continue; + } + + if (sp->role.word != role.word) { + /* + * If the guest is creating an upper-level page, zap + * unsync pages for the same gfn. While it's possible + * the guest is using recursive page tables, in all + * likelihood the guest has stopped using the unsync + * page and is installing a completely unrelated page. + * Unsync pages must not be left as is, because the new + * upper-level page will be write-protected. + */ + if (role.level > PG_LEVEL_4K && sp->unsync) + kvm_mmu_prepare_zap_page(kvm, sp, + &invalid_list); + continue; + } + + /* unsync and write-flooding only apply to indirect SPs. */ + if (sp->role.direct) + goto out; + + if (sp->unsync) { + if (KVM_BUG_ON(!vcpu, kvm)) + break; + + /* + * The page is good, but is stale. kvm_sync_page does + * get the latest guest state, but (unlike mmu_unsync_children) + * it doesn't write-protect the page or mark it synchronized! + * This way the validity of the mapping is ensured, but the + * overhead of write protection is not incurred until the + * guest invalidates the TLB mapping. This allows multiple + * SPs for a single gfn to be unsync. + * + * If the sync fails, the page is zapped. If so, break + * in order to rebuild it. + */ + ret = kvm_sync_page(vcpu, sp, &invalid_list); + if (ret < 0) + break; + + WARN_ON(!list_empty(&invalid_list)); + if (ret > 0) + kvm_flush_remote_tlbs(kvm); + } + + __clear_sp_write_flooding_count(sp); + + goto out; + } + + sp = NULL; + ++kvm->stat.mmu_cache_miss; + +out: + kvm_mmu_commit_zap_page(kvm, &invalid_list); + + if (collisions > kvm->stat.max_mmu_page_hash_collisions) + kvm->stat.max_mmu_page_hash_collisions = collisions; + return sp; +} + +/* Caches used when allocating a new shadow page. */ +struct shadow_page_caches { + struct kvm_mmu_memory_cache *page_header_cache; + struct kvm_mmu_memory_cache *shadow_page_cache; + struct kvm_mmu_memory_cache *shadowed_info_cache; +}; + +static struct kvm_mmu_page *kvm_mmu_alloc_shadow_page(struct kvm *kvm, + struct shadow_page_caches *caches, + gfn_t gfn, + struct hlist_head *sp_list, + union kvm_mmu_page_role role) +{ + struct kvm_mmu_page *sp; + + sp = kvm_mmu_memory_cache_alloc(caches->page_header_cache); + sp->spt = kvm_mmu_memory_cache_alloc(caches->shadow_page_cache); + if (!role.direct) + sp->shadowed_translation = kvm_mmu_memory_cache_alloc(caches->shadowed_info_cache); + + set_page_private(virt_to_page(sp->spt), (unsigned long)sp); + + /* + * active_mmu_pages must be a FIFO list, as kvm_zap_obsolete_pages() + * depends on valid pages being added to the head of the list. See + * comments in kvm_zap_obsolete_pages(). + */ + sp->mmu_valid_gen = kvm->arch.mmu_valid_gen; + list_add(&sp->link, &kvm->arch.active_mmu_pages); + kvm_account_mmu_page(kvm, sp); + + sp->gfn = gfn; + sp->role = role; + hlist_add_head(&sp->hash_link, sp_list); + if (sp_has_gptes(sp)) + account_shadowed(kvm, sp); + + return sp; +} + +/* Note, @vcpu may be NULL if @role.direct is true; see kvm_mmu_find_shadow_page. */ +static struct kvm_mmu_page *__kvm_mmu_get_shadow_page(struct kvm *kvm, + struct kvm_vcpu *vcpu, + struct shadow_page_caches *caches, + gfn_t gfn, + union kvm_mmu_page_role role) +{ + struct hlist_head *sp_list; + struct kvm_mmu_page *sp; + bool created = false; + + sp_list = &kvm->arch.mmu_page_hash[kvm_page_table_hashfn(gfn)]; + + sp = kvm_mmu_find_shadow_page(kvm, vcpu, gfn, sp_list, role); + if (!sp) { + created = true; + sp = kvm_mmu_alloc_shadow_page(kvm, caches, gfn, sp_list, role); + } + + trace_kvm_mmu_get_page(sp, created); + return sp; +} + +static struct kvm_mmu_page *kvm_mmu_get_shadow_page(struct kvm_vcpu *vcpu, + gfn_t gfn, + union kvm_mmu_page_role role) +{ + struct shadow_page_caches caches = { + .page_header_cache = &vcpu->arch.mmu_page_header_cache, + .shadow_page_cache = &vcpu->arch.mmu_shadow_page_cache, + .shadowed_info_cache = &vcpu->arch.mmu_shadowed_info_cache, + }; + + return __kvm_mmu_get_shadow_page(vcpu->kvm, vcpu, &caches, gfn, role); +} + +static union kvm_mmu_page_role kvm_mmu_child_role(u64 *sptep, bool direct, + unsigned int access) +{ + struct kvm_mmu_page *parent_sp = sptep_to_sp(sptep); + union kvm_mmu_page_role role; + + role = parent_sp->role; + role.level--; + role.access = access; + role.direct = direct; + role.passthrough = 0; + + /* + * If the guest has 4-byte PTEs then that means it's using 32-bit, + * 2-level, non-PAE paging. KVM shadows such guests with PAE paging + * (i.e. 8-byte PTEs). The difference in PTE size means that KVM must + * shadow each guest page table with multiple shadow page tables, which + * requires extra bookkeeping in the role. + * + * Specifically, to shadow the guest's page directory (which covers a + * 4GiB address space), KVM uses 4 PAE page directories, each mapping + * 1GiB of the address space. @role.quadrant encodes which quarter of + * the address space each maps. + * + * To shadow the guest's page tables (which each map a 4MiB region), KVM + * uses 2 PAE page tables, each mapping a 2MiB region. For these, + * @role.quadrant encodes which half of the region they map. + * + * Concretely, a 4-byte PDE consumes bits 31:22, while an 8-byte PDE + * consumes bits 29:21. To consume bits 31:30, KVM's uses 4 shadow + * PDPTEs; those 4 PAE page directories are pre-allocated and their + * quadrant is assigned in mmu_alloc_root(). A 4-byte PTE consumes + * bits 21:12, while an 8-byte PTE consumes bits 20:12. To consume + * bit 21 in the PTE (the child here), KVM propagates that bit to the + * quadrant, i.e. sets quadrant to '0' or '1'. The parent 8-byte PDE + * covers bit 21 (see above), thus the quadrant is calculated from the + * _least_ significant bit of the PDE index. + */ + if (role.has_4_byte_gpte) { + WARN_ON_ONCE(role.level != PG_LEVEL_4K); + role.quadrant = spte_index(sptep) & 1; + } + + return role; +} + +static struct kvm_mmu_page *kvm_mmu_get_child_sp(struct kvm_vcpu *vcpu, + u64 *sptep, gfn_t gfn, + bool direct, unsigned int access) +{ + union kvm_mmu_page_role role; + + if (is_shadow_present_pte(*sptep) && !is_large_pte(*sptep)) + return ERR_PTR(-EEXIST); + + role = kvm_mmu_child_role(sptep, direct, access); + return kvm_mmu_get_shadow_page(vcpu, gfn, role); +} + +static void shadow_walk_init_using_root(struct kvm_shadow_walk_iterator *iterator, + struct kvm_vcpu *vcpu, hpa_t root, + u64 addr) +{ + iterator->addr = addr; + iterator->shadow_addr = root; + iterator->level = vcpu->arch.mmu->root_role.level; + + if (iterator->level >= PT64_ROOT_4LEVEL && + vcpu->arch.mmu->cpu_role.base.level < PT64_ROOT_4LEVEL && + !vcpu->arch.mmu->root_role.direct) + iterator->level = PT32E_ROOT_LEVEL; + + if (iterator->level == PT32E_ROOT_LEVEL) { + /* + * prev_root is currently only used for 64-bit hosts. So only + * the active root_hpa is valid here. + */ + BUG_ON(root != vcpu->arch.mmu->root.hpa); + + iterator->shadow_addr + = vcpu->arch.mmu->pae_root[(addr >> 30) & 3]; + iterator->shadow_addr &= SPTE_BASE_ADDR_MASK; + --iterator->level; + if (!iterator->shadow_addr) + iterator->level = 0; + } +} + +static void shadow_walk_init(struct kvm_shadow_walk_iterator *iterator, + struct kvm_vcpu *vcpu, u64 addr) +{ + shadow_walk_init_using_root(iterator, vcpu, vcpu->arch.mmu->root.hpa, + addr); +} + +static bool shadow_walk_okay(struct kvm_shadow_walk_iterator *iterator) +{ + if (iterator->level < PG_LEVEL_4K) + return false; + + iterator->index = SPTE_INDEX(iterator->addr, iterator->level); + iterator->sptep = ((u64 *)__va(iterator->shadow_addr)) + iterator->index; + return true; +} + +static void __shadow_walk_next(struct kvm_shadow_walk_iterator *iterator, + u64 spte) +{ + if (!is_shadow_present_pte(spte) || is_last_spte(spte, iterator->level)) { + iterator->level = 0; + return; + } + + iterator->shadow_addr = spte & SPTE_BASE_ADDR_MASK; + --iterator->level; +} + +static void shadow_walk_next(struct kvm_shadow_walk_iterator *iterator) +{ + __shadow_walk_next(iterator, *iterator->sptep); +} + +static void __link_shadow_page(struct kvm *kvm, + struct kvm_mmu_memory_cache *cache, u64 *sptep, + struct kvm_mmu_page *sp, bool flush) +{ + u64 spte; + + BUILD_BUG_ON(VMX_EPT_WRITABLE_MASK != PT_WRITABLE_MASK); + + /* + * If an SPTE is present already, it must be a leaf and therefore + * a large one. Drop it, and flush the TLB if needed, before + * installing sp. + */ + if (is_shadow_present_pte(*sptep)) + drop_large_spte(kvm, sptep, flush); + + spte = make_nonleaf_spte(sp->spt, sp_ad_disabled(sp)); + + mmu_spte_set(sptep, spte); + + mmu_page_add_parent_pte(cache, sp, sptep); + + if (sp->unsync_children || sp->unsync) + mark_unsync(sptep); +} + +static void link_shadow_page(struct kvm_vcpu *vcpu, u64 *sptep, + struct kvm_mmu_page *sp) +{ + __link_shadow_page(vcpu->kvm, &vcpu->arch.mmu_pte_list_desc_cache, sptep, sp, true); +} + +static void validate_direct_spte(struct kvm_vcpu *vcpu, u64 *sptep, + unsigned direct_access) +{ + if (is_shadow_present_pte(*sptep) && !is_large_pte(*sptep)) { + struct kvm_mmu_page *child; + + /* + * For the direct sp, if the guest pte's dirty bit + * changed form clean to dirty, it will corrupt the + * sp's access: allow writable in the read-only sp, + * so we should update the spte at this point to get + * a new sp with the correct access. + */ + child = to_shadow_page(*sptep & SPTE_BASE_ADDR_MASK); + if (child->role.access == direct_access) + return; + + drop_parent_pte(child, sptep); + kvm_flush_remote_tlbs_with_address(vcpu->kvm, child->gfn, 1); + } +} + +/* Returns the number of zapped non-leaf child shadow pages. */ +static int mmu_page_zap_pte(struct kvm *kvm, struct kvm_mmu_page *sp, + u64 *spte, struct list_head *invalid_list) +{ + u64 pte; + struct kvm_mmu_page *child; + + pte = *spte; + if (is_shadow_present_pte(pte)) { + if (is_last_spte(pte, sp->role.level)) { + drop_spte(kvm, spte); + } else { + child = to_shadow_page(pte & SPTE_BASE_ADDR_MASK); + drop_parent_pte(child, spte); + + /* + * Recursively zap nested TDP SPs, parentless SPs are + * unlikely to be used again in the near future. This + * avoids retaining a large number of stale nested SPs. + */ + if (tdp_enabled && invalid_list && + child->role.guest_mode && !child->parent_ptes.val) + return kvm_mmu_prepare_zap_page(kvm, child, + invalid_list); + } + } else if (is_mmio_spte(pte)) { + mmu_spte_clear_no_track(spte); + } + return 0; +} + +static int kvm_mmu_page_unlink_children(struct kvm *kvm, + struct kvm_mmu_page *sp, + struct list_head *invalid_list) +{ + int zapped = 0; + unsigned i; + + for (i = 0; i < SPTE_ENT_PER_PAGE; ++i) + zapped += mmu_page_zap_pte(kvm, sp, sp->spt + i, invalid_list); + + return zapped; +} + +static void kvm_mmu_unlink_parents(struct kvm_mmu_page *sp) +{ + u64 *sptep; + struct rmap_iterator iter; + + while ((sptep = rmap_get_first(&sp->parent_ptes, &iter))) + drop_parent_pte(sp, sptep); +} + +static int mmu_zap_unsync_children(struct kvm *kvm, + struct kvm_mmu_page *parent, + struct list_head *invalid_list) +{ + int i, zapped = 0; + struct mmu_page_path parents; + struct kvm_mmu_pages pages; + + if (parent->role.level == PG_LEVEL_4K) + return 0; + + while (mmu_unsync_walk(parent, &pages)) { + struct kvm_mmu_page *sp; + + for_each_sp(pages, sp, parents, i) { + kvm_mmu_prepare_zap_page(kvm, sp, invalid_list); + mmu_pages_clear_parents(&parents); + zapped++; + } + } + + return zapped; +} + +static bool __kvm_mmu_prepare_zap_page(struct kvm *kvm, + struct kvm_mmu_page *sp, + struct list_head *invalid_list, + int *nr_zapped) +{ + bool list_unstable, zapped_root = false; + + lockdep_assert_held_write(&kvm->mmu_lock); + trace_kvm_mmu_prepare_zap_page(sp); + ++kvm->stat.mmu_shadow_zapped; + *nr_zapped = mmu_zap_unsync_children(kvm, sp, invalid_list); + *nr_zapped += kvm_mmu_page_unlink_children(kvm, sp, invalid_list); + kvm_mmu_unlink_parents(sp); + + /* Zapping children means active_mmu_pages has become unstable. */ + list_unstable = *nr_zapped; + + if (!sp->role.invalid && sp_has_gptes(sp)) + unaccount_shadowed(kvm, sp); + + if (sp->unsync) + kvm_unlink_unsync_page(kvm, sp); + if (!sp->root_count) { + /* Count self */ + (*nr_zapped)++; + + /* + * Already invalid pages (previously active roots) are not on + * the active page list. See list_del() in the "else" case of + * !sp->root_count. + */ + if (sp->role.invalid) + list_add(&sp->link, invalid_list); + else + list_move(&sp->link, invalid_list); + kvm_unaccount_mmu_page(kvm, sp); + } else { + /* + * Remove the active root from the active page list, the root + * will be explicitly freed when the root_count hits zero. + */ + list_del(&sp->link); + + /* + * Obsolete pages cannot be used on any vCPUs, see the comment + * in kvm_mmu_zap_all_fast(). Note, is_obsolete_sp() also + * treats invalid shadow pages as being obsolete. + */ + zapped_root = !is_obsolete_sp(kvm, sp); + } + + if (sp->lpage_disallowed) + unaccount_huge_nx_page(kvm, sp); + + sp->role.invalid = 1; + + /* + * Make the request to free obsolete roots after marking the root + * invalid, otherwise other vCPUs may not see it as invalid. + */ + if (zapped_root) + kvm_make_all_cpus_request(kvm, KVM_REQ_MMU_FREE_OBSOLETE_ROOTS); + return list_unstable; +} + +static bool kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp, + struct list_head *invalid_list) +{ + int nr_zapped; + + __kvm_mmu_prepare_zap_page(kvm, sp, invalid_list, &nr_zapped); + return nr_zapped; +} + +static void kvm_mmu_commit_zap_page(struct kvm *kvm, + struct list_head *invalid_list) +{ + struct kvm_mmu_page *sp, *nsp; + + if (list_empty(invalid_list)) + return; + + /* + * We need to make sure everyone sees our modifications to + * the page tables and see changes to vcpu->mode here. The barrier + * in the kvm_flush_remote_tlbs() achieves this. This pairs + * with vcpu_enter_guest and walk_shadow_page_lockless_begin/end. + * + * In addition, kvm_flush_remote_tlbs waits for all vcpus to exit + * guest mode and/or lockless shadow page table walks. + */ + kvm_flush_remote_tlbs(kvm); + + list_for_each_entry_safe(sp, nsp, invalid_list, link) { + WARN_ON(!sp->role.invalid || sp->root_count); + kvm_mmu_free_shadow_page(sp); + } +} + +static unsigned long kvm_mmu_zap_oldest_mmu_pages(struct kvm *kvm, + unsigned long nr_to_zap) +{ + unsigned long total_zapped = 0; + struct kvm_mmu_page *sp, *tmp; + LIST_HEAD(invalid_list); + bool unstable; + int nr_zapped; + + if (list_empty(&kvm->arch.active_mmu_pages)) + return 0; + +restart: + list_for_each_entry_safe_reverse(sp, tmp, &kvm->arch.active_mmu_pages, link) { + /* + * Don't zap active root pages, the page itself can't be freed + * and zapping it will just force vCPUs to realloc and reload. + */ + if (sp->root_count) + continue; + + unstable = __kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list, + &nr_zapped); + total_zapped += nr_zapped; + if (total_zapped >= nr_to_zap) + break; + + if (unstable) + goto restart; + } + + kvm_mmu_commit_zap_page(kvm, &invalid_list); + + kvm->stat.mmu_recycled += total_zapped; + return total_zapped; +} + +static inline unsigned long kvm_mmu_available_pages(struct kvm *kvm) +{ + if (kvm->arch.n_max_mmu_pages > kvm->arch.n_used_mmu_pages) + return kvm->arch.n_max_mmu_pages - + kvm->arch.n_used_mmu_pages; + + return 0; +} + +static int make_mmu_pages_available(struct kvm_vcpu *vcpu) +{ + unsigned long avail = kvm_mmu_available_pages(vcpu->kvm); + + if (likely(avail >= KVM_MIN_FREE_MMU_PAGES)) + return 0; + + kvm_mmu_zap_oldest_mmu_pages(vcpu->kvm, KVM_REFILL_PAGES - avail); + + /* + * Note, this check is intentionally soft, it only guarantees that one + * page is available, while the caller may end up allocating as many as + * four pages, e.g. for PAE roots or for 5-level paging. Temporarily + * exceeding the (arbitrary by default) limit will not harm the host, + * being too aggressive may unnecessarily kill the guest, and getting an + * exact count is far more trouble than it's worth, especially in the + * page fault paths. + */ + if (!kvm_mmu_available_pages(vcpu->kvm)) + return -ENOSPC; + return 0; +} + +/* + * Changing the number of mmu pages allocated to the vm + * Note: if goal_nr_mmu_pages is too small, you will get dead lock + */ +void kvm_mmu_change_mmu_pages(struct kvm *kvm, unsigned long goal_nr_mmu_pages) +{ + write_lock(&kvm->mmu_lock); + + if (kvm->arch.n_used_mmu_pages > goal_nr_mmu_pages) { + kvm_mmu_zap_oldest_mmu_pages(kvm, kvm->arch.n_used_mmu_pages - + goal_nr_mmu_pages); + + goal_nr_mmu_pages = kvm->arch.n_used_mmu_pages; + } + + kvm->arch.n_max_mmu_pages = goal_nr_mmu_pages; + + write_unlock(&kvm->mmu_lock); +} + +int kvm_mmu_unprotect_page(struct kvm *kvm, gfn_t gfn) +{ + struct kvm_mmu_page *sp; + LIST_HEAD(invalid_list); + int r; + + pgprintk("%s: looking for gfn %llx\n", __func__, gfn); + r = 0; + write_lock(&kvm->mmu_lock); + for_each_gfn_valid_sp_with_gptes(kvm, sp, gfn) { + pgprintk("%s: gfn %llx role %x\n", __func__, gfn, + sp->role.word); + r = 1; + kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list); + } + kvm_mmu_commit_zap_page(kvm, &invalid_list); + write_unlock(&kvm->mmu_lock); + + return r; +} + +static int kvm_mmu_unprotect_page_virt(struct kvm_vcpu *vcpu, gva_t gva) +{ + gpa_t gpa; + int r; + + if (vcpu->arch.mmu->root_role.direct) + return 0; + + gpa = kvm_mmu_gva_to_gpa_read(vcpu, gva, NULL); + + r = kvm_mmu_unprotect_page(vcpu->kvm, gpa >> PAGE_SHIFT); + + return r; +} + +static void kvm_unsync_page(struct kvm *kvm, struct kvm_mmu_page *sp) +{ + trace_kvm_mmu_unsync_page(sp); + ++kvm->stat.mmu_unsync; + sp->unsync = 1; + + kvm_mmu_mark_parents_unsync(sp); +} + +/* + * Attempt to unsync any shadow pages that can be reached by the specified gfn, + * KVM is creating a writable mapping for said gfn. Returns 0 if all pages + * were marked unsync (or if there is no shadow page), -EPERM if the SPTE must + * be write-protected. + */ +int mmu_try_to_unsync_pages(struct kvm *kvm, const struct kvm_memory_slot *slot, + gfn_t gfn, bool can_unsync, bool prefetch) +{ + struct kvm_mmu_page *sp; + bool locked = false; + + /* + * Force write-protection if the page is being tracked. Note, the page + * track machinery is used to write-protect upper-level shadow pages, + * i.e. this guards the role.level == 4K assertion below! + */ + if (kvm_slot_page_track_is_active(kvm, slot, gfn, KVM_PAGE_TRACK_WRITE)) + return -EPERM; + + /* + * The page is not write-tracked, mark existing shadow pages unsync + * unless KVM is synchronizing an unsync SP (can_unsync = false). In + * that case, KVM must complete emulation of the guest TLB flush before + * allowing shadow pages to become unsync (writable by the guest). + */ + for_each_gfn_valid_sp_with_gptes(kvm, sp, gfn) { + if (!can_unsync) + return -EPERM; + + if (sp->unsync) + continue; + + if (prefetch) + return -EEXIST; + + /* + * TDP MMU page faults require an additional spinlock as they + * run with mmu_lock held for read, not write, and the unsync + * logic is not thread safe. Take the spinklock regardless of + * the MMU type to avoid extra conditionals/parameters, there's + * no meaningful penalty if mmu_lock is held for write. + */ + if (!locked) { + locked = true; + spin_lock(&kvm->arch.mmu_unsync_pages_lock); + + /* + * Recheck after taking the spinlock, a different vCPU + * may have since marked the page unsync. A false + * positive on the unprotected check above is not + * possible as clearing sp->unsync _must_ hold mmu_lock + * for write, i.e. unsync cannot transition from 0->1 + * while this CPU holds mmu_lock for read (or write). + */ + if (READ_ONCE(sp->unsync)) + continue; + } + + WARN_ON(sp->role.level != PG_LEVEL_4K); + kvm_unsync_page(kvm, sp); + } + if (locked) + spin_unlock(&kvm->arch.mmu_unsync_pages_lock); + + /* + * We need to ensure that the marking of unsync pages is visible + * before the SPTE is updated to allow writes because + * kvm_mmu_sync_roots() checks the unsync flags without holding + * the MMU lock and so can race with this. If the SPTE was updated + * before the page had been marked as unsync-ed, something like the + * following could happen: + * + * CPU 1 CPU 2 + * --------------------------------------------------------------------- + * 1.2 Host updates SPTE + * to be writable + * 2.1 Guest writes a GPTE for GVA X. + * (GPTE being in the guest page table shadowed + * by the SP from CPU 1.) + * This reads SPTE during the page table walk. + * Since SPTE.W is read as 1, there is no + * fault. + * + * 2.2 Guest issues TLB flush. + * That causes a VM Exit. + * + * 2.3 Walking of unsync pages sees sp->unsync is + * false and skips the page. + * + * 2.4 Guest accesses GVA X. + * Since the mapping in the SP was not updated, + * so the old mapping for GVA X incorrectly + * gets used. + * 1.1 Host marks SP + * as unsync + * (sp->unsync = true) + * + * The write barrier below ensures that 1.1 happens before 1.2 and thus + * the situation in 2.4 does not arise. It pairs with the read barrier + * in is_unsync_root(), placed between 2.1's load of SPTE.W and 2.3. + */ + smp_wmb(); + + return 0; +} + +static int mmu_set_spte(struct kvm_vcpu *vcpu, struct kvm_memory_slot *slot, + u64 *sptep, unsigned int pte_access, gfn_t gfn, + kvm_pfn_t pfn, struct kvm_page_fault *fault) +{ + struct kvm_mmu_page *sp = sptep_to_sp(sptep); + int level = sp->role.level; + int was_rmapped = 0; + int ret = RET_PF_FIXED; + bool flush = false; + bool wrprot; + u64 spte; + + /* Prefetching always gets a writable pfn. */ + bool host_writable = !fault || fault->map_writable; + bool prefetch = !fault || fault->prefetch; + bool write_fault = fault && fault->write; + + pgprintk("%s: spte %llx write_fault %d gfn %llx\n", __func__, + *sptep, write_fault, gfn); + + if (unlikely(is_noslot_pfn(pfn))) { + vcpu->stat.pf_mmio_spte_created++; + mark_mmio_spte(vcpu, sptep, gfn, pte_access); + return RET_PF_EMULATE; + } + + if (is_shadow_present_pte(*sptep)) { + /* + * If we overwrite a PTE page pointer with a 2MB PMD, unlink + * the parent of the now unreachable PTE. + */ + if (level > PG_LEVEL_4K && !is_large_pte(*sptep)) { + struct kvm_mmu_page *child; + u64 pte = *sptep; + + child = to_shadow_page(pte & SPTE_BASE_ADDR_MASK); + drop_parent_pte(child, sptep); + flush = true; + } else if (pfn != spte_to_pfn(*sptep)) { + pgprintk("hfn old %llx new %llx\n", + spte_to_pfn(*sptep), pfn); + drop_spte(vcpu->kvm, sptep); + flush = true; + } else + was_rmapped = 1; + } + + wrprot = make_spte(vcpu, sp, slot, pte_access, gfn, pfn, *sptep, prefetch, + true, host_writable, &spte); + + if (*sptep == spte) { + ret = RET_PF_SPURIOUS; + } else { + flush |= mmu_spte_update(sptep, spte); + trace_kvm_mmu_set_spte(level, gfn, sptep); + } + + if (wrprot) { + if (write_fault) + ret = RET_PF_EMULATE; + } + + if (flush) + kvm_flush_remote_tlbs_with_address(vcpu->kvm, gfn, + KVM_PAGES_PER_HPAGE(level)); + + pgprintk("%s: setting spte %llx\n", __func__, *sptep); + + if (!was_rmapped) { + WARN_ON_ONCE(ret == RET_PF_SPURIOUS); + rmap_add(vcpu, slot, sptep, gfn, pte_access); + } else { + /* Already rmapped but the pte_access bits may have changed. */ + kvm_mmu_page_set_access(sp, spte_index(sptep), pte_access); + } + + return ret; +} + +static int direct_pte_prefetch_many(struct kvm_vcpu *vcpu, + struct kvm_mmu_page *sp, + u64 *start, u64 *end) +{ + struct page *pages[PTE_PREFETCH_NUM]; + struct kvm_memory_slot *slot; + unsigned int access = sp->role.access; + int i, ret; + gfn_t gfn; + + gfn = kvm_mmu_page_get_gfn(sp, spte_index(start)); + slot = gfn_to_memslot_dirty_bitmap(vcpu, gfn, access & ACC_WRITE_MASK); + if (!slot) + return -1; + + ret = gfn_to_page_many_atomic(slot, gfn, pages, end - start); + if (ret <= 0) + return -1; + + for (i = 0; i < ret; i++, gfn++, start++) { + mmu_set_spte(vcpu, slot, start, access, gfn, + page_to_pfn(pages[i]), NULL); + put_page(pages[i]); + } + + return 0; +} + +static void __direct_pte_prefetch(struct kvm_vcpu *vcpu, + struct kvm_mmu_page *sp, u64 *sptep) +{ + u64 *spte, *start = NULL; + int i; + + WARN_ON(!sp->role.direct); + + i = spte_index(sptep) & ~(PTE_PREFETCH_NUM - 1); + spte = sp->spt + i; + + for (i = 0; i < PTE_PREFETCH_NUM; i++, spte++) { + if (is_shadow_present_pte(*spte) || spte == sptep) { + if (!start) + continue; + if (direct_pte_prefetch_many(vcpu, sp, start, spte) < 0) + return; + start = NULL; + } else if (!start) + start = spte; + } + if (start) + direct_pte_prefetch_many(vcpu, sp, start, spte); +} + +static void direct_pte_prefetch(struct kvm_vcpu *vcpu, u64 *sptep) +{ + struct kvm_mmu_page *sp; + + sp = sptep_to_sp(sptep); + + /* + * Without accessed bits, there's no way to distinguish between + * actually accessed translations and prefetched, so disable pte + * prefetch if accessed bits aren't available. + */ + if (sp_ad_disabled(sp)) + return; + + if (sp->role.level > PG_LEVEL_4K) + return; + + /* + * If addresses are being invalidated, skip prefetching to avoid + * accidentally prefetching those addresses. + */ + if (unlikely(vcpu->kvm->mmu_invalidate_in_progress)) + return; + + __direct_pte_prefetch(vcpu, sp, sptep); +} + +/* + * Lookup the mapping level for @gfn in the current mm. + * + * WARNING! Use of host_pfn_mapping_level() requires the caller and the end + * consumer to be tied into KVM's handlers for MMU notifier events! + * + * There are several ways to safely use this helper: + * + * - Check mmu_invalidate_retry_hva() after grabbing the mapping level, before + * consuming it. In this case, mmu_lock doesn't need to be held during the + * lookup, but it does need to be held while checking the MMU notifier. + * + * - Hold mmu_lock AND ensure there is no in-progress MMU notifier invalidation + * event for the hva. This can be done by explicit checking the MMU notifier + * or by ensuring that KVM already has a valid mapping that covers the hva. + * + * - Do not use the result to install new mappings, e.g. use the host mapping + * level only to decide whether or not to zap an entry. In this case, it's + * not required to hold mmu_lock (though it's highly likely the caller will + * want to hold mmu_lock anyways, e.g. to modify SPTEs). + * + * Note! The lookup can still race with modifications to host page tables, but + * the above "rules" ensure KVM will not _consume_ the result of the walk if a + * race with the primary MMU occurs. + */ +static int host_pfn_mapping_level(struct kvm *kvm, gfn_t gfn, + const struct kvm_memory_slot *slot) +{ + int level = PG_LEVEL_4K; + unsigned long hva; + unsigned long flags; + pgd_t pgd; + p4d_t p4d; + pud_t pud; + pmd_t pmd; + + /* + * Note, using the already-retrieved memslot and __gfn_to_hva_memslot() + * is not solely for performance, it's also necessary to avoid the + * "writable" check in __gfn_to_hva_many(), which will always fail on + * read-only memslots due to gfn_to_hva() assuming writes. Earlier + * page fault steps have already verified the guest isn't writing a + * read-only memslot. + */ + hva = __gfn_to_hva_memslot(slot, gfn); + + /* + * Disable IRQs to prevent concurrent tear down of host page tables, + * e.g. if the primary MMU promotes a P*D to a huge page and then frees + * the original page table. + */ + local_irq_save(flags); + + /* + * Read each entry once. As above, a non-leaf entry can be promoted to + * a huge page _during_ this walk. Re-reading the entry could send the + * walk into the weeks, e.g. p*d_large() returns false (sees the old + * value) and then p*d_offset() walks into the target huge page instead + * of the old page table (sees the new value). + */ + pgd = READ_ONCE(*pgd_offset(kvm->mm, hva)); + if (pgd_none(pgd)) + goto out; + + p4d = READ_ONCE(*p4d_offset(&pgd, hva)); + if (p4d_none(p4d) || !p4d_present(p4d)) + goto out; + + pud = READ_ONCE(*pud_offset(&p4d, hva)); + if (pud_none(pud) || !pud_present(pud)) + goto out; + + if (pud_large(pud)) { + level = PG_LEVEL_1G; + goto out; + } + + pmd = READ_ONCE(*pmd_offset(&pud, hva)); + if (pmd_none(pmd) || !pmd_present(pmd)) + goto out; + + if (pmd_large(pmd)) + level = PG_LEVEL_2M; + +out: + local_irq_restore(flags); + return level; +} + +int kvm_mmu_max_mapping_level(struct kvm *kvm, + const struct kvm_memory_slot *slot, gfn_t gfn, + int max_level) +{ + struct kvm_lpage_info *linfo; + int host_level; + + max_level = min(max_level, max_huge_page_level); + for ( ; max_level > PG_LEVEL_4K; max_level--) { + linfo = lpage_info_slot(gfn, slot, max_level); + if (!linfo->disallow_lpage) + break; + } + + if (max_level == PG_LEVEL_4K) + return PG_LEVEL_4K; + + host_level = host_pfn_mapping_level(kvm, gfn, slot); + return min(host_level, max_level); +} + +void kvm_mmu_hugepage_adjust(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) +{ + struct kvm_memory_slot *slot = fault->slot; + kvm_pfn_t mask; + + fault->huge_page_disallowed = fault->exec && fault->nx_huge_page_workaround_enabled; + + if (unlikely(fault->max_level == PG_LEVEL_4K)) + return; + + if (is_error_noslot_pfn(fault->pfn)) + return; + + if (kvm_slot_dirty_track_enabled(slot)) + return; + + /* + * Enforce the iTLB multihit workaround after capturing the requested + * level, which will be used to do precise, accurate accounting. + */ + fault->req_level = kvm_mmu_max_mapping_level(vcpu->kvm, slot, + fault->gfn, fault->max_level); + if (fault->req_level == PG_LEVEL_4K || fault->huge_page_disallowed) + return; + + /* + * mmu_invalidate_retry() was successful and mmu_lock is held, so + * the pmd can't be split from under us. + */ + fault->goal_level = fault->req_level; + mask = KVM_PAGES_PER_HPAGE(fault->goal_level) - 1; + VM_BUG_ON((fault->gfn & mask) != (fault->pfn & mask)); + fault->pfn &= ~mask; +} + +void disallowed_hugepage_adjust(struct kvm_page_fault *fault, u64 spte, int cur_level) +{ + if (cur_level > PG_LEVEL_4K && + cur_level == fault->goal_level && + is_shadow_present_pte(spte) && + !is_large_pte(spte)) { + /* + * A small SPTE exists for this pfn, but FNAME(fetch) + * and __direct_map would like to create a large PTE + * instead: just force them to go down another level, + * patching back for them into pfn the next 9 bits of + * the address. + */ + u64 page_mask = KVM_PAGES_PER_HPAGE(cur_level) - + KVM_PAGES_PER_HPAGE(cur_level - 1); + fault->pfn |= fault->gfn & page_mask; + fault->goal_level--; + } +} + +static int __direct_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) +{ + struct kvm_shadow_walk_iterator it; + struct kvm_mmu_page *sp; + int ret; + gfn_t base_gfn = fault->gfn; + + kvm_mmu_hugepage_adjust(vcpu, fault); + + trace_kvm_mmu_spte_requested(fault); + for_each_shadow_entry(vcpu, fault->addr, it) { + /* + * We cannot overwrite existing page tables with an NX + * large page, as the leaf could be executable. + */ + if (fault->nx_huge_page_workaround_enabled) + disallowed_hugepage_adjust(fault, *it.sptep, it.level); + + base_gfn = fault->gfn & ~(KVM_PAGES_PER_HPAGE(it.level) - 1); + if (it.level == fault->goal_level) + break; + + sp = kvm_mmu_get_child_sp(vcpu, it.sptep, base_gfn, true, ACC_ALL); + if (sp == ERR_PTR(-EEXIST)) + continue; + + link_shadow_page(vcpu, it.sptep, sp); + if (fault->is_tdp && fault->huge_page_disallowed && + fault->req_level >= it.level) + account_huge_nx_page(vcpu->kvm, sp); + } + + if (WARN_ON_ONCE(it.level != fault->goal_level)) + return -EFAULT; + + ret = mmu_set_spte(vcpu, fault->slot, it.sptep, ACC_ALL, + base_gfn, fault->pfn, fault); + if (ret == RET_PF_SPURIOUS) + return ret; + + direct_pte_prefetch(vcpu, it.sptep); + return ret; +} + +static void kvm_send_hwpoison_signal(unsigned long address, struct task_struct *tsk) +{ + send_sig_mceerr(BUS_MCEERR_AR, (void __user *)address, PAGE_SHIFT, tsk); +} + +static int kvm_handle_bad_page(struct kvm_vcpu *vcpu, gfn_t gfn, kvm_pfn_t pfn) +{ + /* + * Do not cache the mmio info caused by writing the readonly gfn + * into the spte otherwise read access on readonly gfn also can + * caused mmio page fault and treat it as mmio access. + */ + if (pfn == KVM_PFN_ERR_RO_FAULT) + return RET_PF_EMULATE; + + if (pfn == KVM_PFN_ERR_HWPOISON) { + kvm_send_hwpoison_signal(kvm_vcpu_gfn_to_hva(vcpu, gfn), current); + return RET_PF_RETRY; + } + + return -EFAULT; +} + +static int handle_abnormal_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault, + unsigned int access) +{ + /* The pfn is invalid, report the error! */ + if (unlikely(is_error_pfn(fault->pfn))) + return kvm_handle_bad_page(vcpu, fault->gfn, fault->pfn); + + if (unlikely(!fault->slot)) { + gva_t gva = fault->is_tdp ? 0 : fault->addr; + + vcpu_cache_mmio_info(vcpu, gva, fault->gfn, + access & shadow_mmio_access_mask); + /* + * If MMIO caching is disabled, emulate immediately without + * touching the shadow page tables as attempting to install an + * MMIO SPTE will just be an expensive nop. Do not cache MMIO + * whose gfn is greater than host.MAXPHYADDR, any guest that + * generates such gfns is running nested and is being tricked + * by L0 userspace (you can observe gfn > L1.MAXPHYADDR if + * and only if L1's MAXPHYADDR is inaccurate with respect to + * the hardware's). + */ + if (unlikely(!enable_mmio_caching) || + unlikely(fault->gfn > kvm_mmu_max_gfn())) + return RET_PF_EMULATE; + } + + return RET_PF_CONTINUE; +} + +static bool page_fault_can_be_fast(struct kvm_page_fault *fault) +{ + /* + * Page faults with reserved bits set, i.e. faults on MMIO SPTEs, only + * reach the common page fault handler if the SPTE has an invalid MMIO + * generation number. Refreshing the MMIO generation needs to go down + * the slow path. Note, EPT Misconfigs do NOT set the PRESENT flag! + */ + if (fault->rsvd) + return false; + + /* + * #PF can be fast if: + * + * 1. The shadow page table entry is not present and A/D bits are + * disabled _by KVM_, which could mean that the fault is potentially + * caused by access tracking (if enabled). If A/D bits are enabled + * by KVM, but disabled by L1 for L2, KVM is forced to disable A/D + * bits for L2 and employ access tracking, but the fast page fault + * mechanism only supports direct MMUs. + * 2. The shadow page table entry is present, the access is a write, + * and no reserved bits are set (MMIO SPTEs cannot be "fixed"), i.e. + * the fault was caused by a write-protection violation. If the + * SPTE is MMU-writable (determined later), the fault can be fixed + * by setting the Writable bit, which can be done out of mmu_lock. + */ + if (!fault->present) + return !kvm_ad_enabled(); + + /* + * Note, instruction fetches and writes are mutually exclusive, ignore + * the "exec" flag. + */ + return fault->write; +} + +/* + * Returns true if the SPTE was fixed successfully. Otherwise, + * someone else modified the SPTE from its original value. + */ +static bool +fast_pf_fix_direct_spte(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault, + u64 *sptep, u64 old_spte, u64 new_spte) +{ + /* + * Theoretically we could also set dirty bit (and flush TLB) here in + * order to eliminate unnecessary PML logging. See comments in + * set_spte. But fast_page_fault is very unlikely to happen with PML + * enabled, so we do not do this. This might result in the same GPA + * to be logged in PML buffer again when the write really happens, and + * eventually to be called by mark_page_dirty twice. But it's also no + * harm. This also avoids the TLB flush needed after setting dirty bit + * so non-PML cases won't be impacted. + * + * Compare with set_spte where instead shadow_dirty_mask is set. + */ + if (!try_cmpxchg64(sptep, &old_spte, new_spte)) + return false; + + if (is_writable_pte(new_spte) && !is_writable_pte(old_spte)) + mark_page_dirty_in_slot(vcpu->kvm, fault->slot, fault->gfn); + + return true; +} + +static bool is_access_allowed(struct kvm_page_fault *fault, u64 spte) +{ + if (fault->exec) + return is_executable_pte(spte); + + if (fault->write) + return is_writable_pte(spte); + + /* Fault was on Read access */ + return spte & PT_PRESENT_MASK; +} + +/* + * Returns the last level spte pointer of the shadow page walk for the given + * gpa, and sets *spte to the spte value. This spte may be non-preset. If no + * walk could be performed, returns NULL and *spte does not contain valid data. + * + * Contract: + * - Must be called between walk_shadow_page_lockless_{begin,end}. + * - The returned sptep must not be used after walk_shadow_page_lockless_end. + */ +static u64 *fast_pf_get_last_sptep(struct kvm_vcpu *vcpu, gpa_t gpa, u64 *spte) +{ + struct kvm_shadow_walk_iterator iterator; + u64 old_spte; + u64 *sptep = NULL; + + for_each_shadow_entry_lockless(vcpu, gpa, iterator, old_spte) { + sptep = iterator.sptep; + *spte = old_spte; + } + + return sptep; +} + +/* + * Returns one of RET_PF_INVALID, RET_PF_FIXED or RET_PF_SPURIOUS. + */ +static int fast_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) +{ + struct kvm_mmu_page *sp; + int ret = RET_PF_INVALID; + u64 spte = 0ull; + u64 *sptep = NULL; + uint retry_count = 0; + + if (!page_fault_can_be_fast(fault)) + return ret; + + walk_shadow_page_lockless_begin(vcpu); + + do { + u64 new_spte; + + if (is_tdp_mmu(vcpu->arch.mmu)) + sptep = kvm_tdp_mmu_fast_pf_get_last_sptep(vcpu, fault->addr, &spte); + else + sptep = fast_pf_get_last_sptep(vcpu, fault->addr, &spte); + + if (!is_shadow_present_pte(spte)) + break; + + sp = sptep_to_sp(sptep); + if (!is_last_spte(spte, sp->role.level)) + break; + + /* + * Check whether the memory access that caused the fault would + * still cause it if it were to be performed right now. If not, + * then this is a spurious fault caused by TLB lazily flushed, + * or some other CPU has already fixed the PTE after the + * current CPU took the fault. + * + * Need not check the access of upper level table entries since + * they are always ACC_ALL. + */ + if (is_access_allowed(fault, spte)) { + ret = RET_PF_SPURIOUS; + break; + } + + new_spte = spte; + + /* + * KVM only supports fixing page faults outside of MMU lock for + * direct MMUs, nested MMUs are always indirect, and KVM always + * uses A/D bits for non-nested MMUs. Thus, if A/D bits are + * enabled, the SPTE can't be an access-tracked SPTE. + */ + if (unlikely(!kvm_ad_enabled()) && is_access_track_spte(spte)) + new_spte = restore_acc_track_spte(new_spte); + + /* + * To keep things simple, only SPTEs that are MMU-writable can + * be made fully writable outside of mmu_lock, e.g. only SPTEs + * that were write-protected for dirty-logging or access + * tracking are handled here. Don't bother checking if the + * SPTE is writable to prioritize running with A/D bits enabled. + * The is_access_allowed() check above handles the common case + * of the fault being spurious, and the SPTE is known to be + * shadow-present, i.e. except for access tracking restoration + * making the new SPTE writable, the check is wasteful. + */ + if (fault->write && is_mmu_writable_spte(spte)) { + new_spte |= PT_WRITABLE_MASK; + + /* + * Do not fix write-permission on the large spte when + * dirty logging is enabled. Since we only dirty the + * first page into the dirty-bitmap in + * fast_pf_fix_direct_spte(), other pages are missed + * if its slot has dirty logging enabled. + * + * Instead, we let the slow page fault path create a + * normal spte to fix the access. + */ + if (sp->role.level > PG_LEVEL_4K && + kvm_slot_dirty_track_enabled(fault->slot)) + break; + } + + /* Verify that the fault can be handled in the fast path */ + if (new_spte == spte || + !is_access_allowed(fault, new_spte)) + break; + + /* + * Currently, fast page fault only works for direct mapping + * since the gfn is not stable for indirect shadow page. See + * Documentation/virt/kvm/locking.rst to get more detail. + */ + if (fast_pf_fix_direct_spte(vcpu, fault, sptep, spte, new_spte)) { + ret = RET_PF_FIXED; + break; + } + + if (++retry_count > 4) { + printk_once(KERN_WARNING + "kvm: Fast #PF retrying more than 4 times.\n"); + break; + } + + } while (true); + + trace_fast_page_fault(vcpu, fault, sptep, spte, ret); + walk_shadow_page_lockless_end(vcpu); + + if (ret != RET_PF_INVALID) + vcpu->stat.pf_fast++; + + return ret; +} + +static void mmu_free_root_page(struct kvm *kvm, hpa_t *root_hpa, + struct list_head *invalid_list) +{ + struct kvm_mmu_page *sp; + + if (!VALID_PAGE(*root_hpa)) + return; + + sp = to_shadow_page(*root_hpa & SPTE_BASE_ADDR_MASK); + if (WARN_ON(!sp)) + return; + + if (is_tdp_mmu_page(sp)) + kvm_tdp_mmu_put_root(kvm, sp, false); + else if (!--sp->root_count && sp->role.invalid) + kvm_mmu_prepare_zap_page(kvm, sp, invalid_list); + + *root_hpa = INVALID_PAGE; +} + +/* roots_to_free must be some combination of the KVM_MMU_ROOT_* flags */ +void kvm_mmu_free_roots(struct kvm *kvm, struct kvm_mmu *mmu, + ulong roots_to_free) +{ + int i; + LIST_HEAD(invalid_list); + bool free_active_root; + + BUILD_BUG_ON(KVM_MMU_NUM_PREV_ROOTS >= BITS_PER_LONG); + + /* Before acquiring the MMU lock, see if we need to do any real work. */ + free_active_root = (roots_to_free & KVM_MMU_ROOT_CURRENT) + && VALID_PAGE(mmu->root.hpa); + + if (!free_active_root) { + for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) + if ((roots_to_free & KVM_MMU_ROOT_PREVIOUS(i)) && + VALID_PAGE(mmu->prev_roots[i].hpa)) + break; + + if (i == KVM_MMU_NUM_PREV_ROOTS) + return; + } + + write_lock(&kvm->mmu_lock); + + for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) + if (roots_to_free & KVM_MMU_ROOT_PREVIOUS(i)) + mmu_free_root_page(kvm, &mmu->prev_roots[i].hpa, + &invalid_list); + + if (free_active_root) { + if (to_shadow_page(mmu->root.hpa)) { + mmu_free_root_page(kvm, &mmu->root.hpa, &invalid_list); + } else if (mmu->pae_root) { + for (i = 0; i < 4; ++i) { + if (!IS_VALID_PAE_ROOT(mmu->pae_root[i])) + continue; + + mmu_free_root_page(kvm, &mmu->pae_root[i], + &invalid_list); + mmu->pae_root[i] = INVALID_PAE_ROOT; + } + } + mmu->root.hpa = INVALID_PAGE; + mmu->root.pgd = 0; + } + + kvm_mmu_commit_zap_page(kvm, &invalid_list); + write_unlock(&kvm->mmu_lock); +} +EXPORT_SYMBOL_GPL(kvm_mmu_free_roots); + +void kvm_mmu_free_guest_mode_roots(struct kvm *kvm, struct kvm_mmu *mmu) +{ + unsigned long roots_to_free = 0; + hpa_t root_hpa; + int i; + + /* + * This should not be called while L2 is active, L2 can't invalidate + * _only_ its own roots, e.g. INVVPID unconditionally exits. + */ + WARN_ON_ONCE(mmu->root_role.guest_mode); + + for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) { + root_hpa = mmu->prev_roots[i].hpa; + if (!VALID_PAGE(root_hpa)) + continue; + + if (!to_shadow_page(root_hpa) || + to_shadow_page(root_hpa)->role.guest_mode) + roots_to_free |= KVM_MMU_ROOT_PREVIOUS(i); + } + + kvm_mmu_free_roots(kvm, mmu, roots_to_free); +} +EXPORT_SYMBOL_GPL(kvm_mmu_free_guest_mode_roots); + + +static int mmu_check_root(struct kvm_vcpu *vcpu, gfn_t root_gfn) +{ + int ret = 0; + + if (!kvm_vcpu_is_visible_gfn(vcpu, root_gfn)) { + kvm_make_request(KVM_REQ_TRIPLE_FAULT, vcpu); + ret = 1; + } + + return ret; +} + +static hpa_t mmu_alloc_root(struct kvm_vcpu *vcpu, gfn_t gfn, int quadrant, + u8 level) +{ + union kvm_mmu_page_role role = vcpu->arch.mmu->root_role; + struct kvm_mmu_page *sp; + + role.level = level; + role.quadrant = quadrant; + + WARN_ON_ONCE(quadrant && !role.has_4_byte_gpte); + WARN_ON_ONCE(role.direct && role.has_4_byte_gpte); + + sp = kvm_mmu_get_shadow_page(vcpu, gfn, role); + ++sp->root_count; + + return __pa(sp->spt); +} + +static int mmu_alloc_direct_roots(struct kvm_vcpu *vcpu) +{ + struct kvm_mmu *mmu = vcpu->arch.mmu; + u8 shadow_root_level = mmu->root_role.level; + hpa_t root; + unsigned i; + int r; + + write_lock(&vcpu->kvm->mmu_lock); + r = make_mmu_pages_available(vcpu); + if (r < 0) + goto out_unlock; + + if (is_tdp_mmu_enabled(vcpu->kvm)) { + root = kvm_tdp_mmu_get_vcpu_root_hpa(vcpu); + mmu->root.hpa = root; + } else if (shadow_root_level >= PT64_ROOT_4LEVEL) { + root = mmu_alloc_root(vcpu, 0, 0, shadow_root_level); + mmu->root.hpa = root; + } else if (shadow_root_level == PT32E_ROOT_LEVEL) { + if (WARN_ON_ONCE(!mmu->pae_root)) { + r = -EIO; + goto out_unlock; + } + + for (i = 0; i < 4; ++i) { + WARN_ON_ONCE(IS_VALID_PAE_ROOT(mmu->pae_root[i])); + + root = mmu_alloc_root(vcpu, i << (30 - PAGE_SHIFT), 0, + PT32_ROOT_LEVEL); + mmu->pae_root[i] = root | PT_PRESENT_MASK | + shadow_me_value; + } + mmu->root.hpa = __pa(mmu->pae_root); + } else { + WARN_ONCE(1, "Bad TDP root level = %d\n", shadow_root_level); + r = -EIO; + goto out_unlock; + } + + /* root.pgd is ignored for direct MMUs. */ + mmu->root.pgd = 0; +out_unlock: + write_unlock(&vcpu->kvm->mmu_lock); + return r; +} + +static int mmu_first_shadow_root_alloc(struct kvm *kvm) +{ + struct kvm_memslots *slots; + struct kvm_memory_slot *slot; + int r = 0, i, bkt; + + /* + * Check if this is the first shadow root being allocated before + * taking the lock. + */ + if (kvm_shadow_root_allocated(kvm)) + return 0; + + mutex_lock(&kvm->slots_arch_lock); + + /* Recheck, under the lock, whether this is the first shadow root. */ + if (kvm_shadow_root_allocated(kvm)) + goto out_unlock; + + /* + * Check if anything actually needs to be allocated, e.g. all metadata + * will be allocated upfront if TDP is disabled. + */ + if (kvm_memslots_have_rmaps(kvm) && + kvm_page_track_write_tracking_enabled(kvm)) + goto out_success; + + for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) { + slots = __kvm_memslots(kvm, i); + kvm_for_each_memslot(slot, bkt, slots) { + /* + * Both of these functions are no-ops if the target is + * already allocated, so unconditionally calling both + * is safe. Intentionally do NOT free allocations on + * failure to avoid having to track which allocations + * were made now versus when the memslot was created. + * The metadata is guaranteed to be freed when the slot + * is freed, and will be kept/used if userspace retries + * KVM_RUN instead of killing the VM. + */ + r = memslot_rmap_alloc(slot, slot->npages); + if (r) + goto out_unlock; + r = kvm_page_track_write_tracking_alloc(slot); + if (r) + goto out_unlock; + } + } + + /* + * Ensure that shadow_root_allocated becomes true strictly after + * all the related pointers are set. + */ +out_success: + smp_store_release(&kvm->arch.shadow_root_allocated, true); + +out_unlock: + mutex_unlock(&kvm->slots_arch_lock); + return r; +} + +static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu) +{ + struct kvm_mmu *mmu = vcpu->arch.mmu; + u64 pdptrs[4], pm_mask; + gfn_t root_gfn, root_pgd; + int quadrant, i, r; + hpa_t root; + + root_pgd = kvm_mmu_get_guest_pgd(vcpu, mmu); + root_gfn = root_pgd >> PAGE_SHIFT; + + if (mmu_check_root(vcpu, root_gfn)) + return 1; + + /* + * On SVM, reading PDPTRs might access guest memory, which might fault + * and thus might sleep. Grab the PDPTRs before acquiring mmu_lock. + */ + if (mmu->cpu_role.base.level == PT32E_ROOT_LEVEL) { + for (i = 0; i < 4; ++i) { + pdptrs[i] = mmu->get_pdptr(vcpu, i); + if (!(pdptrs[i] & PT_PRESENT_MASK)) + continue; + + if (mmu_check_root(vcpu, pdptrs[i] >> PAGE_SHIFT)) + return 1; + } + } + + r = mmu_first_shadow_root_alloc(vcpu->kvm); + if (r) + return r; + + write_lock(&vcpu->kvm->mmu_lock); + r = make_mmu_pages_available(vcpu); + if (r < 0) + goto out_unlock; + + /* + * Do we shadow a long mode page table? If so we need to + * write-protect the guests page table root. + */ + if (mmu->cpu_role.base.level >= PT64_ROOT_4LEVEL) { + root = mmu_alloc_root(vcpu, root_gfn, 0, + mmu->root_role.level); + mmu->root.hpa = root; + goto set_root_pgd; + } + + if (WARN_ON_ONCE(!mmu->pae_root)) { + r = -EIO; + goto out_unlock; + } + + /* + * We shadow a 32 bit page table. This may be a legacy 2-level + * or a PAE 3-level page table. In either case we need to be aware that + * the shadow page table may be a PAE or a long mode page table. + */ + pm_mask = PT_PRESENT_MASK | shadow_me_value; + if (mmu->root_role.level >= PT64_ROOT_4LEVEL) { + pm_mask |= PT_ACCESSED_MASK | PT_WRITABLE_MASK | PT_USER_MASK; + + if (WARN_ON_ONCE(!mmu->pml4_root)) { + r = -EIO; + goto out_unlock; + } + mmu->pml4_root[0] = __pa(mmu->pae_root) | pm_mask; + + if (mmu->root_role.level == PT64_ROOT_5LEVEL) { + if (WARN_ON_ONCE(!mmu->pml5_root)) { + r = -EIO; + goto out_unlock; + } + mmu->pml5_root[0] = __pa(mmu->pml4_root) | pm_mask; + } + } + + for (i = 0; i < 4; ++i) { + WARN_ON_ONCE(IS_VALID_PAE_ROOT(mmu->pae_root[i])); + + if (mmu->cpu_role.base.level == PT32E_ROOT_LEVEL) { + if (!(pdptrs[i] & PT_PRESENT_MASK)) { + mmu->pae_root[i] = INVALID_PAE_ROOT; + continue; + } + root_gfn = pdptrs[i] >> PAGE_SHIFT; + } + + /* + * If shadowing 32-bit non-PAE page tables, each PAE page + * directory maps one quarter of the guest's non-PAE page + * directory. Othwerise each PAE page direct shadows one guest + * PAE page directory so that quadrant should be 0. + */ + quadrant = (mmu->cpu_role.base.level == PT32_ROOT_LEVEL) ? i : 0; + + root = mmu_alloc_root(vcpu, root_gfn, quadrant, PT32_ROOT_LEVEL); + mmu->pae_root[i] = root | pm_mask; + } + + if (mmu->root_role.level == PT64_ROOT_5LEVEL) + mmu->root.hpa = __pa(mmu->pml5_root); + else if (mmu->root_role.level == PT64_ROOT_4LEVEL) + mmu->root.hpa = __pa(mmu->pml4_root); + else + mmu->root.hpa = __pa(mmu->pae_root); + +set_root_pgd: + mmu->root.pgd = root_pgd; +out_unlock: + write_unlock(&vcpu->kvm->mmu_lock); + + return r; +} + +static int mmu_alloc_special_roots(struct kvm_vcpu *vcpu) +{ + struct kvm_mmu *mmu = vcpu->arch.mmu; + bool need_pml5 = mmu->root_role.level > PT64_ROOT_4LEVEL; + u64 *pml5_root = NULL; + u64 *pml4_root = NULL; + u64 *pae_root; + + /* + * When shadowing 32-bit or PAE NPT with 64-bit NPT, the PML4 and PDP + * tables are allocated and initialized at root creation as there is no + * equivalent level in the guest's NPT to shadow. Allocate the tables + * on demand, as running a 32-bit L1 VMM on 64-bit KVM is very rare. + */ + if (mmu->root_role.direct || + mmu->cpu_role.base.level >= PT64_ROOT_4LEVEL || + mmu->root_role.level < PT64_ROOT_4LEVEL) + return 0; + + /* + * NPT, the only paging mode that uses this horror, uses a fixed number + * of levels for the shadow page tables, e.g. all MMUs are 4-level or + * all MMus are 5-level. Thus, this can safely require that pml5_root + * is allocated if the other roots are valid and pml5 is needed, as any + * prior MMU would also have required pml5. + */ + if (mmu->pae_root && mmu->pml4_root && (!need_pml5 || mmu->pml5_root)) + return 0; + + /* + * The special roots should always be allocated in concert. Yell and + * bail if KVM ends up in a state where only one of the roots is valid. + */ + if (WARN_ON_ONCE(!tdp_enabled || mmu->pae_root || mmu->pml4_root || + (need_pml5 && mmu->pml5_root))) + return -EIO; + + /* + * Unlike 32-bit NPT, the PDP table doesn't need to be in low mem, and + * doesn't need to be decrypted. + */ + pae_root = (void *)get_zeroed_page(GFP_KERNEL_ACCOUNT); + if (!pae_root) + return -ENOMEM; + +#ifdef CONFIG_X86_64 + pml4_root = (void *)get_zeroed_page(GFP_KERNEL_ACCOUNT); + if (!pml4_root) + goto err_pml4; + + if (need_pml5) { + pml5_root = (void *)get_zeroed_page(GFP_KERNEL_ACCOUNT); + if (!pml5_root) + goto err_pml5; + } +#endif + + mmu->pae_root = pae_root; + mmu->pml4_root = pml4_root; + mmu->pml5_root = pml5_root; + + return 0; + +#ifdef CONFIG_X86_64 +err_pml5: + free_page((unsigned long)pml4_root); +err_pml4: + free_page((unsigned long)pae_root); + return -ENOMEM; +#endif +} + +static bool is_unsync_root(hpa_t root) +{ + struct kvm_mmu_page *sp; + + if (!VALID_PAGE(root)) + return false; + + /* + * The read barrier orders the CPU's read of SPTE.W during the page table + * walk before the reads of sp->unsync/sp->unsync_children here. + * + * Even if another CPU was marking the SP as unsync-ed simultaneously, + * any guest page table changes are not guaranteed to be visible anyway + * until this VCPU issues a TLB flush strictly after those changes are + * made. We only need to ensure that the other CPU sets these flags + * before any actual changes to the page tables are made. The comments + * in mmu_try_to_unsync_pages() describe what could go wrong if this + * requirement isn't satisfied. + */ + smp_rmb(); + sp = to_shadow_page(root); + + /* + * PAE roots (somewhat arbitrarily) aren't backed by shadow pages, the + * PDPTEs for a given PAE root need to be synchronized individually. + */ + if (WARN_ON_ONCE(!sp)) + return false; + + if (sp->unsync || sp->unsync_children) + return true; + + return false; +} + +void kvm_mmu_sync_roots(struct kvm_vcpu *vcpu) +{ + int i; + struct kvm_mmu_page *sp; + + if (vcpu->arch.mmu->root_role.direct) + return; + + if (!VALID_PAGE(vcpu->arch.mmu->root.hpa)) + return; + + vcpu_clear_mmio_info(vcpu, MMIO_GVA_ANY); + + if (vcpu->arch.mmu->cpu_role.base.level >= PT64_ROOT_4LEVEL) { + hpa_t root = vcpu->arch.mmu->root.hpa; + sp = to_shadow_page(root); + + if (!is_unsync_root(root)) + return; + + write_lock(&vcpu->kvm->mmu_lock); + mmu_sync_children(vcpu, sp, true); + write_unlock(&vcpu->kvm->mmu_lock); + return; + } + + write_lock(&vcpu->kvm->mmu_lock); + + for (i = 0; i < 4; ++i) { + hpa_t root = vcpu->arch.mmu->pae_root[i]; + + if (IS_VALID_PAE_ROOT(root)) { + root &= SPTE_BASE_ADDR_MASK; + sp = to_shadow_page(root); + mmu_sync_children(vcpu, sp, true); + } + } + + write_unlock(&vcpu->kvm->mmu_lock); +} + +void kvm_mmu_sync_prev_roots(struct kvm_vcpu *vcpu) +{ + unsigned long roots_to_free = 0; + int i; + + for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) + if (is_unsync_root(vcpu->arch.mmu->prev_roots[i].hpa)) + roots_to_free |= KVM_MMU_ROOT_PREVIOUS(i); + + /* sync prev_roots by simply freeing them */ + kvm_mmu_free_roots(vcpu->kvm, vcpu->arch.mmu, roots_to_free); +} + +static gpa_t nonpaging_gva_to_gpa(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, + gpa_t vaddr, u64 access, + struct x86_exception *exception) +{ + if (exception) + exception->error_code = 0; + return kvm_translate_gpa(vcpu, mmu, vaddr, access, exception); +} + +static bool mmio_info_in_cache(struct kvm_vcpu *vcpu, u64 addr, bool direct) +{ + /* + * A nested guest cannot use the MMIO cache if it is using nested + * page tables, because cr2 is a nGPA while the cache stores GPAs. + */ + if (mmu_is_nested(vcpu)) + return false; + + if (direct) + return vcpu_match_mmio_gpa(vcpu, addr); + + return vcpu_match_mmio_gva(vcpu, addr); +} + +/* + * Return the level of the lowest level SPTE added to sptes. + * That SPTE may be non-present. + * + * Must be called between walk_shadow_page_lockless_{begin,end}. + */ +static int get_walk(struct kvm_vcpu *vcpu, u64 addr, u64 *sptes, int *root_level) +{ + struct kvm_shadow_walk_iterator iterator; + int leaf = -1; + u64 spte; + + for (shadow_walk_init(&iterator, vcpu, addr), + *root_level = iterator.level; + shadow_walk_okay(&iterator); + __shadow_walk_next(&iterator, spte)) { + leaf = iterator.level; + spte = mmu_spte_get_lockless(iterator.sptep); + + sptes[leaf] = spte; + } + + return leaf; +} + +/* return true if reserved bit(s) are detected on a valid, non-MMIO SPTE. */ +static bool get_mmio_spte(struct kvm_vcpu *vcpu, u64 addr, u64 *sptep) +{ + u64 sptes[PT64_ROOT_MAX_LEVEL + 1]; + struct rsvd_bits_validate *rsvd_check; + int root, leaf, level; + bool reserved = false; + + walk_shadow_page_lockless_begin(vcpu); + + if (is_tdp_mmu(vcpu->arch.mmu)) + leaf = kvm_tdp_mmu_get_walk(vcpu, addr, sptes, &root); + else + leaf = get_walk(vcpu, addr, sptes, &root); + + walk_shadow_page_lockless_end(vcpu); + + if (unlikely(leaf < 0)) { + *sptep = 0ull; + return reserved; + } + + *sptep = sptes[leaf]; + + /* + * Skip reserved bits checks on the terminal leaf if it's not a valid + * SPTE. Note, this also (intentionally) skips MMIO SPTEs, which, by + * design, always have reserved bits set. The purpose of the checks is + * to detect reserved bits on non-MMIO SPTEs. i.e. buggy SPTEs. + */ + if (!is_shadow_present_pte(sptes[leaf])) + leaf++; + + rsvd_check = &vcpu->arch.mmu->shadow_zero_check; + + for (level = root; level >= leaf; level--) + reserved |= is_rsvd_spte(rsvd_check, sptes[level], level); + + if (reserved) { + pr_err("%s: reserved bits set on MMU-present spte, addr 0x%llx, hierarchy:\n", + __func__, addr); + for (level = root; level >= leaf; level--) + pr_err("------ spte = 0x%llx level = %d, rsvd bits = 0x%llx", + sptes[level], level, + get_rsvd_bits(rsvd_check, sptes[level], level)); + } + + return reserved; +} + +static int handle_mmio_page_fault(struct kvm_vcpu *vcpu, u64 addr, bool direct) +{ + u64 spte; + bool reserved; + + if (mmio_info_in_cache(vcpu, addr, direct)) + return RET_PF_EMULATE; + + reserved = get_mmio_spte(vcpu, addr, &spte); + if (WARN_ON(reserved)) + return -EINVAL; + + if (is_mmio_spte(spte)) { + gfn_t gfn = get_mmio_spte_gfn(spte); + unsigned int access = get_mmio_spte_access(spte); + + if (!check_mmio_spte(vcpu, spte)) + return RET_PF_INVALID; + + if (direct) + addr = 0; + + trace_handle_mmio_page_fault(addr, gfn, access); + vcpu_cache_mmio_info(vcpu, addr, gfn, access); + return RET_PF_EMULATE; + } + + /* + * If the page table is zapped by other cpus, let CPU fault again on + * the address. + */ + return RET_PF_RETRY; +} + +static bool page_fault_handle_page_track(struct kvm_vcpu *vcpu, + struct kvm_page_fault *fault) +{ + if (unlikely(fault->rsvd)) + return false; + + if (!fault->present || !fault->write) + return false; + + /* + * guest is writing the page which is write tracked which can + * not be fixed by page fault handler. + */ + if (kvm_slot_page_track_is_active(vcpu->kvm, fault->slot, fault->gfn, KVM_PAGE_TRACK_WRITE)) + return true; + + return false; +} + +static void shadow_page_table_clear_flood(struct kvm_vcpu *vcpu, gva_t addr) +{ + struct kvm_shadow_walk_iterator iterator; + u64 spte; + + walk_shadow_page_lockless_begin(vcpu); + for_each_shadow_entry_lockless(vcpu, addr, iterator, spte) + clear_sp_write_flooding_count(iterator.sptep); + walk_shadow_page_lockless_end(vcpu); +} + +static u32 alloc_apf_token(struct kvm_vcpu *vcpu) +{ + /* make sure the token value is not 0 */ + u32 id = vcpu->arch.apf.id; + + if (id << 12 == 0) + vcpu->arch.apf.id = 1; + + return (vcpu->arch.apf.id++ << 12) | vcpu->vcpu_id; +} + +static bool kvm_arch_setup_async_pf(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, + gfn_t gfn) +{ + struct kvm_arch_async_pf arch; + + arch.token = alloc_apf_token(vcpu); + arch.gfn = gfn; + arch.direct_map = vcpu->arch.mmu->root_role.direct; + arch.cr3 = kvm_mmu_get_guest_pgd(vcpu, vcpu->arch.mmu); + + return kvm_setup_async_pf(vcpu, cr2_or_gpa, + kvm_vcpu_gfn_to_hva(vcpu, gfn), &arch); +} + +void kvm_arch_async_page_ready(struct kvm_vcpu *vcpu, struct kvm_async_pf *work) +{ + int r; + + if ((vcpu->arch.mmu->root_role.direct != work->arch.direct_map) || + work->wakeup_all) + return; + + r = kvm_mmu_reload(vcpu); + if (unlikely(r)) + return; + + if (!vcpu->arch.mmu->root_role.direct && + work->arch.cr3 != kvm_mmu_get_guest_pgd(vcpu, vcpu->arch.mmu)) + return; + + kvm_mmu_do_page_fault(vcpu, work->cr2_or_gpa, 0, true); +} + +static int kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) +{ + struct kvm_memory_slot *slot = fault->slot; + bool async; + + /* + * Retry the page fault if the gfn hit a memslot that is being deleted + * or moved. This ensures any existing SPTEs for the old memslot will + * be zapped before KVM inserts a new MMIO SPTE for the gfn. + */ + if (slot && (slot->flags & KVM_MEMSLOT_INVALID)) + return RET_PF_RETRY; + + if (!kvm_is_visible_memslot(slot)) { + /* Don't expose private memslots to L2. */ + if (is_guest_mode(vcpu)) { + fault->slot = NULL; + fault->pfn = KVM_PFN_NOSLOT; + fault->map_writable = false; + return RET_PF_CONTINUE; + } + /* + * If the APIC access page exists but is disabled, go directly + * to emulation without caching the MMIO access or creating a + * MMIO SPTE. That way the cache doesn't need to be purged + * when the AVIC is re-enabled. + */ + if (slot && slot->id == APIC_ACCESS_PAGE_PRIVATE_MEMSLOT && + !kvm_apicv_activated(vcpu->kvm)) + return RET_PF_EMULATE; + } + + async = false; + fault->pfn = __gfn_to_pfn_memslot(slot, fault->gfn, false, &async, + fault->write, &fault->map_writable, + &fault->hva); + if (!async) + return RET_PF_CONTINUE; /* *pfn has correct page already */ + + if (!fault->prefetch && kvm_can_do_async_pf(vcpu)) { + trace_kvm_try_async_get_page(fault->addr, fault->gfn); + if (kvm_find_async_pf_gfn(vcpu, fault->gfn)) { + trace_kvm_async_pf_repeated_fault(fault->addr, fault->gfn); + kvm_make_request(KVM_REQ_APF_HALT, vcpu); + return RET_PF_RETRY; + } else if (kvm_arch_setup_async_pf(vcpu, fault->addr, fault->gfn)) { + return RET_PF_RETRY; + } + } + + fault->pfn = __gfn_to_pfn_memslot(slot, fault->gfn, false, NULL, + fault->write, &fault->map_writable, + &fault->hva); + return RET_PF_CONTINUE; +} + +/* + * Returns true if the page fault is stale and needs to be retried, i.e. if the + * root was invalidated by a memslot update or a relevant mmu_notifier fired. + */ +static bool is_page_fault_stale(struct kvm_vcpu *vcpu, + struct kvm_page_fault *fault, + unsigned long mmu_seq) +{ + struct kvm_mmu_page *sp = to_shadow_page(vcpu->arch.mmu->root.hpa); + + /* Special roots, e.g. pae_root, are not backed by shadow pages. */ + if (sp && is_obsolete_sp(vcpu->kvm, sp)) + return true; + + /* + * Roots without an associated shadow page are considered invalid if + * there is a pending request to free obsolete roots. The request is + * only a hint that the current root _may_ be obsolete and needs to be + * reloaded, e.g. if the guest frees a PGD that KVM is tracking as a + * previous root, then __kvm_mmu_prepare_zap_page() signals all vCPUs + * to reload even if no vCPU is actively using the root. + */ + if (!sp && kvm_test_request(KVM_REQ_MMU_FREE_OBSOLETE_ROOTS, vcpu)) + return true; + + return fault->slot && + mmu_invalidate_retry_hva(vcpu->kvm, mmu_seq, fault->hva); +} + +static int direct_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) +{ + bool is_tdp_mmu_fault = is_tdp_mmu(vcpu->arch.mmu); + + unsigned long mmu_seq; + int r; + + fault->gfn = fault->addr >> PAGE_SHIFT; + fault->slot = kvm_vcpu_gfn_to_memslot(vcpu, fault->gfn); + + if (page_fault_handle_page_track(vcpu, fault)) + return RET_PF_EMULATE; + + r = fast_page_fault(vcpu, fault); + if (r != RET_PF_INVALID) + return r; + + r = mmu_topup_memory_caches(vcpu, false); + if (r) + return r; + + mmu_seq = vcpu->kvm->mmu_invalidate_seq; + smp_rmb(); + + r = kvm_faultin_pfn(vcpu, fault); + if (r != RET_PF_CONTINUE) + return r; + + r = handle_abnormal_pfn(vcpu, fault, ACC_ALL); + if (r != RET_PF_CONTINUE) + return r; + + r = RET_PF_RETRY; + + if (is_tdp_mmu_fault) + read_lock(&vcpu->kvm->mmu_lock); + else + write_lock(&vcpu->kvm->mmu_lock); + + if (is_page_fault_stale(vcpu, fault, mmu_seq)) + goto out_unlock; + + if (is_tdp_mmu_fault) { + r = kvm_tdp_mmu_map(vcpu, fault); + } else { + r = make_mmu_pages_available(vcpu); + if (r) + goto out_unlock; + r = __direct_map(vcpu, fault); + } + +out_unlock: + if (is_tdp_mmu_fault) + read_unlock(&vcpu->kvm->mmu_lock); + else + write_unlock(&vcpu->kvm->mmu_lock); + kvm_release_pfn_clean(fault->pfn); + return r; +} + +static int nonpaging_page_fault(struct kvm_vcpu *vcpu, + struct kvm_page_fault *fault) +{ + pgprintk("%s: gva %lx error %x\n", __func__, fault->addr, fault->error_code); + + /* This path builds a PAE pagetable, we can map 2mb pages at maximum. */ + fault->max_level = PG_LEVEL_2M; + return direct_page_fault(vcpu, fault); +} + +int kvm_handle_page_fault(struct kvm_vcpu *vcpu, u64 error_code, + u64 fault_address, char *insn, int insn_len) +{ + int r = 1; + u32 flags = vcpu->arch.apf.host_apf_flags; + +#ifndef CONFIG_X86_64 + /* A 64-bit CR2 should be impossible on 32-bit KVM. */ + if (WARN_ON_ONCE(fault_address >> 32)) + return -EFAULT; +#endif + + vcpu->arch.l1tf_flush_l1d = true; + if (!flags) { + trace_kvm_page_fault(vcpu, fault_address, error_code); + + if (kvm_event_needs_reinjection(vcpu)) + kvm_mmu_unprotect_page_virt(vcpu, fault_address); + r = kvm_mmu_page_fault(vcpu, fault_address, error_code, insn, + insn_len); + } else if (flags & KVM_PV_REASON_PAGE_NOT_PRESENT) { + vcpu->arch.apf.host_apf_flags = 0; + local_irq_disable(); + kvm_async_pf_task_wait_schedule(fault_address); + local_irq_enable(); + } else { + WARN_ONCE(1, "Unexpected host async PF flags: %x\n", flags); + } + + return r; +} +EXPORT_SYMBOL_GPL(kvm_handle_page_fault); + +int kvm_tdp_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) +{ + /* + * If the guest's MTRRs may be used to compute the "real" memtype, + * restrict the mapping level to ensure KVM uses a consistent memtype + * across the entire mapping. If the host MTRRs are ignored by TDP + * (shadow_memtype_mask is non-zero), and the VM has non-coherent DMA + * (DMA doesn't snoop CPU caches), KVM's ABI is to honor the memtype + * from the guest's MTRRs so that guest accesses to memory that is + * DMA'd aren't cached against the guest's wishes. + * + * Note, KVM may still ultimately ignore guest MTRRs for certain PFNs, + * e.g. KVM will force UC memtype for host MMIO. + */ + if (shadow_memtype_mask && kvm_arch_has_noncoherent_dma(vcpu->kvm)) { + for ( ; fault->max_level > PG_LEVEL_4K; --fault->max_level) { + int page_num = KVM_PAGES_PER_HPAGE(fault->max_level); + gfn_t base = (fault->addr >> PAGE_SHIFT) & ~(page_num - 1); + + if (kvm_mtrr_check_gfn_range_consistency(vcpu, base, page_num)) + break; + } + } + + return direct_page_fault(vcpu, fault); +} + +static void nonpaging_init_context(struct kvm_mmu *context) +{ + context->page_fault = nonpaging_page_fault; + context->gva_to_gpa = nonpaging_gva_to_gpa; + context->sync_page = nonpaging_sync_page; + context->invlpg = NULL; +} + +static inline bool is_root_usable(struct kvm_mmu_root_info *root, gpa_t pgd, + union kvm_mmu_page_role role) +{ + return (role.direct || pgd == root->pgd) && + VALID_PAGE(root->hpa) && + role.word == to_shadow_page(root->hpa)->role.word; +} + +/* + * Find out if a previously cached root matching the new pgd/role is available, + * and insert the current root as the MRU in the cache. + * If a matching root is found, it is assigned to kvm_mmu->root and + * true is returned. + * If no match is found, kvm_mmu->root is left invalid, the LRU root is + * evicted to make room for the current root, and false is returned. + */ +static bool cached_root_find_and_keep_current(struct kvm *kvm, struct kvm_mmu *mmu, + gpa_t new_pgd, + union kvm_mmu_page_role new_role) +{ + uint i; + + if (is_root_usable(&mmu->root, new_pgd, new_role)) + return true; + + for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) { + /* + * The swaps end up rotating the cache like this: + * C 0 1 2 3 (on entry to the function) + * 0 C 1 2 3 + * 1 C 0 2 3 + * 2 C 0 1 3 + * 3 C 0 1 2 (on exit from the loop) + */ + swap(mmu->root, mmu->prev_roots[i]); + if (is_root_usable(&mmu->root, new_pgd, new_role)) + return true; + } + + kvm_mmu_free_roots(kvm, mmu, KVM_MMU_ROOT_CURRENT); + return false; +} + +/* + * Find out if a previously cached root matching the new pgd/role is available. + * On entry, mmu->root is invalid. + * If a matching root is found, it is assigned to kvm_mmu->root, the LRU entry + * of the cache becomes invalid, and true is returned. + * If no match is found, kvm_mmu->root is left invalid and false is returned. + */ +static bool cached_root_find_without_current(struct kvm *kvm, struct kvm_mmu *mmu, + gpa_t new_pgd, + union kvm_mmu_page_role new_role) +{ + uint i; + + for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) + if (is_root_usable(&mmu->prev_roots[i], new_pgd, new_role)) + goto hit; + + return false; + +hit: + swap(mmu->root, mmu->prev_roots[i]); + /* Bubble up the remaining roots. */ + for (; i < KVM_MMU_NUM_PREV_ROOTS - 1; i++) + mmu->prev_roots[i] = mmu->prev_roots[i + 1]; + mmu->prev_roots[i].hpa = INVALID_PAGE; + return true; +} + +static bool fast_pgd_switch(struct kvm *kvm, struct kvm_mmu *mmu, + gpa_t new_pgd, union kvm_mmu_page_role new_role) +{ + /* + * For now, limit the caching to 64-bit hosts+VMs in order to avoid + * having to deal with PDPTEs. We may add support for 32-bit hosts/VMs + * later if necessary. + */ + if (VALID_PAGE(mmu->root.hpa) && !to_shadow_page(mmu->root.hpa)) + kvm_mmu_free_roots(kvm, mmu, KVM_MMU_ROOT_CURRENT); + + if (VALID_PAGE(mmu->root.hpa)) + return cached_root_find_and_keep_current(kvm, mmu, new_pgd, new_role); + else + return cached_root_find_without_current(kvm, mmu, new_pgd, new_role); +} + +void kvm_mmu_new_pgd(struct kvm_vcpu *vcpu, gpa_t new_pgd) +{ + struct kvm_mmu *mmu = vcpu->arch.mmu; + union kvm_mmu_page_role new_role = mmu->root_role; + + if (!fast_pgd_switch(vcpu->kvm, mmu, new_pgd, new_role)) { + /* kvm_mmu_ensure_valid_pgd will set up a new root. */ + return; + } + + /* + * It's possible that the cached previous root page is obsolete because + * of a change in the MMU generation number. However, changing the + * generation number is accompanied by KVM_REQ_MMU_FREE_OBSOLETE_ROOTS, + * which will free the root set here and allocate a new one. + */ + kvm_make_request(KVM_REQ_LOAD_MMU_PGD, vcpu); + + if (force_flush_and_sync_on_reuse) { + kvm_make_request(KVM_REQ_MMU_SYNC, vcpu); + kvm_make_request(KVM_REQ_TLB_FLUSH_CURRENT, vcpu); + } + + /* + * The last MMIO access's GVA and GPA are cached in the VCPU. When + * switching to a new CR3, that GVA->GPA mapping may no longer be + * valid. So clear any cached MMIO info even when we don't need to sync + * the shadow page tables. + */ + vcpu_clear_mmio_info(vcpu, MMIO_GVA_ANY); + + /* + * If this is a direct root page, it doesn't have a write flooding + * count. Otherwise, clear the write flooding count. + */ + if (!new_role.direct) + __clear_sp_write_flooding_count( + to_shadow_page(vcpu->arch.mmu->root.hpa)); +} +EXPORT_SYMBOL_GPL(kvm_mmu_new_pgd); + +static bool sync_mmio_spte(struct kvm_vcpu *vcpu, u64 *sptep, gfn_t gfn, + unsigned int access) +{ + if (unlikely(is_mmio_spte(*sptep))) { + if (gfn != get_mmio_spte_gfn(*sptep)) { + mmu_spte_clear_no_track(sptep); + return true; + } + + mark_mmio_spte(vcpu, sptep, gfn, access); + return true; + } + + return false; +} + +#define PTTYPE_EPT 18 /* arbitrary */ +#define PTTYPE PTTYPE_EPT +#include "paging_tmpl.h" +#undef PTTYPE + +#define PTTYPE 64 +#include "paging_tmpl.h" +#undef PTTYPE + +#define PTTYPE 32 +#include "paging_tmpl.h" +#undef PTTYPE + +static void +__reset_rsvds_bits_mask(struct rsvd_bits_validate *rsvd_check, + u64 pa_bits_rsvd, int level, bool nx, bool gbpages, + bool pse, bool amd) +{ + u64 gbpages_bit_rsvd = 0; + u64 nonleaf_bit8_rsvd = 0; + u64 high_bits_rsvd; + + rsvd_check->bad_mt_xwr = 0; + + if (!gbpages) + gbpages_bit_rsvd = rsvd_bits(7, 7); + + if (level == PT32E_ROOT_LEVEL) + high_bits_rsvd = pa_bits_rsvd & rsvd_bits(0, 62); + else + high_bits_rsvd = pa_bits_rsvd & rsvd_bits(0, 51); + + /* Note, NX doesn't exist in PDPTEs, this is handled below. */ + if (!nx) + high_bits_rsvd |= rsvd_bits(63, 63); + + /* + * Non-leaf PML4Es and PDPEs reserve bit 8 (which would be the G bit for + * leaf entries) on AMD CPUs only. + */ + if (amd) + nonleaf_bit8_rsvd = rsvd_bits(8, 8); + + switch (level) { + case PT32_ROOT_LEVEL: + /* no rsvd bits for 2 level 4K page table entries */ + rsvd_check->rsvd_bits_mask[0][1] = 0; + rsvd_check->rsvd_bits_mask[0][0] = 0; + rsvd_check->rsvd_bits_mask[1][0] = + rsvd_check->rsvd_bits_mask[0][0]; + + if (!pse) { + rsvd_check->rsvd_bits_mask[1][1] = 0; + break; + } + + if (is_cpuid_PSE36()) + /* 36bits PSE 4MB page */ + rsvd_check->rsvd_bits_mask[1][1] = rsvd_bits(17, 21); + else + /* 32 bits PSE 4MB page */ + rsvd_check->rsvd_bits_mask[1][1] = rsvd_bits(13, 21); + break; + case PT32E_ROOT_LEVEL: + rsvd_check->rsvd_bits_mask[0][2] = rsvd_bits(63, 63) | + high_bits_rsvd | + rsvd_bits(5, 8) | + rsvd_bits(1, 2); /* PDPTE */ + rsvd_check->rsvd_bits_mask[0][1] = high_bits_rsvd; /* PDE */ + rsvd_check->rsvd_bits_mask[0][0] = high_bits_rsvd; /* PTE */ + rsvd_check->rsvd_bits_mask[1][1] = high_bits_rsvd | + rsvd_bits(13, 20); /* large page */ + rsvd_check->rsvd_bits_mask[1][0] = + rsvd_check->rsvd_bits_mask[0][0]; + break; + case PT64_ROOT_5LEVEL: + rsvd_check->rsvd_bits_mask[0][4] = high_bits_rsvd | + nonleaf_bit8_rsvd | + rsvd_bits(7, 7); + rsvd_check->rsvd_bits_mask[1][4] = + rsvd_check->rsvd_bits_mask[0][4]; + fallthrough; + case PT64_ROOT_4LEVEL: + rsvd_check->rsvd_bits_mask[0][3] = high_bits_rsvd | + nonleaf_bit8_rsvd | + rsvd_bits(7, 7); + rsvd_check->rsvd_bits_mask[0][2] = high_bits_rsvd | + gbpages_bit_rsvd; + rsvd_check->rsvd_bits_mask[0][1] = high_bits_rsvd; + rsvd_check->rsvd_bits_mask[0][0] = high_bits_rsvd; + rsvd_check->rsvd_bits_mask[1][3] = + rsvd_check->rsvd_bits_mask[0][3]; + rsvd_check->rsvd_bits_mask[1][2] = high_bits_rsvd | + gbpages_bit_rsvd | + rsvd_bits(13, 29); + rsvd_check->rsvd_bits_mask[1][1] = high_bits_rsvd | + rsvd_bits(13, 20); /* large page */ + rsvd_check->rsvd_bits_mask[1][0] = + rsvd_check->rsvd_bits_mask[0][0]; + break; + } +} + +static bool guest_can_use_gbpages(struct kvm_vcpu *vcpu) +{ + /* + * If TDP is enabled, let the guest use GBPAGES if they're supported in + * hardware. The hardware page walker doesn't let KVM disable GBPAGES, + * i.e. won't treat them as reserved, and KVM doesn't redo the GVA->GPA + * walk for performance and complexity reasons. Not to mention KVM + * _can't_ solve the problem because GVA->GPA walks aren't visible to + * KVM once a TDP translation is installed. Mimic hardware behavior so + * that KVM's is at least consistent, i.e. doesn't randomly inject #PF. + */ + return tdp_enabled ? boot_cpu_has(X86_FEATURE_GBPAGES) : + guest_cpuid_has(vcpu, X86_FEATURE_GBPAGES); +} + +static void reset_guest_rsvds_bits_mask(struct kvm_vcpu *vcpu, + struct kvm_mmu *context) +{ + __reset_rsvds_bits_mask(&context->guest_rsvd_check, + vcpu->arch.reserved_gpa_bits, + context->cpu_role.base.level, is_efer_nx(context), + guest_can_use_gbpages(vcpu), + is_cr4_pse(context), + guest_cpuid_is_amd_or_hygon(vcpu)); +} + +static void +__reset_rsvds_bits_mask_ept(struct rsvd_bits_validate *rsvd_check, + u64 pa_bits_rsvd, bool execonly, int huge_page_level) +{ + u64 high_bits_rsvd = pa_bits_rsvd & rsvd_bits(0, 51); + u64 large_1g_rsvd = 0, large_2m_rsvd = 0; + u64 bad_mt_xwr; + + if (huge_page_level < PG_LEVEL_1G) + large_1g_rsvd = rsvd_bits(7, 7); + if (huge_page_level < PG_LEVEL_2M) + large_2m_rsvd = rsvd_bits(7, 7); + + rsvd_check->rsvd_bits_mask[0][4] = high_bits_rsvd | rsvd_bits(3, 7); + rsvd_check->rsvd_bits_mask[0][3] = high_bits_rsvd | rsvd_bits(3, 7); + rsvd_check->rsvd_bits_mask[0][2] = high_bits_rsvd | rsvd_bits(3, 6) | large_1g_rsvd; + rsvd_check->rsvd_bits_mask[0][1] = high_bits_rsvd | rsvd_bits(3, 6) | large_2m_rsvd; + rsvd_check->rsvd_bits_mask[0][0] = high_bits_rsvd; + + /* large page */ + rsvd_check->rsvd_bits_mask[1][4] = rsvd_check->rsvd_bits_mask[0][4]; + rsvd_check->rsvd_bits_mask[1][3] = rsvd_check->rsvd_bits_mask[0][3]; + rsvd_check->rsvd_bits_mask[1][2] = high_bits_rsvd | rsvd_bits(12, 29) | large_1g_rsvd; + rsvd_check->rsvd_bits_mask[1][1] = high_bits_rsvd | rsvd_bits(12, 20) | large_2m_rsvd; + rsvd_check->rsvd_bits_mask[1][0] = rsvd_check->rsvd_bits_mask[0][0]; + + bad_mt_xwr = 0xFFull << (2 * 8); /* bits 3..5 must not be 2 */ + bad_mt_xwr |= 0xFFull << (3 * 8); /* bits 3..5 must not be 3 */ + bad_mt_xwr |= 0xFFull << (7 * 8); /* bits 3..5 must not be 7 */ + bad_mt_xwr |= REPEAT_BYTE(1ull << 2); /* bits 0..2 must not be 010 */ + bad_mt_xwr |= REPEAT_BYTE(1ull << 6); /* bits 0..2 must not be 110 */ + if (!execonly) { + /* bits 0..2 must not be 100 unless VMX capabilities allow it */ + bad_mt_xwr |= REPEAT_BYTE(1ull << 4); + } + rsvd_check->bad_mt_xwr = bad_mt_xwr; +} + +static void reset_rsvds_bits_mask_ept(struct kvm_vcpu *vcpu, + struct kvm_mmu *context, bool execonly, int huge_page_level) +{ + __reset_rsvds_bits_mask_ept(&context->guest_rsvd_check, + vcpu->arch.reserved_gpa_bits, execonly, + huge_page_level); +} + +static inline u64 reserved_hpa_bits(void) +{ + return rsvd_bits(shadow_phys_bits, 63); +} + +/* + * the page table on host is the shadow page table for the page + * table in guest or amd nested guest, its mmu features completely + * follow the features in guest. + */ +static void reset_shadow_zero_bits_mask(struct kvm_vcpu *vcpu, + struct kvm_mmu *context) +{ + /* @amd adds a check on bit of SPTEs, which KVM shouldn't use anyways. */ + bool is_amd = true; + /* KVM doesn't use 2-level page tables for the shadow MMU. */ + bool is_pse = false; + struct rsvd_bits_validate *shadow_zero_check; + int i; + + WARN_ON_ONCE(context->root_role.level < PT32E_ROOT_LEVEL); + + shadow_zero_check = &context->shadow_zero_check; + __reset_rsvds_bits_mask(shadow_zero_check, reserved_hpa_bits(), + context->root_role.level, + context->root_role.efer_nx, + guest_can_use_gbpages(vcpu), is_pse, is_amd); + + if (!shadow_me_mask) + return; + + for (i = context->root_role.level; --i >= 0;) { + /* + * So far shadow_me_value is a constant during KVM's life + * time. Bits in shadow_me_value are allowed to be set. + * Bits in shadow_me_mask but not in shadow_me_value are + * not allowed to be set. + */ + shadow_zero_check->rsvd_bits_mask[0][i] |= shadow_me_mask; + shadow_zero_check->rsvd_bits_mask[1][i] |= shadow_me_mask; + shadow_zero_check->rsvd_bits_mask[0][i] &= ~shadow_me_value; + shadow_zero_check->rsvd_bits_mask[1][i] &= ~shadow_me_value; + } + +} + +static inline bool boot_cpu_is_amd(void) +{ + WARN_ON_ONCE(!tdp_enabled); + return shadow_x_mask == 0; +} + +/* + * the direct page table on host, use as much mmu features as + * possible, however, kvm currently does not do execution-protection. + */ +static void +reset_tdp_shadow_zero_bits_mask(struct kvm_mmu *context) +{ + struct rsvd_bits_validate *shadow_zero_check; + int i; + + shadow_zero_check = &context->shadow_zero_check; + + if (boot_cpu_is_amd()) + __reset_rsvds_bits_mask(shadow_zero_check, reserved_hpa_bits(), + context->root_role.level, true, + boot_cpu_has(X86_FEATURE_GBPAGES), + false, true); + else + __reset_rsvds_bits_mask_ept(shadow_zero_check, + reserved_hpa_bits(), false, + max_huge_page_level); + + if (!shadow_me_mask) + return; + + for (i = context->root_role.level; --i >= 0;) { + shadow_zero_check->rsvd_bits_mask[0][i] &= ~shadow_me_mask; + shadow_zero_check->rsvd_bits_mask[1][i] &= ~shadow_me_mask; + } +} + +/* + * as the comments in reset_shadow_zero_bits_mask() except it + * is the shadow page table for intel nested guest. + */ +static void +reset_ept_shadow_zero_bits_mask(struct kvm_mmu *context, bool execonly) +{ + __reset_rsvds_bits_mask_ept(&context->shadow_zero_check, + reserved_hpa_bits(), execonly, + max_huge_page_level); +} + +#define BYTE_MASK(access) \ + ((1 & (access) ? 2 : 0) | \ + (2 & (access) ? 4 : 0) | \ + (3 & (access) ? 8 : 0) | \ + (4 & (access) ? 16 : 0) | \ + (5 & (access) ? 32 : 0) | \ + (6 & (access) ? 64 : 0) | \ + (7 & (access) ? 128 : 0)) + + +static void update_permission_bitmask(struct kvm_mmu *mmu, bool ept) +{ + unsigned byte; + + const u8 x = BYTE_MASK(ACC_EXEC_MASK); + const u8 w = BYTE_MASK(ACC_WRITE_MASK); + const u8 u = BYTE_MASK(ACC_USER_MASK); + + bool cr4_smep = is_cr4_smep(mmu); + bool cr4_smap = is_cr4_smap(mmu); + bool cr0_wp = is_cr0_wp(mmu); + bool efer_nx = is_efer_nx(mmu); + + for (byte = 0; byte < ARRAY_SIZE(mmu->permissions); ++byte) { + unsigned pfec = byte << 1; + + /* + * Each "*f" variable has a 1 bit for each UWX value + * that causes a fault with the given PFEC. + */ + + /* Faults from writes to non-writable pages */ + u8 wf = (pfec & PFERR_WRITE_MASK) ? (u8)~w : 0; + /* Faults from user mode accesses to supervisor pages */ + u8 uf = (pfec & PFERR_USER_MASK) ? (u8)~u : 0; + /* Faults from fetches of non-executable pages*/ + u8 ff = (pfec & PFERR_FETCH_MASK) ? (u8)~x : 0; + /* Faults from kernel mode fetches of user pages */ + u8 smepf = 0; + /* Faults from kernel mode accesses of user pages */ + u8 smapf = 0; + + if (!ept) { + /* Faults from kernel mode accesses to user pages */ + u8 kf = (pfec & PFERR_USER_MASK) ? 0 : u; + + /* Not really needed: !nx will cause pte.nx to fault */ + if (!efer_nx) + ff = 0; + + /* Allow supervisor writes if !cr0.wp */ + if (!cr0_wp) + wf = (pfec & PFERR_USER_MASK) ? wf : 0; + + /* Disallow supervisor fetches of user code if cr4.smep */ + if (cr4_smep) + smepf = (pfec & PFERR_FETCH_MASK) ? kf : 0; + + /* + * SMAP:kernel-mode data accesses from user-mode + * mappings should fault. A fault is considered + * as a SMAP violation if all of the following + * conditions are true: + * - X86_CR4_SMAP is set in CR4 + * - A user page is accessed + * - The access is not a fetch + * - The access is supervisor mode + * - If implicit supervisor access or X86_EFLAGS_AC is clear + * + * Here, we cover the first four conditions. + * The fifth is computed dynamically in permission_fault(); + * PFERR_RSVD_MASK bit will be set in PFEC if the access is + * *not* subject to SMAP restrictions. + */ + if (cr4_smap) + smapf = (pfec & (PFERR_RSVD_MASK|PFERR_FETCH_MASK)) ? 0 : kf; + } + + mmu->permissions[byte] = ff | uf | wf | smepf | smapf; + } +} + +/* +* PKU is an additional mechanism by which the paging controls access to +* user-mode addresses based on the value in the PKRU register. Protection +* key violations are reported through a bit in the page fault error code. +* Unlike other bits of the error code, the PK bit is not known at the +* call site of e.g. gva_to_gpa; it must be computed directly in +* permission_fault based on two bits of PKRU, on some machine state (CR4, +* CR0, EFER, CPL), and on other bits of the error code and the page tables. +* +* In particular the following conditions come from the error code, the +* page tables and the machine state: +* - PK is always zero unless CR4.PKE=1 and EFER.LMA=1 +* - PK is always zero if RSVD=1 (reserved bit set) or F=1 (instruction fetch) +* - PK is always zero if U=0 in the page tables +* - PKRU.WD is ignored if CR0.WP=0 and the access is a supervisor access. +* +* The PKRU bitmask caches the result of these four conditions. The error +* code (minus the P bit) and the page table's U bit form an index into the +* PKRU bitmask. Two bits of the PKRU bitmask are then extracted and ANDed +* with the two bits of the PKRU register corresponding to the protection key. +* For the first three conditions above the bits will be 00, thus masking +* away both AD and WD. For all reads or if the last condition holds, WD +* only will be masked away. +*/ +static void update_pkru_bitmask(struct kvm_mmu *mmu) +{ + unsigned bit; + bool wp; + + mmu->pkru_mask = 0; + + if (!is_cr4_pke(mmu)) + return; + + wp = is_cr0_wp(mmu); + + for (bit = 0; bit < ARRAY_SIZE(mmu->permissions); ++bit) { + unsigned pfec, pkey_bits; + bool check_pkey, check_write, ff, uf, wf, pte_user; + + pfec = bit << 1; + ff = pfec & PFERR_FETCH_MASK; + uf = pfec & PFERR_USER_MASK; + wf = pfec & PFERR_WRITE_MASK; + + /* PFEC.RSVD is replaced by ACC_USER_MASK. */ + pte_user = pfec & PFERR_RSVD_MASK; + + /* + * Only need to check the access which is not an + * instruction fetch and is to a user page. + */ + check_pkey = (!ff && pte_user); + /* + * write access is controlled by PKRU if it is a + * user access or CR0.WP = 1. + */ + check_write = check_pkey && wf && (uf || wp); + + /* PKRU.AD stops both read and write access. */ + pkey_bits = !!check_pkey; + /* PKRU.WD stops write access. */ + pkey_bits |= (!!check_write) << 1; + + mmu->pkru_mask |= (pkey_bits & 3) << pfec; + } +} + +static void reset_guest_paging_metadata(struct kvm_vcpu *vcpu, + struct kvm_mmu *mmu) +{ + if (!is_cr0_pg(mmu)) + return; + + reset_guest_rsvds_bits_mask(vcpu, mmu); + update_permission_bitmask(mmu, false); + update_pkru_bitmask(mmu); +} + +static void paging64_init_context(struct kvm_mmu *context) +{ + context->page_fault = paging64_page_fault; + context->gva_to_gpa = paging64_gva_to_gpa; + context->sync_page = paging64_sync_page; + context->invlpg = paging64_invlpg; +} + +static void paging32_init_context(struct kvm_mmu *context) +{ + context->page_fault = paging32_page_fault; + context->gva_to_gpa = paging32_gva_to_gpa; + context->sync_page = paging32_sync_page; + context->invlpg = paging32_invlpg; +} + +static union kvm_cpu_role +kvm_calc_cpu_role(struct kvm_vcpu *vcpu, const struct kvm_mmu_role_regs *regs) +{ + union kvm_cpu_role role = {0}; + + role.base.access = ACC_ALL; + role.base.smm = is_smm(vcpu); + role.base.guest_mode = is_guest_mode(vcpu); + role.ext.valid = 1; + + if (!____is_cr0_pg(regs)) { + role.base.direct = 1; + return role; + } + + role.base.efer_nx = ____is_efer_nx(regs); + role.base.cr0_wp = ____is_cr0_wp(regs); + role.base.smep_andnot_wp = ____is_cr4_smep(regs) && !____is_cr0_wp(regs); + role.base.smap_andnot_wp = ____is_cr4_smap(regs) && !____is_cr0_wp(regs); + role.base.has_4_byte_gpte = !____is_cr4_pae(regs); + + if (____is_efer_lma(regs)) + role.base.level = ____is_cr4_la57(regs) ? PT64_ROOT_5LEVEL + : PT64_ROOT_4LEVEL; + else if (____is_cr4_pae(regs)) + role.base.level = PT32E_ROOT_LEVEL; + else + role.base.level = PT32_ROOT_LEVEL; + + role.ext.cr4_smep = ____is_cr4_smep(regs); + role.ext.cr4_smap = ____is_cr4_smap(regs); + role.ext.cr4_pse = ____is_cr4_pse(regs); + + /* PKEY and LA57 are active iff long mode is active. */ + role.ext.cr4_pke = ____is_efer_lma(regs) && ____is_cr4_pke(regs); + role.ext.cr4_la57 = ____is_efer_lma(regs) && ____is_cr4_la57(regs); + role.ext.efer_lma = ____is_efer_lma(regs); + return role; +} + +void __kvm_mmu_refresh_passthrough_bits(struct kvm_vcpu *vcpu, + struct kvm_mmu *mmu) +{ + const bool cr0_wp = !!kvm_read_cr0_bits(vcpu, X86_CR0_WP); + + BUILD_BUG_ON((KVM_MMU_CR0_ROLE_BITS & KVM_POSSIBLE_CR0_GUEST_BITS) != X86_CR0_WP); + BUILD_BUG_ON((KVM_MMU_CR4_ROLE_BITS & KVM_POSSIBLE_CR4_GUEST_BITS)); + + if (is_cr0_wp(mmu) == cr0_wp) + return; + + mmu->cpu_role.base.cr0_wp = cr0_wp; + reset_guest_paging_metadata(vcpu, mmu); +} + +static inline int kvm_mmu_get_tdp_level(struct kvm_vcpu *vcpu) +{ + /* tdp_root_level is architecture forced level, use it if nonzero */ + if (tdp_root_level) + return tdp_root_level; + + /* Use 5-level TDP if and only if it's useful/necessary. */ + if (max_tdp_level == 5 && cpuid_maxphyaddr(vcpu) <= 48) + return 4; + + return max_tdp_level; +} + +static union kvm_mmu_page_role +kvm_calc_tdp_mmu_root_page_role(struct kvm_vcpu *vcpu, + union kvm_cpu_role cpu_role) +{ + union kvm_mmu_page_role role = {0}; + + role.access = ACC_ALL; + role.cr0_wp = true; + role.efer_nx = true; + role.smm = cpu_role.base.smm; + role.guest_mode = cpu_role.base.guest_mode; + role.ad_disabled = !kvm_ad_enabled(); + role.level = kvm_mmu_get_tdp_level(vcpu); + role.direct = true; + role.has_4_byte_gpte = false; + + return role; +} + +static void init_kvm_tdp_mmu(struct kvm_vcpu *vcpu, + union kvm_cpu_role cpu_role) +{ + struct kvm_mmu *context = &vcpu->arch.root_mmu; + union kvm_mmu_page_role root_role = kvm_calc_tdp_mmu_root_page_role(vcpu, cpu_role); + + if (cpu_role.as_u64 == context->cpu_role.as_u64 && + root_role.word == context->root_role.word) + return; + + context->cpu_role.as_u64 = cpu_role.as_u64; + context->root_role.word = root_role.word; + context->page_fault = kvm_tdp_page_fault; + context->sync_page = nonpaging_sync_page; + context->invlpg = NULL; + context->get_guest_pgd = get_guest_cr3; + context->get_pdptr = kvm_pdptr_read; + context->inject_page_fault = kvm_inject_page_fault; + + if (!is_cr0_pg(context)) + context->gva_to_gpa = nonpaging_gva_to_gpa; + else if (is_cr4_pae(context)) + context->gva_to_gpa = paging64_gva_to_gpa; + else + context->gva_to_gpa = paging32_gva_to_gpa; + + reset_guest_paging_metadata(vcpu, context); + reset_tdp_shadow_zero_bits_mask(context); +} + +static void shadow_mmu_init_context(struct kvm_vcpu *vcpu, struct kvm_mmu *context, + union kvm_cpu_role cpu_role, + union kvm_mmu_page_role root_role) +{ + if (cpu_role.as_u64 == context->cpu_role.as_u64 && + root_role.word == context->root_role.word) + return; + + context->cpu_role.as_u64 = cpu_role.as_u64; + context->root_role.word = root_role.word; + + if (!is_cr0_pg(context)) + nonpaging_init_context(context); + else if (is_cr4_pae(context)) + paging64_init_context(context); + else + paging32_init_context(context); + + reset_guest_paging_metadata(vcpu, context); + reset_shadow_zero_bits_mask(vcpu, context); +} + +static void kvm_init_shadow_mmu(struct kvm_vcpu *vcpu, + union kvm_cpu_role cpu_role) +{ + struct kvm_mmu *context = &vcpu->arch.root_mmu; + union kvm_mmu_page_role root_role; + + root_role = cpu_role.base; + + /* KVM uses PAE paging whenever the guest isn't using 64-bit paging. */ + root_role.level = max_t(u32, root_role.level, PT32E_ROOT_LEVEL); + + /* + * KVM forces EFER.NX=1 when TDP is disabled, reflect it in the MMU role. + * KVM uses NX when TDP is disabled to handle a variety of scenarios, + * notably for huge SPTEs if iTLB multi-hit mitigation is enabled and + * to generate correct permissions for CR0.WP=0/CR4.SMEP=1/EFER.NX=0. + * The iTLB multi-hit workaround can be toggled at any time, so assume + * NX can be used by any non-nested shadow MMU to avoid having to reset + * MMU contexts. + */ + root_role.efer_nx = true; + + shadow_mmu_init_context(vcpu, context, cpu_role, root_role); +} + +void kvm_init_shadow_npt_mmu(struct kvm_vcpu *vcpu, unsigned long cr0, + unsigned long cr4, u64 efer, gpa_t nested_cr3) +{ + struct kvm_mmu *context = &vcpu->arch.guest_mmu; + struct kvm_mmu_role_regs regs = { + .cr0 = cr0, + .cr4 = cr4 & ~X86_CR4_PKE, + .efer = efer, + }; + union kvm_cpu_role cpu_role = kvm_calc_cpu_role(vcpu, ®s); + union kvm_mmu_page_role root_role; + + /* NPT requires CR0.PG=1. */ + WARN_ON_ONCE(cpu_role.base.direct); + + root_role = cpu_role.base; + root_role.level = kvm_mmu_get_tdp_level(vcpu); + if (root_role.level == PT64_ROOT_5LEVEL && + cpu_role.base.level == PT64_ROOT_4LEVEL) + root_role.passthrough = 1; + + shadow_mmu_init_context(vcpu, context, cpu_role, root_role); + kvm_mmu_new_pgd(vcpu, nested_cr3); +} +EXPORT_SYMBOL_GPL(kvm_init_shadow_npt_mmu); + +static union kvm_cpu_role +kvm_calc_shadow_ept_root_page_role(struct kvm_vcpu *vcpu, bool accessed_dirty, + bool execonly, u8 level) +{ + union kvm_cpu_role role = {0}; + + /* + * KVM does not support SMM transfer monitors, and consequently does not + * support the "entry to SMM" control either. role.base.smm is always 0. + */ + WARN_ON_ONCE(is_smm(vcpu)); + role.base.level = level; + role.base.has_4_byte_gpte = false; + role.base.direct = false; + role.base.ad_disabled = !accessed_dirty; + role.base.guest_mode = true; + role.base.access = ACC_ALL; + + role.ext.word = 0; + role.ext.execonly = execonly; + role.ext.valid = 1; + + return role; +} + +void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly, + int huge_page_level, bool accessed_dirty, + gpa_t new_eptp) +{ + struct kvm_mmu *context = &vcpu->arch.guest_mmu; + u8 level = vmx_eptp_page_walk_level(new_eptp); + union kvm_cpu_role new_mode = + kvm_calc_shadow_ept_root_page_role(vcpu, accessed_dirty, + execonly, level); + + if (new_mode.as_u64 != context->cpu_role.as_u64) { + /* EPT, and thus nested EPT, does not consume CR0, CR4, nor EFER. */ + context->cpu_role.as_u64 = new_mode.as_u64; + context->root_role.word = new_mode.base.word; + + context->page_fault = ept_page_fault; + context->gva_to_gpa = ept_gva_to_gpa; + context->sync_page = ept_sync_page; + context->invlpg = ept_invlpg; + + update_permission_bitmask(context, true); + context->pkru_mask = 0; + reset_rsvds_bits_mask_ept(vcpu, context, execonly, huge_page_level); + reset_ept_shadow_zero_bits_mask(context, execonly); + } + + kvm_mmu_new_pgd(vcpu, new_eptp); +} +EXPORT_SYMBOL_GPL(kvm_init_shadow_ept_mmu); + +static void init_kvm_softmmu(struct kvm_vcpu *vcpu, + union kvm_cpu_role cpu_role) +{ + struct kvm_mmu *context = &vcpu->arch.root_mmu; + + kvm_init_shadow_mmu(vcpu, cpu_role); + + context->get_guest_pgd = get_guest_cr3; + context->get_pdptr = kvm_pdptr_read; + context->inject_page_fault = kvm_inject_page_fault; +} + +static void init_kvm_nested_mmu(struct kvm_vcpu *vcpu, + union kvm_cpu_role new_mode) +{ + struct kvm_mmu *g_context = &vcpu->arch.nested_mmu; + + if (new_mode.as_u64 == g_context->cpu_role.as_u64) + return; + + g_context->cpu_role.as_u64 = new_mode.as_u64; + g_context->get_guest_pgd = get_guest_cr3; + g_context->get_pdptr = kvm_pdptr_read; + g_context->inject_page_fault = kvm_inject_page_fault; + + /* + * L2 page tables are never shadowed, so there is no need to sync + * SPTEs. + */ + g_context->invlpg = NULL; + + /* + * Note that arch.mmu->gva_to_gpa translates l2_gpa to l1_gpa using + * L1's nested page tables (e.g. EPT12). The nested translation + * of l2_gva to l1_gpa is done by arch.nested_mmu.gva_to_gpa using + * L2's page tables as the first level of translation and L1's + * nested page tables as the second level of translation. Basically + * the gva_to_gpa functions between mmu and nested_mmu are swapped. + */ + if (!is_paging(vcpu)) + g_context->gva_to_gpa = nonpaging_gva_to_gpa; + else if (is_long_mode(vcpu)) + g_context->gva_to_gpa = paging64_gva_to_gpa; + else if (is_pae(vcpu)) + g_context->gva_to_gpa = paging64_gva_to_gpa; + else + g_context->gva_to_gpa = paging32_gva_to_gpa; + + reset_guest_paging_metadata(vcpu, g_context); +} + +void kvm_init_mmu(struct kvm_vcpu *vcpu) +{ + struct kvm_mmu_role_regs regs = vcpu_to_role_regs(vcpu); + union kvm_cpu_role cpu_role = kvm_calc_cpu_role(vcpu, ®s); + + if (mmu_is_nested(vcpu)) + init_kvm_nested_mmu(vcpu, cpu_role); + else if (tdp_enabled) + init_kvm_tdp_mmu(vcpu, cpu_role); + else + init_kvm_softmmu(vcpu, cpu_role); +} +EXPORT_SYMBOL_GPL(kvm_init_mmu); + +void kvm_mmu_after_set_cpuid(struct kvm_vcpu *vcpu) +{ + /* + * Invalidate all MMU roles to force them to reinitialize as CPUID + * information is factored into reserved bit calculations. + * + * Correctly handling multiple vCPU models with respect to paging and + * physical address properties) in a single VM would require tracking + * all relevant CPUID information in kvm_mmu_page_role. That is very + * undesirable as it would increase the memory requirements for + * gfn_track (see struct kvm_mmu_page_role comments). For now that + * problem is swept under the rug; KVM's CPUID API is horrific and + * it's all but impossible to solve it without introducing a new API. + */ + vcpu->arch.root_mmu.root_role.word = 0; + vcpu->arch.guest_mmu.root_role.word = 0; + vcpu->arch.nested_mmu.root_role.word = 0; + vcpu->arch.root_mmu.cpu_role.ext.valid = 0; + vcpu->arch.guest_mmu.cpu_role.ext.valid = 0; + vcpu->arch.nested_mmu.cpu_role.ext.valid = 0; + kvm_mmu_reset_context(vcpu); + + /* + * Changing guest CPUID after KVM_RUN is forbidden, see the comment in + * kvm_arch_vcpu_ioctl(). + */ + KVM_BUG_ON(vcpu->arch.last_vmentry_cpu != -1, vcpu->kvm); +} + +void kvm_mmu_reset_context(struct kvm_vcpu *vcpu) +{ + kvm_mmu_unload(vcpu); + kvm_init_mmu(vcpu); +} +EXPORT_SYMBOL_GPL(kvm_mmu_reset_context); + +int kvm_mmu_load(struct kvm_vcpu *vcpu) +{ + int r; + + r = mmu_topup_memory_caches(vcpu, !vcpu->arch.mmu->root_role.direct); + if (r) + goto out; + r = mmu_alloc_special_roots(vcpu); + if (r) + goto out; + if (vcpu->arch.mmu->root_role.direct) + r = mmu_alloc_direct_roots(vcpu); + else + r = mmu_alloc_shadow_roots(vcpu); + if (r) + goto out; + + kvm_mmu_sync_roots(vcpu); + + kvm_mmu_load_pgd(vcpu); + + /* + * Flush any TLB entries for the new root, the provenance of the root + * is unknown. Even if KVM ensures there are no stale TLB entries + * for a freed root, in theory another hypervisor could have left + * stale entries. Flushing on alloc also allows KVM to skip the TLB + * flush when freeing a root (see kvm_tdp_mmu_put_root()). + */ + static_call(kvm_x86_flush_tlb_current)(vcpu); +out: + return r; +} + +void kvm_mmu_unload(struct kvm_vcpu *vcpu) +{ + struct kvm *kvm = vcpu->kvm; + + kvm_mmu_free_roots(kvm, &vcpu->arch.root_mmu, KVM_MMU_ROOTS_ALL); + WARN_ON(VALID_PAGE(vcpu->arch.root_mmu.root.hpa)); + kvm_mmu_free_roots(kvm, &vcpu->arch.guest_mmu, KVM_MMU_ROOTS_ALL); + WARN_ON(VALID_PAGE(vcpu->arch.guest_mmu.root.hpa)); + vcpu_clear_mmio_info(vcpu, MMIO_GVA_ANY); +} + +static bool is_obsolete_root(struct kvm *kvm, hpa_t root_hpa) +{ + struct kvm_mmu_page *sp; + + if (!VALID_PAGE(root_hpa)) + return false; + + /* + * When freeing obsolete roots, treat roots as obsolete if they don't + * have an associated shadow page. This does mean KVM will get false + * positives and free roots that don't strictly need to be freed, but + * such false positives are relatively rare: + * + * (a) only PAE paging and nested NPT has roots without shadow pages + * (b) remote reloads due to a memslot update obsoletes _all_ roots + * (c) KVM doesn't track previous roots for PAE paging, and the guest + * is unlikely to zap an in-use PGD. + */ + sp = to_shadow_page(root_hpa); + return !sp || is_obsolete_sp(kvm, sp); +} + +static void __kvm_mmu_free_obsolete_roots(struct kvm *kvm, struct kvm_mmu *mmu) +{ + unsigned long roots_to_free = 0; + int i; + + if (is_obsolete_root(kvm, mmu->root.hpa)) + roots_to_free |= KVM_MMU_ROOT_CURRENT; + + for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) { + if (is_obsolete_root(kvm, mmu->prev_roots[i].hpa)) + roots_to_free |= KVM_MMU_ROOT_PREVIOUS(i); + } + + if (roots_to_free) + kvm_mmu_free_roots(kvm, mmu, roots_to_free); +} + +void kvm_mmu_free_obsolete_roots(struct kvm_vcpu *vcpu) +{ + __kvm_mmu_free_obsolete_roots(vcpu->kvm, &vcpu->arch.root_mmu); + __kvm_mmu_free_obsolete_roots(vcpu->kvm, &vcpu->arch.guest_mmu); +} + +static u64 mmu_pte_write_fetch_gpte(struct kvm_vcpu *vcpu, gpa_t *gpa, + int *bytes) +{ + u64 gentry = 0; + int r; + + /* + * Assume that the pte write on a page table of the same type + * as the current vcpu paging mode since we update the sptes only + * when they have the same mode. + */ + if (is_pae(vcpu) && *bytes == 4) { + /* Handle a 32-bit guest writing two halves of a 64-bit gpte */ + *gpa &= ~(gpa_t)7; + *bytes = 8; + } + + if (*bytes == 4 || *bytes == 8) { + r = kvm_vcpu_read_guest_atomic(vcpu, *gpa, &gentry, *bytes); + if (r) + gentry = 0; + } + + return gentry; +} + +/* + * If we're seeing too many writes to a page, it may no longer be a page table, + * or we may be forking, in which case it is better to unmap the page. + */ +static bool detect_write_flooding(struct kvm_mmu_page *sp) +{ + /* + * Skip write-flooding detected for the sp whose level is 1, because + * it can become unsync, then the guest page is not write-protected. + */ + if (sp->role.level == PG_LEVEL_4K) + return false; + + atomic_inc(&sp->write_flooding_count); + return atomic_read(&sp->write_flooding_count) >= 3; +} + +/* + * Misaligned accesses are too much trouble to fix up; also, they usually + * indicate a page is not used as a page table. + */ +static bool detect_write_misaligned(struct kvm_mmu_page *sp, gpa_t gpa, + int bytes) +{ + unsigned offset, pte_size, misaligned; + + pgprintk("misaligned: gpa %llx bytes %d role %x\n", + gpa, bytes, sp->role.word); + + offset = offset_in_page(gpa); + pte_size = sp->role.has_4_byte_gpte ? 4 : 8; + + /* + * Sometimes, the OS only writes the last one bytes to update status + * bits, for example, in linux, andb instruction is used in clear_bit(). + */ + if (!(offset & (pte_size - 1)) && bytes == 1) + return false; + + misaligned = (offset ^ (offset + bytes - 1)) & ~(pte_size - 1); + misaligned |= bytes < 4; + + return misaligned; +} + +static u64 *get_written_sptes(struct kvm_mmu_page *sp, gpa_t gpa, int *nspte) +{ + unsigned page_offset, quadrant; + u64 *spte; + int level; + + page_offset = offset_in_page(gpa); + level = sp->role.level; + *nspte = 1; + if (sp->role.has_4_byte_gpte) { + page_offset <<= 1; /* 32->64 */ + /* + * A 32-bit pde maps 4MB while the shadow pdes map + * only 2MB. So we need to double the offset again + * and zap two pdes instead of one. + */ + if (level == PT32_ROOT_LEVEL) { + page_offset &= ~7; /* kill rounding error */ + page_offset <<= 1; + *nspte = 2; + } + quadrant = page_offset >> PAGE_SHIFT; + page_offset &= ~PAGE_MASK; + if (quadrant != sp->role.quadrant) + return NULL; + } + + spte = &sp->spt[page_offset / sizeof(*spte)]; + return spte; +} + +static void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa, + const u8 *new, int bytes, + struct kvm_page_track_notifier_node *node) +{ + gfn_t gfn = gpa >> PAGE_SHIFT; + struct kvm_mmu_page *sp; + LIST_HEAD(invalid_list); + u64 entry, gentry, *spte; + int npte; + bool flush = false; + + /* + * If we don't have indirect shadow pages, it means no page is + * write-protected, so we can exit simply. + */ + if (!READ_ONCE(vcpu->kvm->arch.indirect_shadow_pages)) + return; + + pgprintk("%s: gpa %llx bytes %d\n", __func__, gpa, bytes); + + write_lock(&vcpu->kvm->mmu_lock); + + gentry = mmu_pte_write_fetch_gpte(vcpu, &gpa, &bytes); + + ++vcpu->kvm->stat.mmu_pte_write; + + for_each_gfn_valid_sp_with_gptes(vcpu->kvm, sp, gfn) { + if (detect_write_misaligned(sp, gpa, bytes) || + detect_write_flooding(sp)) { + kvm_mmu_prepare_zap_page(vcpu->kvm, sp, &invalid_list); + ++vcpu->kvm->stat.mmu_flooded; + continue; + } + + spte = get_written_sptes(sp, gpa, &npte); + if (!spte) + continue; + + while (npte--) { + entry = *spte; + mmu_page_zap_pte(vcpu->kvm, sp, spte, NULL); + if (gentry && sp->role.level != PG_LEVEL_4K) + ++vcpu->kvm->stat.mmu_pde_zapped; + if (is_shadow_present_pte(entry)) + flush = true; + ++spte; + } + } + kvm_mmu_remote_flush_or_zap(vcpu->kvm, &invalid_list, flush); + write_unlock(&vcpu->kvm->mmu_lock); +} + +int noinline kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 error_code, + void *insn, int insn_len) +{ + int r, emulation_type = EMULTYPE_PF; + bool direct = vcpu->arch.mmu->root_role.direct; + + if (WARN_ON(!VALID_PAGE(vcpu->arch.mmu->root.hpa))) + return RET_PF_RETRY; + + r = RET_PF_INVALID; + if (unlikely(error_code & PFERR_RSVD_MASK)) { + r = handle_mmio_page_fault(vcpu, cr2_or_gpa, direct); + if (r == RET_PF_EMULATE) + goto emulate; + } + + if (r == RET_PF_INVALID) { + r = kvm_mmu_do_page_fault(vcpu, cr2_or_gpa, + lower_32_bits(error_code), false); + if (KVM_BUG_ON(r == RET_PF_INVALID, vcpu->kvm)) + return -EIO; + } + + if (r < 0) + return r; + if (r != RET_PF_EMULATE) + return 1; + + /* + * Before emulating the instruction, check if the error code + * was due to a RO violation while translating the guest page. + * This can occur when using nested virtualization with nested + * paging in both guests. If true, we simply unprotect the page + * and resume the guest. + */ + if (vcpu->arch.mmu->root_role.direct && + (error_code & PFERR_NESTED_GUEST_PAGE) == PFERR_NESTED_GUEST_PAGE) { + kvm_mmu_unprotect_page(vcpu->kvm, gpa_to_gfn(cr2_or_gpa)); + return 1; + } + + /* + * vcpu->arch.mmu.page_fault returned RET_PF_EMULATE, but we can still + * optimistically try to just unprotect the page and let the processor + * re-execute the instruction that caused the page fault. Do not allow + * retrying MMIO emulation, as it's not only pointless but could also + * cause us to enter an infinite loop because the processor will keep + * faulting on the non-existent MMIO address. Retrying an instruction + * from a nested guest is also pointless and dangerous as we are only + * explicitly shadowing L1's page tables, i.e. unprotecting something + * for L1 isn't going to magically fix whatever issue cause L2 to fail. + */ + if (!mmio_info_in_cache(vcpu, cr2_or_gpa, direct) && !is_guest_mode(vcpu)) + emulation_type |= EMULTYPE_ALLOW_RETRY_PF; +emulate: + return x86_emulate_instruction(vcpu, cr2_or_gpa, emulation_type, insn, + insn_len); +} +EXPORT_SYMBOL_GPL(kvm_mmu_page_fault); + +void kvm_mmu_invalidate_gva(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, + gva_t gva, hpa_t root_hpa) +{ + int i; + + /* It's actually a GPA for vcpu->arch.guest_mmu. */ + if (mmu != &vcpu->arch.guest_mmu) { + /* INVLPG on a non-canonical address is a NOP according to the SDM. */ + if (is_noncanonical_address(gva, vcpu)) + return; + + static_call(kvm_x86_flush_tlb_gva)(vcpu, gva); + } + + if (!mmu->invlpg) + return; + + if (root_hpa == INVALID_PAGE) { + mmu->invlpg(vcpu, gva, mmu->root.hpa); + + /* + * INVLPG is required to invalidate any global mappings for the VA, + * irrespective of PCID. Since it would take us roughly similar amount + * of work to determine whether any of the prev_root mappings of the VA + * is marked global, or to just sync it blindly, so we might as well + * just always sync it. + * + * Mappings not reachable via the current cr3 or the prev_roots will be + * synced when switching to that cr3, so nothing needs to be done here + * for them. + */ + for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) + if (VALID_PAGE(mmu->prev_roots[i].hpa)) + mmu->invlpg(vcpu, gva, mmu->prev_roots[i].hpa); + } else { + mmu->invlpg(vcpu, gva, root_hpa); + } +} + +void kvm_mmu_invlpg(struct kvm_vcpu *vcpu, gva_t gva) +{ + kvm_mmu_invalidate_gva(vcpu, vcpu->arch.walk_mmu, gva, INVALID_PAGE); + ++vcpu->stat.invlpg; +} +EXPORT_SYMBOL_GPL(kvm_mmu_invlpg); + + +void kvm_mmu_invpcid_gva(struct kvm_vcpu *vcpu, gva_t gva, unsigned long pcid) +{ + struct kvm_mmu *mmu = vcpu->arch.mmu; + bool tlb_flush = false; + uint i; + + if (pcid == kvm_get_active_pcid(vcpu)) { + if (mmu->invlpg) + mmu->invlpg(vcpu, gva, mmu->root.hpa); + tlb_flush = true; + } + + for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) { + if (VALID_PAGE(mmu->prev_roots[i].hpa) && + pcid == kvm_get_pcid(vcpu, mmu->prev_roots[i].pgd)) { + if (mmu->invlpg) + mmu->invlpg(vcpu, gva, mmu->prev_roots[i].hpa); + tlb_flush = true; + } + } + + if (tlb_flush) + static_call(kvm_x86_flush_tlb_gva)(vcpu, gva); + + ++vcpu->stat.invlpg; + + /* + * Mappings not reachable via the current cr3 or the prev_roots will be + * synced when switching to that cr3, so nothing needs to be done here + * for them. + */ +} + +void kvm_configure_mmu(bool enable_tdp, int tdp_forced_root_level, + int tdp_max_root_level, int tdp_huge_page_level) +{ + tdp_enabled = enable_tdp; + tdp_root_level = tdp_forced_root_level; + max_tdp_level = tdp_max_root_level; + + /* + * max_huge_page_level reflects KVM's MMU capabilities irrespective + * of kernel support, e.g. KVM may be capable of using 1GB pages when + * the kernel is not. But, KVM never creates a page size greater than + * what is used by the kernel for any given HVA, i.e. the kernel's + * capabilities are ultimately consulted by kvm_mmu_hugepage_adjust(). + */ + if (tdp_enabled) + max_huge_page_level = tdp_huge_page_level; + else if (boot_cpu_has(X86_FEATURE_GBPAGES)) + max_huge_page_level = PG_LEVEL_1G; + else + max_huge_page_level = PG_LEVEL_2M; +} +EXPORT_SYMBOL_GPL(kvm_configure_mmu); + +/* The return value indicates if tlb flush on all vcpus is needed. */ +typedef bool (*slot_level_handler) (struct kvm *kvm, + struct kvm_rmap_head *rmap_head, + const struct kvm_memory_slot *slot); + +/* The caller should hold mmu-lock before calling this function. */ +static __always_inline bool +slot_handle_level_range(struct kvm *kvm, const struct kvm_memory_slot *memslot, + slot_level_handler fn, int start_level, int end_level, + gfn_t start_gfn, gfn_t end_gfn, bool flush_on_yield, + bool flush) +{ + struct slot_rmap_walk_iterator iterator; + + for_each_slot_rmap_range(memslot, start_level, end_level, start_gfn, + end_gfn, &iterator) { + if (iterator.rmap) + flush |= fn(kvm, iterator.rmap, memslot); + + if (need_resched() || rwlock_needbreak(&kvm->mmu_lock)) { + if (flush && flush_on_yield) { + kvm_flush_remote_tlbs_with_address(kvm, + start_gfn, + iterator.gfn - start_gfn + 1); + flush = false; + } + cond_resched_rwlock_write(&kvm->mmu_lock); + } + } + + return flush; +} + +static __always_inline bool +slot_handle_level(struct kvm *kvm, const struct kvm_memory_slot *memslot, + slot_level_handler fn, int start_level, int end_level, + bool flush_on_yield) +{ + return slot_handle_level_range(kvm, memslot, fn, start_level, + end_level, memslot->base_gfn, + memslot->base_gfn + memslot->npages - 1, + flush_on_yield, false); +} + +static __always_inline bool +slot_handle_level_4k(struct kvm *kvm, const struct kvm_memory_slot *memslot, + slot_level_handler fn, bool flush_on_yield) +{ + return slot_handle_level(kvm, memslot, fn, PG_LEVEL_4K, + PG_LEVEL_4K, flush_on_yield); +} + +static void free_mmu_pages(struct kvm_mmu *mmu) +{ + if (!tdp_enabled && mmu->pae_root) + set_memory_encrypted((unsigned long)mmu->pae_root, 1); + free_page((unsigned long)mmu->pae_root); + free_page((unsigned long)mmu->pml4_root); + free_page((unsigned long)mmu->pml5_root); +} + +static int __kvm_mmu_create(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu) +{ + struct page *page; + int i; + + mmu->root.hpa = INVALID_PAGE; + mmu->root.pgd = 0; + for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) + mmu->prev_roots[i] = KVM_MMU_ROOT_INFO_INVALID; + + /* vcpu->arch.guest_mmu isn't used when !tdp_enabled. */ + if (!tdp_enabled && mmu == &vcpu->arch.guest_mmu) + return 0; + + /* + * When using PAE paging, the four PDPTEs are treated as 'root' pages, + * while the PDP table is a per-vCPU construct that's allocated at MMU + * creation. When emulating 32-bit mode, cr3 is only 32 bits even on + * x86_64. Therefore we need to allocate the PDP table in the first + * 4GB of memory, which happens to fit the DMA32 zone. TDP paging + * generally doesn't use PAE paging and can skip allocating the PDP + * table. The main exception, handled here, is SVM's 32-bit NPT. The + * other exception is for shadowing L1's 32-bit or PAE NPT on 64-bit + * KVM; that horror is handled on-demand by mmu_alloc_special_roots(). + */ + if (tdp_enabled && kvm_mmu_get_tdp_level(vcpu) > PT32E_ROOT_LEVEL) + return 0; + + page = alloc_page(GFP_KERNEL_ACCOUNT | __GFP_DMA32); + if (!page) + return -ENOMEM; + + mmu->pae_root = page_address(page); + + /* + * CR3 is only 32 bits when PAE paging is used, thus it's impossible to + * get the CPU to treat the PDPTEs as encrypted. Decrypt the page so + * that KVM's writes and the CPU's reads get along. Note, this is + * only necessary when using shadow paging, as 64-bit NPT can get at + * the C-bit even when shadowing 32-bit NPT, and SME isn't supported + * by 32-bit kernels (when KVM itself uses 32-bit NPT). + */ + if (!tdp_enabled) + set_memory_decrypted((unsigned long)mmu->pae_root, 1); + else + WARN_ON_ONCE(shadow_me_value); + + for (i = 0; i < 4; ++i) + mmu->pae_root[i] = INVALID_PAE_ROOT; + + return 0; +} + +int kvm_mmu_create(struct kvm_vcpu *vcpu) +{ + int ret; + + vcpu->arch.mmu_pte_list_desc_cache.kmem_cache = pte_list_desc_cache; + vcpu->arch.mmu_pte_list_desc_cache.gfp_zero = __GFP_ZERO; + + vcpu->arch.mmu_page_header_cache.kmem_cache = mmu_page_header_cache; + vcpu->arch.mmu_page_header_cache.gfp_zero = __GFP_ZERO; + + vcpu->arch.mmu_shadow_page_cache.gfp_zero = __GFP_ZERO; + + vcpu->arch.mmu = &vcpu->arch.root_mmu; + vcpu->arch.walk_mmu = &vcpu->arch.root_mmu; + + ret = __kvm_mmu_create(vcpu, &vcpu->arch.guest_mmu); + if (ret) + return ret; + + ret = __kvm_mmu_create(vcpu, &vcpu->arch.root_mmu); + if (ret) + goto fail_allocate_root; + + return ret; + fail_allocate_root: + free_mmu_pages(&vcpu->arch.guest_mmu); + return ret; +} + +#define BATCH_ZAP_PAGES 10 +static void kvm_zap_obsolete_pages(struct kvm *kvm) +{ + struct kvm_mmu_page *sp, *node; + int nr_zapped, batch = 0; + bool unstable; + +restart: + list_for_each_entry_safe_reverse(sp, node, + &kvm->arch.active_mmu_pages, link) { + /* + * No obsolete valid page exists before a newly created page + * since active_mmu_pages is a FIFO list. + */ + if (!is_obsolete_sp(kvm, sp)) + break; + + /* + * Invalid pages should never land back on the list of active + * pages. Skip the bogus page, otherwise we'll get stuck in an + * infinite loop if the page gets put back on the list (again). + */ + if (WARN_ON(sp->role.invalid)) + continue; + + /* + * No need to flush the TLB since we're only zapping shadow + * pages with an obsolete generation number and all vCPUS have + * loaded a new root, i.e. the shadow pages being zapped cannot + * be in active use by the guest. + */ + if (batch >= BATCH_ZAP_PAGES && + cond_resched_rwlock_write(&kvm->mmu_lock)) { + batch = 0; + goto restart; + } + + unstable = __kvm_mmu_prepare_zap_page(kvm, sp, + &kvm->arch.zapped_obsolete_pages, &nr_zapped); + batch += nr_zapped; + + if (unstable) + goto restart; + } + + /* + * Kick all vCPUs (via remote TLB flush) before freeing the page tables + * to ensure KVM is not in the middle of a lockless shadow page table + * walk, which may reference the pages. The remote TLB flush itself is + * not required and is simply a convenient way to kick vCPUs as needed. + * KVM performs a local TLB flush when allocating a new root (see + * kvm_mmu_load()), and the reload in the caller ensure no vCPUs are + * running with an obsolete MMU. + */ + kvm_mmu_commit_zap_page(kvm, &kvm->arch.zapped_obsolete_pages); +} + +/* + * Fast invalidate all shadow pages and use lock-break technique + * to zap obsolete pages. + * + * It's required when memslot is being deleted or VM is being + * destroyed, in these cases, we should ensure that KVM MMU does + * not use any resource of the being-deleted slot or all slots + * after calling the function. + */ +static void kvm_mmu_zap_all_fast(struct kvm *kvm) +{ + lockdep_assert_held(&kvm->slots_lock); + + write_lock(&kvm->mmu_lock); + trace_kvm_mmu_zap_all_fast(kvm); + + /* + * Toggle mmu_valid_gen between '0' and '1'. Because slots_lock is + * held for the entire duration of zapping obsolete pages, it's + * impossible for there to be multiple invalid generations associated + * with *valid* shadow pages at any given time, i.e. there is exactly + * one valid generation and (at most) one invalid generation. + */ + kvm->arch.mmu_valid_gen = kvm->arch.mmu_valid_gen ? 0 : 1; + + /* + * In order to ensure all vCPUs drop their soon-to-be invalid roots, + * invalidating TDP MMU roots must be done while holding mmu_lock for + * write and in the same critical section as making the reload request, + * e.g. before kvm_zap_obsolete_pages() could drop mmu_lock and yield. + */ + if (is_tdp_mmu_enabled(kvm)) + kvm_tdp_mmu_invalidate_all_roots(kvm); + + /* + * Notify all vcpus to reload its shadow page table and flush TLB. + * Then all vcpus will switch to new shadow page table with the new + * mmu_valid_gen. + * + * Note: we need to do this under the protection of mmu_lock, + * otherwise, vcpu would purge shadow page but miss tlb flush. + */ + kvm_make_all_cpus_request(kvm, KVM_REQ_MMU_FREE_OBSOLETE_ROOTS); + + kvm_zap_obsolete_pages(kvm); + + write_unlock(&kvm->mmu_lock); + + /* + * Zap the invalidated TDP MMU roots, all SPTEs must be dropped before + * returning to the caller, e.g. if the zap is in response to a memslot + * deletion, mmu_notifier callbacks will be unable to reach the SPTEs + * associated with the deleted memslot once the update completes, and + * Deferring the zap until the final reference to the root is put would + * lead to use-after-free. + */ + if (is_tdp_mmu_enabled(kvm)) + kvm_tdp_mmu_zap_invalidated_roots(kvm); +} + +static bool kvm_has_zapped_obsolete_pages(struct kvm *kvm) +{ + return unlikely(!list_empty_careful(&kvm->arch.zapped_obsolete_pages)); +} + +static void kvm_mmu_invalidate_zap_pages_in_memslot(struct kvm *kvm, + struct kvm_memory_slot *slot, + struct kvm_page_track_notifier_node *node) +{ + kvm_mmu_zap_all_fast(kvm); +} + +void kvm_mmu_init_vm(struct kvm *kvm) +{ + struct kvm_page_track_notifier_node *node = &kvm->arch.mmu_sp_tracker; + + INIT_LIST_HEAD(&kvm->arch.active_mmu_pages); + INIT_LIST_HEAD(&kvm->arch.zapped_obsolete_pages); + INIT_LIST_HEAD(&kvm->arch.lpage_disallowed_mmu_pages); + spin_lock_init(&kvm->arch.mmu_unsync_pages_lock); + + kvm_mmu_init_tdp_mmu(kvm); + + node->track_write = kvm_mmu_pte_write; + node->track_flush_slot = kvm_mmu_invalidate_zap_pages_in_memslot; + kvm_page_track_register_notifier(kvm, node); + + kvm->arch.split_page_header_cache.kmem_cache = mmu_page_header_cache; + kvm->arch.split_page_header_cache.gfp_zero = __GFP_ZERO; + + kvm->arch.split_shadow_page_cache.gfp_zero = __GFP_ZERO; + + kvm->arch.split_desc_cache.kmem_cache = pte_list_desc_cache; + kvm->arch.split_desc_cache.gfp_zero = __GFP_ZERO; +} + +static void mmu_free_vm_memory_caches(struct kvm *kvm) +{ + kvm_mmu_free_memory_cache(&kvm->arch.split_desc_cache); + kvm_mmu_free_memory_cache(&kvm->arch.split_page_header_cache); + kvm_mmu_free_memory_cache(&kvm->arch.split_shadow_page_cache); +} + +void kvm_mmu_uninit_vm(struct kvm *kvm) +{ + struct kvm_page_track_notifier_node *node = &kvm->arch.mmu_sp_tracker; + + kvm_page_track_unregister_notifier(kvm, node); + + kvm_mmu_uninit_tdp_mmu(kvm); + + mmu_free_vm_memory_caches(kvm); +} + +static bool kvm_rmap_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end) +{ + const struct kvm_memory_slot *memslot; + struct kvm_memslots *slots; + struct kvm_memslot_iter iter; + bool flush = false; + gfn_t start, end; + int i; + + if (!kvm_memslots_have_rmaps(kvm)) + return flush; + + for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) { + slots = __kvm_memslots(kvm, i); + + kvm_for_each_memslot_in_gfn_range(&iter, slots, gfn_start, gfn_end) { + memslot = iter.slot; + start = max(gfn_start, memslot->base_gfn); + end = min(gfn_end, memslot->base_gfn + memslot->npages); + if (WARN_ON_ONCE(start >= end)) + continue; + + flush = slot_handle_level_range(kvm, memslot, __kvm_zap_rmap, + PG_LEVEL_4K, KVM_MAX_HUGEPAGE_LEVEL, + start, end - 1, true, flush); + } + } + + return flush; +} + +/* + * Invalidate (zap) SPTEs that cover GFNs from gfn_start and up to gfn_end + * (not including it) + */ +void kvm_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end) +{ + bool flush; + + if (WARN_ON_ONCE(gfn_end <= gfn_start)) + return; + + write_lock(&kvm->mmu_lock); + + kvm_mmu_invalidate_begin(kvm, 0, -1ul); + + flush = kvm_rmap_zap_gfn_range(kvm, gfn_start, gfn_end); + + if (is_tdp_mmu_enabled(kvm)) + flush = kvm_tdp_mmu_zap_leafs(kvm, gfn_start, gfn_end, flush); + + if (flush) + kvm_flush_remote_tlbs_with_address(kvm, gfn_start, + gfn_end - gfn_start); + + kvm_mmu_invalidate_end(kvm, 0, -1ul); + + write_unlock(&kvm->mmu_lock); +} + +static bool slot_rmap_write_protect(struct kvm *kvm, + struct kvm_rmap_head *rmap_head, + const struct kvm_memory_slot *slot) +{ + return rmap_write_protect(rmap_head, false); +} + +void kvm_mmu_slot_remove_write_access(struct kvm *kvm, + const struct kvm_memory_slot *memslot, + int start_level) +{ + if (kvm_memslots_have_rmaps(kvm)) { + write_lock(&kvm->mmu_lock); + slot_handle_level(kvm, memslot, slot_rmap_write_protect, + start_level, KVM_MAX_HUGEPAGE_LEVEL, false); + write_unlock(&kvm->mmu_lock); + } + + if (is_tdp_mmu_enabled(kvm)) { + read_lock(&kvm->mmu_lock); + kvm_tdp_mmu_wrprot_slot(kvm, memslot, start_level); + read_unlock(&kvm->mmu_lock); + } +} + +static inline bool need_topup(struct kvm_mmu_memory_cache *cache, int min) +{ + return kvm_mmu_memory_cache_nr_free_objects(cache) < min; +} + +static bool need_topup_split_caches_or_resched(struct kvm *kvm) +{ + if (need_resched() || rwlock_needbreak(&kvm->mmu_lock)) + return true; + + /* + * In the worst case, SPLIT_DESC_CACHE_MIN_NR_OBJECTS descriptors are needed + * to split a single huge page. Calculating how many are actually needed + * is possible but not worth the complexity. + */ + return need_topup(&kvm->arch.split_desc_cache, SPLIT_DESC_CACHE_MIN_NR_OBJECTS) || + need_topup(&kvm->arch.split_page_header_cache, 1) || + need_topup(&kvm->arch.split_shadow_page_cache, 1); +} + +static int topup_split_caches(struct kvm *kvm) +{ + /* + * Allocating rmap list entries when splitting huge pages for nested + * MMUs is uncommon as KVM needs to use a list if and only if there is + * more than one rmap entry for a gfn, i.e. requires an L1 gfn to be + * aliased by multiple L2 gfns and/or from multiple nested roots with + * different roles. Aliasing gfns when using TDP is atypical for VMMs; + * a few gfns are often aliased during boot, e.g. when remapping BIOS, + * but aliasing rarely occurs post-boot or for many gfns. If there is + * only one rmap entry, rmap->val points directly at that one entry and + * doesn't need to allocate a list. Buffer the cache by the default + * capacity so that KVM doesn't have to drop mmu_lock to topup if KVM + * encounters an aliased gfn or two. + */ + const int capacity = SPLIT_DESC_CACHE_MIN_NR_OBJECTS + + KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE; + int r; + + lockdep_assert_held(&kvm->slots_lock); + + r = __kvm_mmu_topup_memory_cache(&kvm->arch.split_desc_cache, capacity, + SPLIT_DESC_CACHE_MIN_NR_OBJECTS); + if (r) + return r; + + r = kvm_mmu_topup_memory_cache(&kvm->arch.split_page_header_cache, 1); + if (r) + return r; + + return kvm_mmu_topup_memory_cache(&kvm->arch.split_shadow_page_cache, 1); +} + +static struct kvm_mmu_page *shadow_mmu_get_sp_for_split(struct kvm *kvm, u64 *huge_sptep) +{ + struct kvm_mmu_page *huge_sp = sptep_to_sp(huge_sptep); + struct shadow_page_caches caches = {}; + union kvm_mmu_page_role role; + unsigned int access; + gfn_t gfn; + + gfn = kvm_mmu_page_get_gfn(huge_sp, spte_index(huge_sptep)); + access = kvm_mmu_page_get_access(huge_sp, spte_index(huge_sptep)); + + /* + * Note, huge page splitting always uses direct shadow pages, regardless + * of whether the huge page itself is mapped by a direct or indirect + * shadow page, since the huge page region itself is being directly + * mapped with smaller pages. + */ + role = kvm_mmu_child_role(huge_sptep, /*direct=*/true, access); + + /* Direct SPs do not require a shadowed_info_cache. */ + caches.page_header_cache = &kvm->arch.split_page_header_cache; + caches.shadow_page_cache = &kvm->arch.split_shadow_page_cache; + + /* Safe to pass NULL for vCPU since requesting a direct SP. */ + return __kvm_mmu_get_shadow_page(kvm, NULL, &caches, gfn, role); +} + +static void shadow_mmu_split_huge_page(struct kvm *kvm, + const struct kvm_memory_slot *slot, + u64 *huge_sptep) + +{ + struct kvm_mmu_memory_cache *cache = &kvm->arch.split_desc_cache; + u64 huge_spte = READ_ONCE(*huge_sptep); + struct kvm_mmu_page *sp; + bool flush = false; + u64 *sptep, spte; + gfn_t gfn; + int index; + + sp = shadow_mmu_get_sp_for_split(kvm, huge_sptep); + + for (index = 0; index < SPTE_ENT_PER_PAGE; index++) { + sptep = &sp->spt[index]; + gfn = kvm_mmu_page_get_gfn(sp, index); + + /* + * The SP may already have populated SPTEs, e.g. if this huge + * page is aliased by multiple sptes with the same access + * permissions. These entries are guaranteed to map the same + * gfn-to-pfn translation since the SP is direct, so no need to + * modify them. + * + * However, if a given SPTE points to a lower level page table, + * that lower level page table may only be partially populated. + * Installing such SPTEs would effectively unmap a potion of the + * huge page. Unmapping guest memory always requires a TLB flush + * since a subsequent operation on the unmapped regions would + * fail to detect the need to flush. + */ + if (is_shadow_present_pte(*sptep)) { + flush |= !is_last_spte(*sptep, sp->role.level); + continue; + } + + spte = make_huge_page_split_spte(kvm, huge_spte, sp->role, index); + mmu_spte_set(sptep, spte); + __rmap_add(kvm, cache, slot, sptep, gfn, sp->role.access); + } + + __link_shadow_page(kvm, cache, huge_sptep, sp, flush); +} + +static int shadow_mmu_try_split_huge_page(struct kvm *kvm, + const struct kvm_memory_slot *slot, + u64 *huge_sptep) +{ + struct kvm_mmu_page *huge_sp = sptep_to_sp(huge_sptep); + int level, r = 0; + gfn_t gfn; + u64 spte; + + /* Grab information for the tracepoint before dropping the MMU lock. */ + gfn = kvm_mmu_page_get_gfn(huge_sp, spte_index(huge_sptep)); + level = huge_sp->role.level; + spte = *huge_sptep; + + if (kvm_mmu_available_pages(kvm) <= KVM_MIN_FREE_MMU_PAGES) { + r = -ENOSPC; + goto out; + } + + if (need_topup_split_caches_or_resched(kvm)) { + write_unlock(&kvm->mmu_lock); + cond_resched(); + /* + * If the topup succeeds, return -EAGAIN to indicate that the + * rmap iterator should be restarted because the MMU lock was + * dropped. + */ + r = topup_split_caches(kvm) ?: -EAGAIN; + write_lock(&kvm->mmu_lock); + goto out; + } + + shadow_mmu_split_huge_page(kvm, slot, huge_sptep); + +out: + trace_kvm_mmu_split_huge_page(gfn, spte, level, r); + return r; +} + +static bool shadow_mmu_try_split_huge_pages(struct kvm *kvm, + struct kvm_rmap_head *rmap_head, + const struct kvm_memory_slot *slot) +{ + struct rmap_iterator iter; + struct kvm_mmu_page *sp; + u64 *huge_sptep; + int r; + +restart: + for_each_rmap_spte(rmap_head, &iter, huge_sptep) { + sp = sptep_to_sp(huge_sptep); + + /* TDP MMU is enabled, so rmap only contains nested MMU SPs. */ + if (WARN_ON_ONCE(!sp->role.guest_mode)) + continue; + + /* The rmaps should never contain non-leaf SPTEs. */ + if (WARN_ON_ONCE(!is_large_pte(*huge_sptep))) + continue; + + /* SPs with level >PG_LEVEL_4K should never by unsync. */ + if (WARN_ON_ONCE(sp->unsync)) + continue; + + /* Don't bother splitting huge pages on invalid SPs. */ + if (sp->role.invalid) + continue; + + r = shadow_mmu_try_split_huge_page(kvm, slot, huge_sptep); + + /* + * The split succeeded or needs to be retried because the MMU + * lock was dropped. Either way, restart the iterator to get it + * back into a consistent state. + */ + if (!r || r == -EAGAIN) + goto restart; + + /* The split failed and shouldn't be retried (e.g. -ENOMEM). */ + break; + } + + return false; +} + +static void kvm_shadow_mmu_try_split_huge_pages(struct kvm *kvm, + const struct kvm_memory_slot *slot, + gfn_t start, gfn_t end, + int target_level) +{ + int level; + + /* + * Split huge pages starting with KVM_MAX_HUGEPAGE_LEVEL and working + * down to the target level. This ensures pages are recursively split + * all the way to the target level. There's no need to split pages + * already at the target level. + */ + for (level = KVM_MAX_HUGEPAGE_LEVEL; level > target_level; level--) { + slot_handle_level_range(kvm, slot, shadow_mmu_try_split_huge_pages, + level, level, start, end - 1, true, false); + } +} + +/* Must be called with the mmu_lock held in write-mode. */ +void kvm_mmu_try_split_huge_pages(struct kvm *kvm, + const struct kvm_memory_slot *memslot, + u64 start, u64 end, + int target_level) +{ + if (!is_tdp_mmu_enabled(kvm)) + return; + + if (kvm_memslots_have_rmaps(kvm)) + kvm_shadow_mmu_try_split_huge_pages(kvm, memslot, start, end, target_level); + + kvm_tdp_mmu_try_split_huge_pages(kvm, memslot, start, end, target_level, false); + + /* + * A TLB flush is unnecessary at this point for the same resons as in + * kvm_mmu_slot_try_split_huge_pages(). + */ +} + +void kvm_mmu_slot_try_split_huge_pages(struct kvm *kvm, + const struct kvm_memory_slot *memslot, + int target_level) +{ + u64 start = memslot->base_gfn; + u64 end = start + memslot->npages; + + if (!is_tdp_mmu_enabled(kvm)) + return; + + if (kvm_memslots_have_rmaps(kvm)) { + write_lock(&kvm->mmu_lock); + kvm_shadow_mmu_try_split_huge_pages(kvm, memslot, start, end, target_level); + write_unlock(&kvm->mmu_lock); + } + + read_lock(&kvm->mmu_lock); + kvm_tdp_mmu_try_split_huge_pages(kvm, memslot, start, end, target_level, true); + read_unlock(&kvm->mmu_lock); + + /* + * No TLB flush is necessary here. KVM will flush TLBs after + * write-protecting and/or clearing dirty on the newly split SPTEs to + * ensure that guest writes are reflected in the dirty log before the + * ioctl to enable dirty logging on this memslot completes. Since the + * split SPTEs retain the write and dirty bits of the huge SPTE, it is + * safe for KVM to decide if a TLB flush is necessary based on the split + * SPTEs. + */ +} + +static bool kvm_mmu_zap_collapsible_spte(struct kvm *kvm, + struct kvm_rmap_head *rmap_head, + const struct kvm_memory_slot *slot) +{ + u64 *sptep; + struct rmap_iterator iter; + int need_tlb_flush = 0; + struct kvm_mmu_page *sp; + +restart: + for_each_rmap_spte(rmap_head, &iter, sptep) { + sp = sptep_to_sp(sptep); + + /* + * We cannot do huge page mapping for indirect shadow pages, + * which are found on the last rmap (level = 1) when not using + * tdp; such shadow pages are synced with the page table in + * the guest, and the guest page table is using 4K page size + * mapping if the indirect sp has level = 1. + */ + if (sp->role.direct && + sp->role.level < kvm_mmu_max_mapping_level(kvm, slot, sp->gfn, + PG_LEVEL_NUM)) { + kvm_zap_one_rmap_spte(kvm, rmap_head, sptep); + + if (kvm_available_flush_tlb_with_range()) + kvm_flush_remote_tlbs_with_address(kvm, sp->gfn, + KVM_PAGES_PER_HPAGE(sp->role.level)); + else + need_tlb_flush = 1; + + goto restart; + } + } + + return need_tlb_flush; +} + +static void kvm_rmap_zap_collapsible_sptes(struct kvm *kvm, + const struct kvm_memory_slot *slot) +{ + /* + * Note, use KVM_MAX_HUGEPAGE_LEVEL - 1 since there's no need to zap + * pages that are already mapped at the maximum hugepage level. + */ + if (slot_handle_level(kvm, slot, kvm_mmu_zap_collapsible_spte, + PG_LEVEL_4K, KVM_MAX_HUGEPAGE_LEVEL - 1, true)) + kvm_arch_flush_remote_tlbs_memslot(kvm, slot); +} + +void kvm_mmu_zap_collapsible_sptes(struct kvm *kvm, + const struct kvm_memory_slot *slot) +{ + if (kvm_memslots_have_rmaps(kvm)) { + write_lock(&kvm->mmu_lock); + kvm_rmap_zap_collapsible_sptes(kvm, slot); + write_unlock(&kvm->mmu_lock); + } + + if (is_tdp_mmu_enabled(kvm)) { + read_lock(&kvm->mmu_lock); + kvm_tdp_mmu_zap_collapsible_sptes(kvm, slot); + read_unlock(&kvm->mmu_lock); + } +} + +void kvm_arch_flush_remote_tlbs_memslot(struct kvm *kvm, + const struct kvm_memory_slot *memslot) +{ + /* + * All current use cases for flushing the TLBs for a specific memslot + * related to dirty logging, and many do the TLB flush out of mmu_lock. + * The interaction between the various operations on memslot must be + * serialized by slots_locks to ensure the TLB flush from one operation + * is observed by any other operation on the same memslot. + */ + lockdep_assert_held(&kvm->slots_lock); + kvm_flush_remote_tlbs_with_address(kvm, memslot->base_gfn, + memslot->npages); +} + +void kvm_mmu_slot_leaf_clear_dirty(struct kvm *kvm, + const struct kvm_memory_slot *memslot) +{ + if (kvm_memslots_have_rmaps(kvm)) { + write_lock(&kvm->mmu_lock); + /* + * Clear dirty bits only on 4k SPTEs since the legacy MMU only + * support dirty logging at a 4k granularity. + */ + slot_handle_level_4k(kvm, memslot, __rmap_clear_dirty, false); + write_unlock(&kvm->mmu_lock); + } + + if (is_tdp_mmu_enabled(kvm)) { + read_lock(&kvm->mmu_lock); + kvm_tdp_mmu_clear_dirty_slot(kvm, memslot); + read_unlock(&kvm->mmu_lock); + } + + /* + * The caller will flush the TLBs after this function returns. + * + * It's also safe to flush TLBs out of mmu lock here as currently this + * function is only used for dirty logging, in which case flushing TLB + * out of mmu lock also guarantees no dirty pages will be lost in + * dirty_bitmap. + */ +} + +void kvm_mmu_zap_all(struct kvm *kvm) +{ + struct kvm_mmu_page *sp, *node; + LIST_HEAD(invalid_list); + int ign; + + write_lock(&kvm->mmu_lock); +restart: + list_for_each_entry_safe(sp, node, &kvm->arch.active_mmu_pages, link) { + if (WARN_ON(sp->role.invalid)) + continue; + if (__kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list, &ign)) + goto restart; + if (cond_resched_rwlock_write(&kvm->mmu_lock)) + goto restart; + } + + kvm_mmu_commit_zap_page(kvm, &invalid_list); + + if (is_tdp_mmu_enabled(kvm)) + kvm_tdp_mmu_zap_all(kvm); + + write_unlock(&kvm->mmu_lock); +} + +void kvm_mmu_invalidate_mmio_sptes(struct kvm *kvm, u64 gen) +{ + WARN_ON(gen & KVM_MEMSLOT_GEN_UPDATE_IN_PROGRESS); + + gen &= MMIO_SPTE_GEN_MASK; + + /* + * Generation numbers are incremented in multiples of the number of + * address spaces in order to provide unique generations across all + * address spaces. Strip what is effectively the address space + * modifier prior to checking for a wrap of the MMIO generation so + * that a wrap in any address space is detected. + */ + gen &= ~((u64)KVM_ADDRESS_SPACE_NUM - 1); + + /* + * The very rare case: if the MMIO generation number has wrapped, + * zap all shadow pages. + */ + if (unlikely(gen == 0)) { + kvm_debug_ratelimited("kvm: zapping shadow pages for mmio generation wraparound\n"); + kvm_mmu_zap_all_fast(kvm); + } +} + +static unsigned long +mmu_shrink_scan(struct shrinker *shrink, struct shrink_control *sc) +{ + struct kvm *kvm; + int nr_to_scan = sc->nr_to_scan; + unsigned long freed = 0; + + mutex_lock(&kvm_lock); + + list_for_each_entry(kvm, &vm_list, vm_list) { + int idx; + LIST_HEAD(invalid_list); + + /* + * Never scan more than sc->nr_to_scan VM instances. + * Will not hit this condition practically since we do not try + * to shrink more than one VM and it is very unlikely to see + * !n_used_mmu_pages so many times. + */ + if (!nr_to_scan--) + break; + /* + * n_used_mmu_pages is accessed without holding kvm->mmu_lock + * here. We may skip a VM instance errorneosly, but we do not + * want to shrink a VM that only started to populate its MMU + * anyway. + */ + if (!kvm->arch.n_used_mmu_pages && + !kvm_has_zapped_obsolete_pages(kvm)) + continue; + + idx = srcu_read_lock(&kvm->srcu); + write_lock(&kvm->mmu_lock); + + if (kvm_has_zapped_obsolete_pages(kvm)) { + kvm_mmu_commit_zap_page(kvm, + &kvm->arch.zapped_obsolete_pages); + goto unlock; + } + + freed = kvm_mmu_zap_oldest_mmu_pages(kvm, sc->nr_to_scan); + +unlock: + write_unlock(&kvm->mmu_lock); + srcu_read_unlock(&kvm->srcu, idx); + + /* + * unfair on small ones + * per-vm shrinkers cry out + * sadness comes quickly + */ + list_move_tail(&kvm->vm_list, &vm_list); + break; + } + + mutex_unlock(&kvm_lock); + return freed; +} + +static unsigned long +mmu_shrink_count(struct shrinker *shrink, struct shrink_control *sc) +{ + return percpu_counter_read_positive(&kvm_total_used_mmu_pages); +} + +static struct shrinker mmu_shrinker = { + .count_objects = mmu_shrink_count, + .scan_objects = mmu_shrink_scan, + .seeks = DEFAULT_SEEKS * 10, +}; + +static void mmu_destroy_caches(void) +{ + kmem_cache_destroy(pte_list_desc_cache); + kmem_cache_destroy(mmu_page_header_cache); +} + +static int get_nx_huge_pages(char *buffer, const struct kernel_param *kp) +{ + if (nx_hugepage_mitigation_hard_disabled) + return sprintf(buffer, "never\n"); + + return param_get_bool(buffer, kp); +} + +static bool get_nx_auto_mode(void) +{ + /* Return true when CPU has the bug, and mitigations are ON */ + return boot_cpu_has_bug(X86_BUG_ITLB_MULTIHIT) && !cpu_mitigations_off(); +} + +static void __set_nx_huge_pages(bool val) +{ + nx_huge_pages = itlb_multihit_kvm_mitigation = val; +} + +static int set_nx_huge_pages(const char *val, const struct kernel_param *kp) +{ + bool old_val = nx_huge_pages; + bool new_val; + + if (nx_hugepage_mitigation_hard_disabled) + return -EPERM; + + /* In "auto" mode deploy workaround only if CPU has the bug. */ + if (sysfs_streq(val, "off")) { + new_val = 0; + } else if (sysfs_streq(val, "force")) { + new_val = 1; + } else if (sysfs_streq(val, "auto")) { + new_val = get_nx_auto_mode(); + } else if (sysfs_streq(val, "never")) { + new_val = 0; + + mutex_lock(&kvm_lock); + if (!list_empty(&vm_list)) { + mutex_unlock(&kvm_lock); + return -EBUSY; + } + nx_hugepage_mitigation_hard_disabled = true; + mutex_unlock(&kvm_lock); + } else if (kstrtobool(val, &new_val) < 0) { + return -EINVAL; + } + + __set_nx_huge_pages(new_val); + + if (new_val != old_val) { + struct kvm *kvm; + + mutex_lock(&kvm_lock); + + list_for_each_entry(kvm, &vm_list, vm_list) { + mutex_lock(&kvm->slots_lock); + kvm_mmu_zap_all_fast(kvm); + mutex_unlock(&kvm->slots_lock); + + wake_up_process(kvm->arch.nx_lpage_recovery_thread); + } + mutex_unlock(&kvm_lock); + } + + return 0; +} + +/* + * nx_huge_pages needs to be resolved to true/false when kvm.ko is loaded, as + * its default value of -1 is technically undefined behavior for a boolean. + * Forward the module init call to SPTE code so that it too can handle module + * params that need to be resolved/snapshot. + */ +void __init kvm_mmu_x86_module_init(void) +{ + if (nx_huge_pages == -1) + __set_nx_huge_pages(get_nx_auto_mode()); + + kvm_mmu_spte_module_init(); +} + +/* + * The bulk of the MMU initialization is deferred until the vendor module is + * loaded as many of the masks/values may be modified by VMX or SVM, i.e. need + * to be reset when a potentially different vendor module is loaded. + */ +int kvm_mmu_vendor_module_init(void) +{ + int ret = -ENOMEM; + + /* + * MMU roles use union aliasing which is, generally speaking, an + * undefined behavior. However, we supposedly know how compilers behave + * and the current status quo is unlikely to change. Guardians below are + * supposed to let us know if the assumption becomes false. + */ + BUILD_BUG_ON(sizeof(union kvm_mmu_page_role) != sizeof(u32)); + BUILD_BUG_ON(sizeof(union kvm_mmu_extended_role) != sizeof(u32)); + BUILD_BUG_ON(sizeof(union kvm_cpu_role) != sizeof(u64)); + + kvm_mmu_reset_all_pte_masks(); + + pte_list_desc_cache = kmem_cache_create("pte_list_desc", + sizeof(struct pte_list_desc), + 0, SLAB_ACCOUNT, NULL); + if (!pte_list_desc_cache) + goto out; + + mmu_page_header_cache = kmem_cache_create("kvm_mmu_page_header", + sizeof(struct kvm_mmu_page), + 0, SLAB_ACCOUNT, NULL); + if (!mmu_page_header_cache) + goto out; + + if (percpu_counter_init(&kvm_total_used_mmu_pages, 0, GFP_KERNEL)) + goto out; + + ret = register_shrinker(&mmu_shrinker, "x86-mmu"); + if (ret) + goto out_shrinker; + + return 0; + +out_shrinker: + percpu_counter_destroy(&kvm_total_used_mmu_pages); +out: + mmu_destroy_caches(); + return ret; +} + +void kvm_mmu_destroy(struct kvm_vcpu *vcpu) +{ + kvm_mmu_unload(vcpu); + free_mmu_pages(&vcpu->arch.root_mmu); + free_mmu_pages(&vcpu->arch.guest_mmu); + mmu_free_memory_caches(vcpu); +} + +void kvm_mmu_vendor_module_exit(void) +{ + mmu_destroy_caches(); + percpu_counter_destroy(&kvm_total_used_mmu_pages); + unregister_shrinker(&mmu_shrinker); +} + +/* + * Calculate the effective recovery period, accounting for '0' meaning "let KVM + * select a halving time of 1 hour". Returns true if recovery is enabled. + */ +static bool calc_nx_huge_pages_recovery_period(uint *period) +{ + /* + * Use READ_ONCE to get the params, this may be called outside of the + * param setters, e.g. by the kthread to compute its next timeout. + */ + bool enabled = READ_ONCE(nx_huge_pages); + uint ratio = READ_ONCE(nx_huge_pages_recovery_ratio); + + if (!enabled || !ratio) + return false; + + *period = READ_ONCE(nx_huge_pages_recovery_period_ms); + if (!*period) { + /* Make sure the period is not less than one second. */ + ratio = min(ratio, 3600u); + *period = 60 * 60 * 1000 / ratio; + } + return true; +} + +static int set_nx_huge_pages_recovery_param(const char *val, const struct kernel_param *kp) +{ + bool was_recovery_enabled, is_recovery_enabled; + uint old_period, new_period; + int err; + + if (nx_hugepage_mitigation_hard_disabled) + return -EPERM; + + was_recovery_enabled = calc_nx_huge_pages_recovery_period(&old_period); + + err = param_set_uint(val, kp); + if (err) + return err; + + is_recovery_enabled = calc_nx_huge_pages_recovery_period(&new_period); + + if (is_recovery_enabled && + (!was_recovery_enabled || old_period > new_period)) { + struct kvm *kvm; + + mutex_lock(&kvm_lock); + + list_for_each_entry(kvm, &vm_list, vm_list) + wake_up_process(kvm->arch.nx_lpage_recovery_thread); + + mutex_unlock(&kvm_lock); + } + + return err; +} + +static void kvm_recover_nx_lpages(struct kvm *kvm) +{ + unsigned long nx_lpage_splits = kvm->stat.nx_lpage_splits; + int rcu_idx; + struct kvm_mmu_page *sp; + unsigned int ratio; + LIST_HEAD(invalid_list); + bool flush = false; + ulong to_zap; + + rcu_idx = srcu_read_lock(&kvm->srcu); + write_lock(&kvm->mmu_lock); + + /* + * Zapping TDP MMU shadow pages, including the remote TLB flush, must + * be done under RCU protection, because the pages are freed via RCU + * callback. + */ + rcu_read_lock(); + + ratio = READ_ONCE(nx_huge_pages_recovery_ratio); + to_zap = ratio ? DIV_ROUND_UP(nx_lpage_splits, ratio) : 0; + for ( ; to_zap; --to_zap) { + if (list_empty(&kvm->arch.lpage_disallowed_mmu_pages)) + break; + + /* + * We use a separate list instead of just using active_mmu_pages + * because the number of lpage_disallowed pages is expected to + * be relatively small compared to the total. + */ + sp = list_first_entry(&kvm->arch.lpage_disallowed_mmu_pages, + struct kvm_mmu_page, + lpage_disallowed_link); + WARN_ON_ONCE(!sp->lpage_disallowed); + if (is_tdp_mmu_page(sp)) { + flush |= kvm_tdp_mmu_zap_sp(kvm, sp); + } else { + kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list); + WARN_ON_ONCE(sp->lpage_disallowed); + } + + if (need_resched() || rwlock_needbreak(&kvm->mmu_lock)) { + kvm_mmu_remote_flush_or_zap(kvm, &invalid_list, flush); + rcu_read_unlock(); + + cond_resched_rwlock_write(&kvm->mmu_lock); + flush = false; + + rcu_read_lock(); + } + } + kvm_mmu_remote_flush_or_zap(kvm, &invalid_list, flush); + + rcu_read_unlock(); + + write_unlock(&kvm->mmu_lock); + srcu_read_unlock(&kvm->srcu, rcu_idx); +} + +static long get_nx_lpage_recovery_timeout(u64 start_time) +{ + bool enabled; + uint period; + + enabled = calc_nx_huge_pages_recovery_period(&period); + + return enabled ? start_time + msecs_to_jiffies(period) - get_jiffies_64() + : MAX_SCHEDULE_TIMEOUT; +} + +static int kvm_nx_lpage_recovery_worker(struct kvm *kvm, uintptr_t data) +{ + u64 start_time; + long remaining_time; + + while (true) { + start_time = get_jiffies_64(); + remaining_time = get_nx_lpage_recovery_timeout(start_time); + + set_current_state(TASK_INTERRUPTIBLE); + while (!kthread_should_stop() && remaining_time > 0) { + schedule_timeout(remaining_time); + remaining_time = get_nx_lpage_recovery_timeout(start_time); + set_current_state(TASK_INTERRUPTIBLE); + } + + set_current_state(TASK_RUNNING); + + if (kthread_should_stop()) + return 0; + + kvm_recover_nx_lpages(kvm); + } +} + +int kvm_mmu_post_init_vm(struct kvm *kvm) +{ + int err; + + if (nx_hugepage_mitigation_hard_disabled) + return 0; + + err = kvm_vm_create_worker_thread(kvm, kvm_nx_lpage_recovery_worker, 0, + "kvm-nx-lpage-recovery", + &kvm->arch.nx_lpage_recovery_thread); + if (!err) + kthread_unpark(kvm->arch.nx_lpage_recovery_thread); + + return err; +} + +void kvm_mmu_pre_destroy_vm(struct kvm *kvm) +{ + if (kvm->arch.nx_lpage_recovery_thread) + kthread_stop(kvm->arch.nx_lpage_recovery_thread); +} diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h new file mode 100644 index 000000000..0a9d5f292 --- /dev/null +++ b/arch/x86/kvm/mmu/mmu_internal.h @@ -0,0 +1,320 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __KVM_X86_MMU_INTERNAL_H +#define __KVM_X86_MMU_INTERNAL_H + +#include <linux/types.h> +#include <linux/kvm_host.h> +#include <asm/kvm_host.h> + +#undef MMU_DEBUG + +#ifdef MMU_DEBUG +extern bool dbg; + +#define pgprintk(x...) do { if (dbg) printk(x); } while (0) +#define rmap_printk(fmt, args...) do { if (dbg) printk("%s: " fmt, __func__, ## args); } while (0) +#define MMU_WARN_ON(x) WARN_ON(x) +#else +#define pgprintk(x...) do { } while (0) +#define rmap_printk(x...) do { } while (0) +#define MMU_WARN_ON(x) do { } while (0) +#endif + +/* Page table builder macros common to shadow (host) PTEs and guest PTEs. */ +#define __PT_LEVEL_SHIFT(level, bits_per_level) \ + (PAGE_SHIFT + ((level) - 1) * (bits_per_level)) +#define __PT_INDEX(address, level, bits_per_level) \ + (((address) >> __PT_LEVEL_SHIFT(level, bits_per_level)) & ((1 << (bits_per_level)) - 1)) + +#define __PT_LVL_ADDR_MASK(base_addr_mask, level, bits_per_level) \ + ((base_addr_mask) & ~((1ULL << (PAGE_SHIFT + (((level) - 1) * (bits_per_level)))) - 1)) + +#define __PT_LVL_OFFSET_MASK(base_addr_mask, level, bits_per_level) \ + ((base_addr_mask) & ((1ULL << (PAGE_SHIFT + (((level) - 1) * (bits_per_level)))) - 1)) + +#define __PT_ENT_PER_PAGE(bits_per_level) (1 << (bits_per_level)) + +/* + * Unlike regular MMU roots, PAE "roots", a.k.a. PDPTEs/PDPTRs, have a PRESENT + * bit, and thus are guaranteed to be non-zero when valid. And, when a guest + * PDPTR is !PRESENT, its corresponding PAE root cannot be set to INVALID_PAGE, + * as the CPU would treat that as PRESENT PDPTR with reserved bits set. Use + * '0' instead of INVALID_PAGE to indicate an invalid PAE root. + */ +#define INVALID_PAE_ROOT 0 +#define IS_VALID_PAE_ROOT(x) (!!(x)) + +typedef u64 __rcu *tdp_ptep_t; + +struct kvm_mmu_page { + /* + * Note, "link" through "spt" fit in a single 64 byte cache line on + * 64-bit kernels, keep it that way unless there's a reason not to. + */ + struct list_head link; + struct hlist_node hash_link; + + bool tdp_mmu_page; + bool unsync; + union { + u8 mmu_valid_gen; + + /* Only accessed under slots_lock. */ + bool tdp_mmu_scheduled_root_to_zap; + }; + bool lpage_disallowed; /* Can't be replaced by an equiv large page */ + + /* + * The following two entries are used to key the shadow page in the + * hash table. + */ + union kvm_mmu_page_role role; + gfn_t gfn; + + u64 *spt; + + /* + * Stores the result of the guest translation being shadowed by each + * SPTE. KVM shadows two types of guest translations: nGPA -> GPA + * (shadow EPT/NPT) and GVA -> GPA (traditional shadow paging). In both + * cases the result of the translation is a GPA and a set of access + * constraints. + * + * The GFN is stored in the upper bits (PAGE_SHIFT) and the shadowed + * access permissions are stored in the lower bits. Note, for + * convenience and uniformity across guests, the access permissions are + * stored in KVM format (e.g. ACC_EXEC_MASK) not the raw guest format. + */ + u64 *shadowed_translation; + + /* Currently serving as active root */ + union { + int root_count; + refcount_t tdp_mmu_root_count; + }; + unsigned int unsync_children; + union { + struct kvm_rmap_head parent_ptes; /* rmap pointers to parent sptes */ + tdp_ptep_t ptep; + }; + DECLARE_BITMAP(unsync_child_bitmap, 512); + + struct list_head lpage_disallowed_link; +#ifdef CONFIG_X86_32 + /* + * Used out of the mmu-lock to avoid reading spte values while an + * update is in progress; see the comments in __get_spte_lockless(). + */ + int clear_spte_count; +#endif + + /* Number of writes since the last time traversal visited this page. */ + atomic_t write_flooding_count; + +#ifdef CONFIG_X86_64 + /* Used for freeing the page asynchronously if it is a TDP MMU page. */ + struct rcu_head rcu_head; +#endif +}; + +extern struct kmem_cache *mmu_page_header_cache; + +static inline struct kvm_mmu_page *to_shadow_page(hpa_t shadow_page) +{ + struct page *page = pfn_to_page(shadow_page >> PAGE_SHIFT); + + return (struct kvm_mmu_page *)page_private(page); +} + +static inline struct kvm_mmu_page *sptep_to_sp(u64 *sptep) +{ + return to_shadow_page(__pa(sptep)); +} + +static inline int kvm_mmu_role_as_id(union kvm_mmu_page_role role) +{ + return role.smm ? 1 : 0; +} + +static inline int kvm_mmu_page_as_id(struct kvm_mmu_page *sp) +{ + return kvm_mmu_role_as_id(sp->role); +} + +static inline bool kvm_mmu_page_ad_need_write_protect(struct kvm_mmu_page *sp) +{ + /* + * When using the EPT page-modification log, the GPAs in the CPU dirty + * log would come from L2 rather than L1. Therefore, we need to rely + * on write protection to record dirty pages, which bypasses PML, since + * writes now result in a vmexit. Note, the check on CPU dirty logging + * being enabled is mandatory as the bits used to denote WP-only SPTEs + * are reserved for PAE paging (32-bit KVM). + */ + return kvm_x86_ops.cpu_dirty_log_size && sp->role.guest_mode; +} + +int mmu_try_to_unsync_pages(struct kvm *kvm, const struct kvm_memory_slot *slot, + gfn_t gfn, bool can_unsync, bool prefetch); + +void kvm_mmu_gfn_disallow_lpage(const struct kvm_memory_slot *slot, gfn_t gfn); +void kvm_mmu_gfn_allow_lpage(const struct kvm_memory_slot *slot, gfn_t gfn); +bool kvm_mmu_slot_gfn_write_protect(struct kvm *kvm, + struct kvm_memory_slot *slot, u64 gfn, + int min_level); +void kvm_flush_remote_tlbs_with_address(struct kvm *kvm, + u64 start_gfn, u64 pages); +unsigned int pte_list_count(struct kvm_rmap_head *rmap_head); + +extern int nx_huge_pages; +static inline bool is_nx_huge_page_enabled(struct kvm *kvm) +{ + return READ_ONCE(nx_huge_pages) && !kvm->arch.disable_nx_huge_pages; +} + +struct kvm_page_fault { + /* arguments to kvm_mmu_do_page_fault. */ + const gpa_t addr; + const u32 error_code; + const bool prefetch; + + /* Derived from error_code. */ + const bool exec; + const bool write; + const bool present; + const bool rsvd; + const bool user; + + /* Derived from mmu and global state. */ + const bool is_tdp; + const bool nx_huge_page_workaround_enabled; + + /* + * Whether a >4KB mapping can be created or is forbidden due to NX + * hugepages. + */ + bool huge_page_disallowed; + + /* + * Maximum page size that can be created for this fault; input to + * FNAME(fetch), __direct_map and kvm_tdp_mmu_map. + */ + u8 max_level; + + /* + * Page size that can be created based on the max_level and the + * page size used by the host mapping. + */ + u8 req_level; + + /* + * Page size that will be created based on the req_level and + * huge_page_disallowed. + */ + u8 goal_level; + + /* Shifted addr, or result of guest page table walk if addr is a gva. */ + gfn_t gfn; + + /* The memslot containing gfn. May be NULL. */ + struct kvm_memory_slot *slot; + + /* Outputs of kvm_faultin_pfn. */ + kvm_pfn_t pfn; + hva_t hva; + bool map_writable; +}; + +int kvm_tdp_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault); + +/* + * Return values of handle_mmio_page_fault(), mmu.page_fault(), fast_page_fault(), + * and of course kvm_mmu_do_page_fault(). + * + * RET_PF_CONTINUE: So far, so good, keep handling the page fault. + * RET_PF_RETRY: let CPU fault again on the address. + * RET_PF_EMULATE: mmio page fault, emulate the instruction directly. + * RET_PF_INVALID: the spte is invalid, let the real page fault path update it. + * RET_PF_FIXED: The faulting entry has been fixed. + * RET_PF_SPURIOUS: The faulting entry was already fixed, e.g. by another vCPU. + * + * Any names added to this enum should be exported to userspace for use in + * tracepoints via TRACE_DEFINE_ENUM() in mmutrace.h + * + * Note, all values must be greater than or equal to zero so as not to encroach + * on -errno return values. Somewhat arbitrarily use '0' for CONTINUE, which + * will allow for efficient machine code when checking for CONTINUE, e.g. + * "TEST %rax, %rax, JNZ", as all "stop!" values are non-zero. + */ +enum { + RET_PF_CONTINUE = 0, + RET_PF_RETRY, + RET_PF_EMULATE, + RET_PF_INVALID, + RET_PF_FIXED, + RET_PF_SPURIOUS, +}; + +static inline int kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, + u32 err, bool prefetch) +{ + struct kvm_page_fault fault = { + .addr = cr2_or_gpa, + .error_code = err, + .exec = err & PFERR_FETCH_MASK, + .write = err & PFERR_WRITE_MASK, + .present = err & PFERR_PRESENT_MASK, + .rsvd = err & PFERR_RSVD_MASK, + .user = err & PFERR_USER_MASK, + .prefetch = prefetch, + .is_tdp = likely(vcpu->arch.mmu->page_fault == kvm_tdp_page_fault), + .nx_huge_page_workaround_enabled = + is_nx_huge_page_enabled(vcpu->kvm), + + .max_level = KVM_MAX_HUGEPAGE_LEVEL, + .req_level = PG_LEVEL_4K, + .goal_level = PG_LEVEL_4K, + }; + int r; + + /* + * Async #PF "faults", a.k.a. prefetch faults, are not faults from the + * guest perspective and have already been counted at the time of the + * original fault. + */ + if (!prefetch) + vcpu->stat.pf_taken++; + + if (IS_ENABLED(CONFIG_RETPOLINE) && fault.is_tdp) + r = kvm_tdp_page_fault(vcpu, &fault); + else + r = vcpu->arch.mmu->page_fault(vcpu, &fault); + + /* + * Similar to above, prefetch faults aren't truly spurious, and the + * async #PF path doesn't do emulation. Do count faults that are fixed + * by the async #PF handler though, otherwise they'll never be counted. + */ + if (r == RET_PF_FIXED) + vcpu->stat.pf_fixed++; + else if (prefetch) + ; + else if (r == RET_PF_EMULATE) + vcpu->stat.pf_emulate++; + else if (r == RET_PF_SPURIOUS) + vcpu->stat.pf_spurious++; + return r; +} + +int kvm_mmu_max_mapping_level(struct kvm *kvm, + const struct kvm_memory_slot *slot, gfn_t gfn, + int max_level); +void kvm_mmu_hugepage_adjust(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault); +void disallowed_hugepage_adjust(struct kvm_page_fault *fault, u64 spte, int cur_level); + +void *mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc); + +void account_huge_nx_page(struct kvm *kvm, struct kvm_mmu_page *sp); +void unaccount_huge_nx_page(struct kvm *kvm, struct kvm_mmu_page *sp); + +#endif /* __KVM_X86_MMU_INTERNAL_H */ diff --git a/arch/x86/kvm/mmu/mmutrace.h b/arch/x86/kvm/mmu/mmutrace.h new file mode 100644 index 000000000..ae86820ce --- /dev/null +++ b/arch/x86/kvm/mmu/mmutrace.h @@ -0,0 +1,451 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#if !defined(_TRACE_KVMMMU_H) || defined(TRACE_HEADER_MULTI_READ) +#define _TRACE_KVMMMU_H + +#include <linux/tracepoint.h> +#include <linux/trace_events.h> + +#undef TRACE_SYSTEM +#define TRACE_SYSTEM kvmmmu + +#define KVM_MMU_PAGE_FIELDS \ + __field(__u8, mmu_valid_gen) \ + __field(__u64, gfn) \ + __field(__u32, role) \ + __field(__u32, root_count) \ + __field(bool, unsync) + +#define KVM_MMU_PAGE_ASSIGN(sp) \ + __entry->mmu_valid_gen = sp->mmu_valid_gen; \ + __entry->gfn = sp->gfn; \ + __entry->role = sp->role.word; \ + __entry->root_count = sp->root_count; \ + __entry->unsync = sp->unsync; + +#define KVM_MMU_PAGE_PRINTK() ({ \ + const char *saved_ptr = trace_seq_buffer_ptr(p); \ + static const char *access_str[] = { \ + "---", "--x", "w--", "w-x", "-u-", "-ux", "wu-", "wux" \ + }; \ + union kvm_mmu_page_role role; \ + \ + role.word = __entry->role; \ + \ + trace_seq_printf(p, "sp gen %u gfn %llx l%u %u-byte q%u%s %s%s" \ + " %snxe %sad root %u %s%c", \ + __entry->mmu_valid_gen, \ + __entry->gfn, role.level, \ + role.has_4_byte_gpte ? 4 : 8, \ + role.quadrant, \ + role.direct ? " direct" : "", \ + access_str[role.access], \ + role.invalid ? " invalid" : "", \ + role.efer_nx ? "" : "!", \ + role.ad_disabled ? "!" : "", \ + __entry->root_count, \ + __entry->unsync ? "unsync" : "sync", 0); \ + saved_ptr; \ + }) + +#define kvm_mmu_trace_pferr_flags \ + { PFERR_PRESENT_MASK, "P" }, \ + { PFERR_WRITE_MASK, "W" }, \ + { PFERR_USER_MASK, "U" }, \ + { PFERR_RSVD_MASK, "RSVD" }, \ + { PFERR_FETCH_MASK, "F" } + +TRACE_DEFINE_ENUM(RET_PF_CONTINUE); +TRACE_DEFINE_ENUM(RET_PF_RETRY); +TRACE_DEFINE_ENUM(RET_PF_EMULATE); +TRACE_DEFINE_ENUM(RET_PF_INVALID); +TRACE_DEFINE_ENUM(RET_PF_FIXED); +TRACE_DEFINE_ENUM(RET_PF_SPURIOUS); + +/* + * A pagetable walk has started + */ +TRACE_EVENT( + kvm_mmu_pagetable_walk, + TP_PROTO(u64 addr, u32 pferr), + TP_ARGS(addr, pferr), + + TP_STRUCT__entry( + __field(__u64, addr) + __field(__u32, pferr) + ), + + TP_fast_assign( + __entry->addr = addr; + __entry->pferr = pferr; + ), + + TP_printk("addr %llx pferr %x %s", __entry->addr, __entry->pferr, + __print_flags(__entry->pferr, "|", kvm_mmu_trace_pferr_flags)) +); + + +/* We just walked a paging element */ +TRACE_EVENT( + kvm_mmu_paging_element, + TP_PROTO(u64 pte, int level), + TP_ARGS(pte, level), + + TP_STRUCT__entry( + __field(__u64, pte) + __field(__u32, level) + ), + + TP_fast_assign( + __entry->pte = pte; + __entry->level = level; + ), + + TP_printk("pte %llx level %u", __entry->pte, __entry->level) +); + +DECLARE_EVENT_CLASS(kvm_mmu_set_bit_class, + + TP_PROTO(unsigned long table_gfn, unsigned index, unsigned size), + + TP_ARGS(table_gfn, index, size), + + TP_STRUCT__entry( + __field(__u64, gpa) + ), + + TP_fast_assign( + __entry->gpa = ((u64)table_gfn << PAGE_SHIFT) + + index * size; + ), + + TP_printk("gpa %llx", __entry->gpa) +); + +/* We set a pte accessed bit */ +DEFINE_EVENT(kvm_mmu_set_bit_class, kvm_mmu_set_accessed_bit, + + TP_PROTO(unsigned long table_gfn, unsigned index, unsigned size), + + TP_ARGS(table_gfn, index, size) +); + +/* We set a pte dirty bit */ +DEFINE_EVENT(kvm_mmu_set_bit_class, kvm_mmu_set_dirty_bit, + + TP_PROTO(unsigned long table_gfn, unsigned index, unsigned size), + + TP_ARGS(table_gfn, index, size) +); + +TRACE_EVENT( + kvm_mmu_walker_error, + TP_PROTO(u32 pferr), + TP_ARGS(pferr), + + TP_STRUCT__entry( + __field(__u32, pferr) + ), + + TP_fast_assign( + __entry->pferr = pferr; + ), + + TP_printk("pferr %x %s", __entry->pferr, + __print_flags(__entry->pferr, "|", kvm_mmu_trace_pferr_flags)) +); + +TRACE_EVENT( + kvm_mmu_get_page, + TP_PROTO(struct kvm_mmu_page *sp, bool created), + TP_ARGS(sp, created), + + TP_STRUCT__entry( + KVM_MMU_PAGE_FIELDS + __field(bool, created) + ), + + TP_fast_assign( + KVM_MMU_PAGE_ASSIGN(sp) + __entry->created = created; + ), + + TP_printk("%s %s", KVM_MMU_PAGE_PRINTK(), + __entry->created ? "new" : "existing") +); + +DECLARE_EVENT_CLASS(kvm_mmu_page_class, + + TP_PROTO(struct kvm_mmu_page *sp), + TP_ARGS(sp), + + TP_STRUCT__entry( + KVM_MMU_PAGE_FIELDS + ), + + TP_fast_assign( + KVM_MMU_PAGE_ASSIGN(sp) + ), + + TP_printk("%s", KVM_MMU_PAGE_PRINTK()) +); + +DEFINE_EVENT(kvm_mmu_page_class, kvm_mmu_sync_page, + TP_PROTO(struct kvm_mmu_page *sp), + + TP_ARGS(sp) +); + +DEFINE_EVENT(kvm_mmu_page_class, kvm_mmu_unsync_page, + TP_PROTO(struct kvm_mmu_page *sp), + + TP_ARGS(sp) +); + +DEFINE_EVENT(kvm_mmu_page_class, kvm_mmu_prepare_zap_page, + TP_PROTO(struct kvm_mmu_page *sp), + + TP_ARGS(sp) +); + +TRACE_EVENT( + mark_mmio_spte, + TP_PROTO(u64 *sptep, gfn_t gfn, u64 spte), + TP_ARGS(sptep, gfn, spte), + + TP_STRUCT__entry( + __field(void *, sptep) + __field(gfn_t, gfn) + __field(unsigned, access) + __field(unsigned int, gen) + ), + + TP_fast_assign( + __entry->sptep = sptep; + __entry->gfn = gfn; + __entry->access = spte & ACC_ALL; + __entry->gen = get_mmio_spte_generation(spte); + ), + + TP_printk("sptep:%p gfn %llx access %x gen %x", __entry->sptep, + __entry->gfn, __entry->access, __entry->gen) +); + +TRACE_EVENT( + handle_mmio_page_fault, + TP_PROTO(u64 addr, gfn_t gfn, unsigned access), + TP_ARGS(addr, gfn, access), + + TP_STRUCT__entry( + __field(u64, addr) + __field(gfn_t, gfn) + __field(unsigned, access) + ), + + TP_fast_assign( + __entry->addr = addr; + __entry->gfn = gfn; + __entry->access = access; + ), + + TP_printk("addr:%llx gfn %llx access %x", __entry->addr, __entry->gfn, + __entry->access) +); + +TRACE_EVENT( + fast_page_fault, + TP_PROTO(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault, + u64 *sptep, u64 old_spte, int ret), + TP_ARGS(vcpu, fault, sptep, old_spte, ret), + + TP_STRUCT__entry( + __field(int, vcpu_id) + __field(gpa_t, cr2_or_gpa) + __field(u32, error_code) + __field(u64 *, sptep) + __field(u64, old_spte) + __field(u64, new_spte) + __field(int, ret) + ), + + TP_fast_assign( + __entry->vcpu_id = vcpu->vcpu_id; + __entry->cr2_or_gpa = fault->addr; + __entry->error_code = fault->error_code; + __entry->sptep = sptep; + __entry->old_spte = old_spte; + __entry->new_spte = *sptep; + __entry->ret = ret; + ), + + TP_printk("vcpu %d gva %llx error_code %s sptep %p old %#llx" + " new %llx spurious %d fixed %d", __entry->vcpu_id, + __entry->cr2_or_gpa, __print_flags(__entry->error_code, "|", + kvm_mmu_trace_pferr_flags), __entry->sptep, + __entry->old_spte, __entry->new_spte, + __entry->ret == RET_PF_SPURIOUS, __entry->ret == RET_PF_FIXED + ) +); + +TRACE_EVENT( + kvm_mmu_zap_all_fast, + TP_PROTO(struct kvm *kvm), + TP_ARGS(kvm), + + TP_STRUCT__entry( + __field(__u8, mmu_valid_gen) + __field(unsigned int, mmu_used_pages) + ), + + TP_fast_assign( + __entry->mmu_valid_gen = kvm->arch.mmu_valid_gen; + __entry->mmu_used_pages = kvm->arch.n_used_mmu_pages; + ), + + TP_printk("kvm-mmu-valid-gen %u used_pages %x", + __entry->mmu_valid_gen, __entry->mmu_used_pages + ) +); + + +TRACE_EVENT( + check_mmio_spte, + TP_PROTO(u64 spte, unsigned int kvm_gen, unsigned int spte_gen), + TP_ARGS(spte, kvm_gen, spte_gen), + + TP_STRUCT__entry( + __field(unsigned int, kvm_gen) + __field(unsigned int, spte_gen) + __field(u64, spte) + ), + + TP_fast_assign( + __entry->kvm_gen = kvm_gen; + __entry->spte_gen = spte_gen; + __entry->spte = spte; + ), + + TP_printk("spte %llx kvm_gen %x spte-gen %x valid %d", __entry->spte, + __entry->kvm_gen, __entry->spte_gen, + __entry->kvm_gen == __entry->spte_gen + ) +); + +TRACE_EVENT( + kvm_mmu_set_spte, + TP_PROTO(int level, gfn_t gfn, u64 *sptep), + TP_ARGS(level, gfn, sptep), + + TP_STRUCT__entry( + __field(u64, gfn) + __field(u64, spte) + __field(u64, sptep) + __field(u8, level) + /* These depend on page entry type, so compute them now. */ + __field(bool, r) + __field(bool, x) + __field(signed char, u) + ), + + TP_fast_assign( + __entry->gfn = gfn; + __entry->spte = *sptep; + __entry->sptep = virt_to_phys(sptep); + __entry->level = level; + __entry->r = shadow_present_mask || (__entry->spte & PT_PRESENT_MASK); + __entry->x = is_executable_pte(__entry->spte); + __entry->u = shadow_user_mask ? !!(__entry->spte & shadow_user_mask) : -1; + ), + + TP_printk("gfn %llx spte %llx (%s%s%s%s) level %d at %llx", + __entry->gfn, __entry->spte, + __entry->r ? "r" : "-", + __entry->spte & PT_WRITABLE_MASK ? "w" : "-", + __entry->x ? "x" : "-", + __entry->u == -1 ? "" : (__entry->u ? "u" : "-"), + __entry->level, __entry->sptep + ) +); + +TRACE_EVENT( + kvm_mmu_spte_requested, + TP_PROTO(struct kvm_page_fault *fault), + TP_ARGS(fault), + + TP_STRUCT__entry( + __field(u64, gfn) + __field(u64, pfn) + __field(u8, level) + ), + + TP_fast_assign( + __entry->gfn = fault->gfn; + __entry->pfn = fault->pfn | (fault->gfn & (KVM_PAGES_PER_HPAGE(fault->goal_level) - 1)); + __entry->level = fault->goal_level; + ), + + TP_printk("gfn %llx pfn %llx level %d", + __entry->gfn, __entry->pfn, __entry->level + ) +); + +TRACE_EVENT( + kvm_tdp_mmu_spte_changed, + TP_PROTO(int as_id, gfn_t gfn, int level, u64 old_spte, u64 new_spte), + TP_ARGS(as_id, gfn, level, old_spte, new_spte), + + TP_STRUCT__entry( + __field(u64, gfn) + __field(u64, old_spte) + __field(u64, new_spte) + /* Level cannot be larger than 5 on x86, so it fits in a u8. */ + __field(u8, level) + /* as_id can only be 0 or 1 x86, so it fits in a u8. */ + __field(u8, as_id) + ), + + TP_fast_assign( + __entry->gfn = gfn; + __entry->old_spte = old_spte; + __entry->new_spte = new_spte; + __entry->level = level; + __entry->as_id = as_id; + ), + + TP_printk("as id %d gfn %llx level %d old_spte %llx new_spte %llx", + __entry->as_id, __entry->gfn, __entry->level, + __entry->old_spte, __entry->new_spte + ) +); + +TRACE_EVENT( + kvm_mmu_split_huge_page, + TP_PROTO(u64 gfn, u64 spte, int level, int errno), + TP_ARGS(gfn, spte, level, errno), + + TP_STRUCT__entry( + __field(u64, gfn) + __field(u64, spte) + __field(int, level) + __field(int, errno) + ), + + TP_fast_assign( + __entry->gfn = gfn; + __entry->spte = spte; + __entry->level = level; + __entry->errno = errno; + ), + + TP_printk("gfn %llx spte %llx level %d errno %d", + __entry->gfn, __entry->spte, __entry->level, __entry->errno) +); + +#endif /* _TRACE_KVMMMU_H */ + +#undef TRACE_INCLUDE_PATH +#define TRACE_INCLUDE_PATH mmu +#undef TRACE_INCLUDE_FILE +#define TRACE_INCLUDE_FILE mmutrace + +/* This part must be outside protection */ +#include <trace/define_trace.h> diff --git a/arch/x86/kvm/mmu/page_track.c b/arch/x86/kvm/mmu/page_track.c new file mode 100644 index 000000000..2e09d1b62 --- /dev/null +++ b/arch/x86/kvm/mmu/page_track.c @@ -0,0 +1,302 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Support KVM gust page tracking + * + * This feature allows us to track page access in guest. Currently, only + * write access is tracked. + * + * Copyright(C) 2015 Intel Corporation. + * + * Author: + * Xiao Guangrong <guangrong.xiao@linux.intel.com> + */ + +#include <linux/kvm_host.h> +#include <linux/rculist.h> + +#include <asm/kvm_page_track.h> + +#include "mmu.h" +#include "mmu_internal.h" + +bool kvm_page_track_write_tracking_enabled(struct kvm *kvm) +{ + return IS_ENABLED(CONFIG_KVM_EXTERNAL_WRITE_TRACKING) || + !tdp_enabled || kvm_shadow_root_allocated(kvm); +} + +void kvm_page_track_free_memslot(struct kvm_memory_slot *slot) +{ + int i; + + for (i = 0; i < KVM_PAGE_TRACK_MAX; i++) { + kvfree(slot->arch.gfn_track[i]); + slot->arch.gfn_track[i] = NULL; + } +} + +int kvm_page_track_create_memslot(struct kvm *kvm, + struct kvm_memory_slot *slot, + unsigned long npages) +{ + int i; + + for (i = 0; i < KVM_PAGE_TRACK_MAX; i++) { + if (i == KVM_PAGE_TRACK_WRITE && + !kvm_page_track_write_tracking_enabled(kvm)) + continue; + + slot->arch.gfn_track[i] = + __vcalloc(npages, sizeof(*slot->arch.gfn_track[i]), + GFP_KERNEL_ACCOUNT); + if (!slot->arch.gfn_track[i]) + goto track_free; + } + + return 0; + +track_free: + kvm_page_track_free_memslot(slot); + return -ENOMEM; +} + +static inline bool page_track_mode_is_valid(enum kvm_page_track_mode mode) +{ + if (mode < 0 || mode >= KVM_PAGE_TRACK_MAX) + return false; + + return true; +} + +int kvm_page_track_write_tracking_alloc(struct kvm_memory_slot *slot) +{ + unsigned short *gfn_track; + + if (slot->arch.gfn_track[KVM_PAGE_TRACK_WRITE]) + return 0; + + gfn_track = __vcalloc(slot->npages, sizeof(*gfn_track), + GFP_KERNEL_ACCOUNT); + if (gfn_track == NULL) + return -ENOMEM; + + slot->arch.gfn_track[KVM_PAGE_TRACK_WRITE] = gfn_track; + return 0; +} + +static void update_gfn_track(struct kvm_memory_slot *slot, gfn_t gfn, + enum kvm_page_track_mode mode, short count) +{ + int index, val; + + index = gfn_to_index(gfn, slot->base_gfn, PG_LEVEL_4K); + + val = slot->arch.gfn_track[mode][index]; + + if (WARN_ON(val + count < 0 || val + count > USHRT_MAX)) + return; + + slot->arch.gfn_track[mode][index] += count; +} + +/* + * add guest page to the tracking pool so that corresponding access on that + * page will be intercepted. + * + * It should be called under the protection both of mmu-lock and kvm->srcu + * or kvm->slots_lock. + * + * @kvm: the guest instance we are interested in. + * @slot: the @gfn belongs to. + * @gfn: the guest page. + * @mode: tracking mode, currently only write track is supported. + */ +void kvm_slot_page_track_add_page(struct kvm *kvm, + struct kvm_memory_slot *slot, gfn_t gfn, + enum kvm_page_track_mode mode) +{ + + if (WARN_ON(!page_track_mode_is_valid(mode))) + return; + + if (WARN_ON(mode == KVM_PAGE_TRACK_WRITE && + !kvm_page_track_write_tracking_enabled(kvm))) + return; + + update_gfn_track(slot, gfn, mode, 1); + + /* + * new track stops large page mapping for the + * tracked page. + */ + kvm_mmu_gfn_disallow_lpage(slot, gfn); + + if (mode == KVM_PAGE_TRACK_WRITE) + if (kvm_mmu_slot_gfn_write_protect(kvm, slot, gfn, PG_LEVEL_4K)) + kvm_flush_remote_tlbs(kvm); +} +EXPORT_SYMBOL_GPL(kvm_slot_page_track_add_page); + +/* + * remove the guest page from the tracking pool which stops the interception + * of corresponding access on that page. It is the opposed operation of + * kvm_slot_page_track_add_page(). + * + * It should be called under the protection both of mmu-lock and kvm->srcu + * or kvm->slots_lock. + * + * @kvm: the guest instance we are interested in. + * @slot: the @gfn belongs to. + * @gfn: the guest page. + * @mode: tracking mode, currently only write track is supported. + */ +void kvm_slot_page_track_remove_page(struct kvm *kvm, + struct kvm_memory_slot *slot, gfn_t gfn, + enum kvm_page_track_mode mode) +{ + if (WARN_ON(!page_track_mode_is_valid(mode))) + return; + + if (WARN_ON(mode == KVM_PAGE_TRACK_WRITE && + !kvm_page_track_write_tracking_enabled(kvm))) + return; + + update_gfn_track(slot, gfn, mode, -1); + + /* + * allow large page mapping for the tracked page + * after the tracker is gone. + */ + kvm_mmu_gfn_allow_lpage(slot, gfn); +} +EXPORT_SYMBOL_GPL(kvm_slot_page_track_remove_page); + +/* + * check if the corresponding access on the specified guest page is tracked. + */ +bool kvm_slot_page_track_is_active(struct kvm *kvm, + const struct kvm_memory_slot *slot, + gfn_t gfn, enum kvm_page_track_mode mode) +{ + int index; + + if (WARN_ON(!page_track_mode_is_valid(mode))) + return false; + + if (!slot) + return false; + + if (mode == KVM_PAGE_TRACK_WRITE && + !kvm_page_track_write_tracking_enabled(kvm)) + return false; + + index = gfn_to_index(gfn, slot->base_gfn, PG_LEVEL_4K); + return !!READ_ONCE(slot->arch.gfn_track[mode][index]); +} + +void kvm_page_track_cleanup(struct kvm *kvm) +{ + struct kvm_page_track_notifier_head *head; + + head = &kvm->arch.track_notifier_head; + cleanup_srcu_struct(&head->track_srcu); +} + +int kvm_page_track_init(struct kvm *kvm) +{ + struct kvm_page_track_notifier_head *head; + + head = &kvm->arch.track_notifier_head; + INIT_HLIST_HEAD(&head->track_notifier_list); + return init_srcu_struct(&head->track_srcu); +} + +/* + * register the notifier so that event interception for the tracked guest + * pages can be received. + */ +void +kvm_page_track_register_notifier(struct kvm *kvm, + struct kvm_page_track_notifier_node *n) +{ + struct kvm_page_track_notifier_head *head; + + head = &kvm->arch.track_notifier_head; + + write_lock(&kvm->mmu_lock); + hlist_add_head_rcu(&n->node, &head->track_notifier_list); + write_unlock(&kvm->mmu_lock); +} +EXPORT_SYMBOL_GPL(kvm_page_track_register_notifier); + +/* + * stop receiving the event interception. It is the opposed operation of + * kvm_page_track_register_notifier(). + */ +void +kvm_page_track_unregister_notifier(struct kvm *kvm, + struct kvm_page_track_notifier_node *n) +{ + struct kvm_page_track_notifier_head *head; + + head = &kvm->arch.track_notifier_head; + + write_lock(&kvm->mmu_lock); + hlist_del_rcu(&n->node); + write_unlock(&kvm->mmu_lock); + synchronize_srcu(&head->track_srcu); +} +EXPORT_SYMBOL_GPL(kvm_page_track_unregister_notifier); + +/* + * Notify the node that write access is intercepted and write emulation is + * finished at this time. + * + * The node should figure out if the written page is the one that node is + * interested in by itself. + */ +void kvm_page_track_write(struct kvm_vcpu *vcpu, gpa_t gpa, const u8 *new, + int bytes) +{ + struct kvm_page_track_notifier_head *head; + struct kvm_page_track_notifier_node *n; + int idx; + + head = &vcpu->kvm->arch.track_notifier_head; + + if (hlist_empty(&head->track_notifier_list)) + return; + + idx = srcu_read_lock(&head->track_srcu); + hlist_for_each_entry_srcu(n, &head->track_notifier_list, node, + srcu_read_lock_held(&head->track_srcu)) + if (n->track_write) + n->track_write(vcpu, gpa, new, bytes, n); + srcu_read_unlock(&head->track_srcu, idx); +} + +/* + * Notify the node that memory slot is being removed or moved so that it can + * drop write-protection for the pages in the memory slot. + * + * The node should figure out it has any write-protected pages in this slot + * by itself. + */ +void kvm_page_track_flush_slot(struct kvm *kvm, struct kvm_memory_slot *slot) +{ + struct kvm_page_track_notifier_head *head; + struct kvm_page_track_notifier_node *n; + int idx; + + head = &kvm->arch.track_notifier_head; + + if (hlist_empty(&head->track_notifier_list)) + return; + + idx = srcu_read_lock(&head->track_srcu); + hlist_for_each_entry_srcu(n, &head->track_notifier_list, node, + srcu_read_lock_held(&head->track_srcu)) + if (n->track_flush_slot) + n->track_flush_slot(kvm, slot, n); + srcu_read_unlock(&head->track_srcu, idx); +} diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h new file mode 100644 index 000000000..1f4f5e703 --- /dev/null +++ b/arch/x86/kvm/mmu/paging_tmpl.h @@ -0,0 +1,1116 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Kernel-based Virtual Machine driver for Linux + * + * This module enables machines with Intel VT-x extensions to run virtual + * machines without emulation or binary translation. + * + * MMU support + * + * Copyright (C) 2006 Qumranet, Inc. + * Copyright 2010 Red Hat, Inc. and/or its affiliates. + * + * Authors: + * Yaniv Kamay <yaniv@qumranet.com> + * Avi Kivity <avi@qumranet.com> + */ + +/* + * The MMU needs to be able to access/walk 32-bit and 64-bit guest page tables, + * as well as guest EPT tables, so the code in this file is compiled thrice, + * once per guest PTE type. The per-type defines are #undef'd at the end. + */ + +#if PTTYPE == 64 + #define pt_element_t u64 + #define guest_walker guest_walker64 + #define FNAME(name) paging##64_##name + #define PT_LEVEL_BITS 9 + #define PT_GUEST_DIRTY_SHIFT PT_DIRTY_SHIFT + #define PT_GUEST_ACCESSED_SHIFT PT_ACCESSED_SHIFT + #define PT_HAVE_ACCESSED_DIRTY(mmu) true + #ifdef CONFIG_X86_64 + #define PT_MAX_FULL_LEVELS PT64_ROOT_MAX_LEVEL + #else + #define PT_MAX_FULL_LEVELS 2 + #endif +#elif PTTYPE == 32 + #define pt_element_t u32 + #define guest_walker guest_walker32 + #define FNAME(name) paging##32_##name + #define PT_LEVEL_BITS 10 + #define PT_MAX_FULL_LEVELS 2 + #define PT_GUEST_DIRTY_SHIFT PT_DIRTY_SHIFT + #define PT_GUEST_ACCESSED_SHIFT PT_ACCESSED_SHIFT + #define PT_HAVE_ACCESSED_DIRTY(mmu) true + + #define PT32_DIR_PSE36_SIZE 4 + #define PT32_DIR_PSE36_SHIFT 13 + #define PT32_DIR_PSE36_MASK \ + (((1ULL << PT32_DIR_PSE36_SIZE) - 1) << PT32_DIR_PSE36_SHIFT) +#elif PTTYPE == PTTYPE_EPT + #define pt_element_t u64 + #define guest_walker guest_walkerEPT + #define FNAME(name) ept_##name + #define PT_LEVEL_BITS 9 + #define PT_GUEST_DIRTY_SHIFT 9 + #define PT_GUEST_ACCESSED_SHIFT 8 + #define PT_HAVE_ACCESSED_DIRTY(mmu) (!(mmu)->cpu_role.base.ad_disabled) + #define PT_MAX_FULL_LEVELS PT64_ROOT_MAX_LEVEL +#else + #error Invalid PTTYPE value +#endif + +/* Common logic, but per-type values. These also need to be undefined. */ +#define PT_BASE_ADDR_MASK ((pt_element_t)(((1ULL << 52) - 1) & ~(u64)(PAGE_SIZE-1))) +#define PT_LVL_ADDR_MASK(lvl) __PT_LVL_ADDR_MASK(PT_BASE_ADDR_MASK, lvl, PT_LEVEL_BITS) +#define PT_LVL_OFFSET_MASK(lvl) __PT_LVL_OFFSET_MASK(PT_BASE_ADDR_MASK, lvl, PT_LEVEL_BITS) +#define PT_INDEX(addr, lvl) __PT_INDEX(addr, lvl, PT_LEVEL_BITS) + +#define PT_GUEST_DIRTY_MASK (1 << PT_GUEST_DIRTY_SHIFT) +#define PT_GUEST_ACCESSED_MASK (1 << PT_GUEST_ACCESSED_SHIFT) + +#define gpte_to_gfn_lvl FNAME(gpte_to_gfn_lvl) +#define gpte_to_gfn(pte) gpte_to_gfn_lvl((pte), PG_LEVEL_4K) + +/* + * The guest_walker structure emulates the behavior of the hardware page + * table walker. + */ +struct guest_walker { + int level; + unsigned max_level; + gfn_t table_gfn[PT_MAX_FULL_LEVELS]; + pt_element_t ptes[PT_MAX_FULL_LEVELS]; + pt_element_t prefetch_ptes[PTE_PREFETCH_NUM]; + gpa_t pte_gpa[PT_MAX_FULL_LEVELS]; + pt_element_t __user *ptep_user[PT_MAX_FULL_LEVELS]; + bool pte_writable[PT_MAX_FULL_LEVELS]; + unsigned int pt_access[PT_MAX_FULL_LEVELS]; + unsigned int pte_access; + gfn_t gfn; + struct x86_exception fault; +}; + +#if PTTYPE == 32 +static inline gfn_t pse36_gfn_delta(u32 gpte) +{ + int shift = 32 - PT32_DIR_PSE36_SHIFT - PAGE_SHIFT; + + return (gpte & PT32_DIR_PSE36_MASK) << shift; +} +#endif + +static gfn_t gpte_to_gfn_lvl(pt_element_t gpte, int lvl) +{ + return (gpte & PT_LVL_ADDR_MASK(lvl)) >> PAGE_SHIFT; +} + +static inline void FNAME(protect_clean_gpte)(struct kvm_mmu *mmu, unsigned *access, + unsigned gpte) +{ + unsigned mask; + + /* dirty bit is not supported, so no need to track it */ + if (!PT_HAVE_ACCESSED_DIRTY(mmu)) + return; + + BUILD_BUG_ON(PT_WRITABLE_MASK != ACC_WRITE_MASK); + + mask = (unsigned)~ACC_WRITE_MASK; + /* Allow write access to dirty gptes */ + mask |= (gpte >> (PT_GUEST_DIRTY_SHIFT - PT_WRITABLE_SHIFT)) & + PT_WRITABLE_MASK; + *access &= mask; +} + +static inline int FNAME(is_present_gpte)(unsigned long pte) +{ +#if PTTYPE != PTTYPE_EPT + return pte & PT_PRESENT_MASK; +#else + return pte & 7; +#endif +} + +static bool FNAME(is_bad_mt_xwr)(struct rsvd_bits_validate *rsvd_check, u64 gpte) +{ +#if PTTYPE != PTTYPE_EPT + return false; +#else + return __is_bad_mt_xwr(rsvd_check, gpte); +#endif +} + +static bool FNAME(is_rsvd_bits_set)(struct kvm_mmu *mmu, u64 gpte, int level) +{ + return __is_rsvd_bits_set(&mmu->guest_rsvd_check, gpte, level) || + FNAME(is_bad_mt_xwr)(&mmu->guest_rsvd_check, gpte); +} + +static bool FNAME(prefetch_invalid_gpte)(struct kvm_vcpu *vcpu, + struct kvm_mmu_page *sp, u64 *spte, + u64 gpte) +{ + if (!FNAME(is_present_gpte)(gpte)) + goto no_present; + + /* Prefetch only accessed entries (unless A/D bits are disabled). */ + if (PT_HAVE_ACCESSED_DIRTY(vcpu->arch.mmu) && + !(gpte & PT_GUEST_ACCESSED_MASK)) + goto no_present; + + if (FNAME(is_rsvd_bits_set)(vcpu->arch.mmu, gpte, PG_LEVEL_4K)) + goto no_present; + + return false; + +no_present: + drop_spte(vcpu->kvm, spte); + return true; +} + +/* + * For PTTYPE_EPT, a page table can be executable but not readable + * on supported processors. Therefore, set_spte does not automatically + * set bit 0 if execute only is supported. Here, we repurpose ACC_USER_MASK + * to signify readability since it isn't used in the EPT case + */ +static inline unsigned FNAME(gpte_access)(u64 gpte) +{ + unsigned access; +#if PTTYPE == PTTYPE_EPT + access = ((gpte & VMX_EPT_WRITABLE_MASK) ? ACC_WRITE_MASK : 0) | + ((gpte & VMX_EPT_EXECUTABLE_MASK) ? ACC_EXEC_MASK : 0) | + ((gpte & VMX_EPT_READABLE_MASK) ? ACC_USER_MASK : 0); +#else + BUILD_BUG_ON(ACC_EXEC_MASK != PT_PRESENT_MASK); + BUILD_BUG_ON(ACC_EXEC_MASK != 1); + access = gpte & (PT_WRITABLE_MASK | PT_USER_MASK | PT_PRESENT_MASK); + /* Combine NX with P (which is set here) to get ACC_EXEC_MASK. */ + access ^= (gpte >> PT64_NX_SHIFT); +#endif + + return access; +} + +static int FNAME(update_accessed_dirty_bits)(struct kvm_vcpu *vcpu, + struct kvm_mmu *mmu, + struct guest_walker *walker, + gpa_t addr, int write_fault) +{ + unsigned level, index; + pt_element_t pte, orig_pte; + pt_element_t __user *ptep_user; + gfn_t table_gfn; + int ret; + + /* dirty/accessed bits are not supported, so no need to update them */ + if (!PT_HAVE_ACCESSED_DIRTY(mmu)) + return 0; + + for (level = walker->max_level; level >= walker->level; --level) { + pte = orig_pte = walker->ptes[level - 1]; + table_gfn = walker->table_gfn[level - 1]; + ptep_user = walker->ptep_user[level - 1]; + index = offset_in_page(ptep_user) / sizeof(pt_element_t); + if (!(pte & PT_GUEST_ACCESSED_MASK)) { + trace_kvm_mmu_set_accessed_bit(table_gfn, index, sizeof(pte)); + pte |= PT_GUEST_ACCESSED_MASK; + } + if (level == walker->level && write_fault && + !(pte & PT_GUEST_DIRTY_MASK)) { + trace_kvm_mmu_set_dirty_bit(table_gfn, index, sizeof(pte)); +#if PTTYPE == PTTYPE_EPT + if (kvm_x86_ops.nested_ops->write_log_dirty(vcpu, addr)) + return -EINVAL; +#endif + pte |= PT_GUEST_DIRTY_MASK; + } + if (pte == orig_pte) + continue; + + /* + * If the slot is read-only, simply do not process the accessed + * and dirty bits. This is the correct thing to do if the slot + * is ROM, and page tables in read-as-ROM/write-as-MMIO slots + * are only supported if the accessed and dirty bits are already + * set in the ROM (so that MMIO writes are never needed). + * + * Note that NPT does not allow this at all and faults, since + * it always wants nested page table entries for the guest + * page tables to be writable. And EPT works but will simply + * overwrite the read-only memory to set the accessed and dirty + * bits. + */ + if (unlikely(!walker->pte_writable[level - 1])) + continue; + + ret = __try_cmpxchg_user(ptep_user, &orig_pte, pte, fault); + if (ret) + return ret; + + kvm_vcpu_mark_page_dirty(vcpu, table_gfn); + walker->ptes[level - 1] = pte; + } + return 0; +} + +static inline unsigned FNAME(gpte_pkeys)(struct kvm_vcpu *vcpu, u64 gpte) +{ + unsigned pkeys = 0; +#if PTTYPE == 64 + pte_t pte = {.pte = gpte}; + + pkeys = pte_flags_pkey(pte_flags(pte)); +#endif + return pkeys; +} + +static inline bool FNAME(is_last_gpte)(struct kvm_mmu *mmu, + unsigned int level, unsigned int gpte) +{ + /* + * For EPT and PAE paging (both variants), bit 7 is either reserved at + * all level or indicates a huge page (ignoring CR3/EPTP). In either + * case, bit 7 being set terminates the walk. + */ +#if PTTYPE == 32 + /* + * 32-bit paging requires special handling because bit 7 is ignored if + * CR4.PSE=0, not reserved. Clear bit 7 in the gpte if the level is + * greater than the last level for which bit 7 is the PAGE_SIZE bit. + * + * The RHS has bit 7 set iff level < (2 + PSE). If it is clear, bit 7 + * is not reserved and does not indicate a large page at this level, + * so clear PT_PAGE_SIZE_MASK in gpte if that is the case. + */ + gpte &= level - (PT32_ROOT_LEVEL + mmu->cpu_role.ext.cr4_pse); +#endif + /* + * PG_LEVEL_4K always terminates. The RHS has bit 7 set + * iff level <= PG_LEVEL_4K, which for our purpose means + * level == PG_LEVEL_4K; set PT_PAGE_SIZE_MASK in gpte then. + */ + gpte |= level - PG_LEVEL_4K - 1; + + return gpte & PT_PAGE_SIZE_MASK; +} +/* + * Fetch a guest pte for a guest virtual address, or for an L2's GPA. + */ +static int FNAME(walk_addr_generic)(struct guest_walker *walker, + struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, + gpa_t addr, u64 access) +{ + int ret; + pt_element_t pte; + pt_element_t __user *ptep_user; + gfn_t table_gfn; + u64 pt_access, pte_access; + unsigned index, accessed_dirty, pte_pkey; + u64 nested_access; + gpa_t pte_gpa; + bool have_ad; + int offset; + u64 walk_nx_mask = 0; + const int write_fault = access & PFERR_WRITE_MASK; + const int user_fault = access & PFERR_USER_MASK; + const int fetch_fault = access & PFERR_FETCH_MASK; + u16 errcode = 0; + gpa_t real_gpa; + gfn_t gfn; + + trace_kvm_mmu_pagetable_walk(addr, access); +retry_walk: + walker->level = mmu->cpu_role.base.level; + pte = kvm_mmu_get_guest_pgd(vcpu, mmu); + have_ad = PT_HAVE_ACCESSED_DIRTY(mmu); + +#if PTTYPE == 64 + walk_nx_mask = 1ULL << PT64_NX_SHIFT; + if (walker->level == PT32E_ROOT_LEVEL) { + pte = mmu->get_pdptr(vcpu, (addr >> 30) & 3); + trace_kvm_mmu_paging_element(pte, walker->level); + if (!FNAME(is_present_gpte)(pte)) + goto error; + --walker->level; + } +#endif + walker->max_level = walker->level; + ASSERT(!(is_long_mode(vcpu) && !is_pae(vcpu))); + + /* + * FIXME: on Intel processors, loads of the PDPTE registers for PAE paging + * by the MOV to CR instruction are treated as reads and do not cause the + * processor to set the dirty flag in any EPT paging-structure entry. + */ + nested_access = (have_ad ? PFERR_WRITE_MASK : 0) | PFERR_USER_MASK; + + pte_access = ~0; + ++walker->level; + + do { + unsigned long host_addr; + + pt_access = pte_access; + --walker->level; + + index = PT_INDEX(addr, walker->level); + table_gfn = gpte_to_gfn(pte); + offset = index * sizeof(pt_element_t); + pte_gpa = gfn_to_gpa(table_gfn) + offset; + + BUG_ON(walker->level < 1); + walker->table_gfn[walker->level - 1] = table_gfn; + walker->pte_gpa[walker->level - 1] = pte_gpa; + + real_gpa = kvm_translate_gpa(vcpu, mmu, gfn_to_gpa(table_gfn), + nested_access, &walker->fault); + + /* + * FIXME: This can happen if emulation (for of an INS/OUTS + * instruction) triggers a nested page fault. The exit + * qualification / exit info field will incorrectly have + * "guest page access" as the nested page fault's cause, + * instead of "guest page structure access". To fix this, + * the x86_exception struct should be augmented with enough + * information to fix the exit_qualification or exit_info_1 + * fields. + */ + if (unlikely(real_gpa == INVALID_GPA)) + return 0; + + host_addr = kvm_vcpu_gfn_to_hva_prot(vcpu, gpa_to_gfn(real_gpa), + &walker->pte_writable[walker->level - 1]); + if (unlikely(kvm_is_error_hva(host_addr))) + goto error; + + ptep_user = (pt_element_t __user *)((void *)host_addr + offset); + if (unlikely(__get_user(pte, ptep_user))) + goto error; + walker->ptep_user[walker->level - 1] = ptep_user; + + trace_kvm_mmu_paging_element(pte, walker->level); + + /* + * Inverting the NX it lets us AND it like other + * permission bits. + */ + pte_access = pt_access & (pte ^ walk_nx_mask); + + if (unlikely(!FNAME(is_present_gpte)(pte))) + goto error; + + if (unlikely(FNAME(is_rsvd_bits_set)(mmu, pte, walker->level))) { + errcode = PFERR_RSVD_MASK | PFERR_PRESENT_MASK; + goto error; + } + + walker->ptes[walker->level - 1] = pte; + + /* Convert to ACC_*_MASK flags for struct guest_walker. */ + walker->pt_access[walker->level - 1] = FNAME(gpte_access)(pt_access ^ walk_nx_mask); + } while (!FNAME(is_last_gpte)(mmu, walker->level, pte)); + + pte_pkey = FNAME(gpte_pkeys)(vcpu, pte); + accessed_dirty = have_ad ? pte_access & PT_GUEST_ACCESSED_MASK : 0; + + /* Convert to ACC_*_MASK flags for struct guest_walker. */ + walker->pte_access = FNAME(gpte_access)(pte_access ^ walk_nx_mask); + errcode = permission_fault(vcpu, mmu, walker->pte_access, pte_pkey, access); + if (unlikely(errcode)) + goto error; + + gfn = gpte_to_gfn_lvl(pte, walker->level); + gfn += (addr & PT_LVL_OFFSET_MASK(walker->level)) >> PAGE_SHIFT; + +#if PTTYPE == 32 + if (walker->level > PG_LEVEL_4K && is_cpuid_PSE36()) + gfn += pse36_gfn_delta(pte); +#endif + + real_gpa = kvm_translate_gpa(vcpu, mmu, gfn_to_gpa(gfn), access, &walker->fault); + if (real_gpa == INVALID_GPA) + return 0; + + walker->gfn = real_gpa >> PAGE_SHIFT; + + if (!write_fault) + FNAME(protect_clean_gpte)(mmu, &walker->pte_access, pte); + else + /* + * On a write fault, fold the dirty bit into accessed_dirty. + * For modes without A/D bits support accessed_dirty will be + * always clear. + */ + accessed_dirty &= pte >> + (PT_GUEST_DIRTY_SHIFT - PT_GUEST_ACCESSED_SHIFT); + + if (unlikely(!accessed_dirty)) { + ret = FNAME(update_accessed_dirty_bits)(vcpu, mmu, walker, + addr, write_fault); + if (unlikely(ret < 0)) + goto error; + else if (ret) + goto retry_walk; + } + + pgprintk("%s: pte %llx pte_access %x pt_access %x\n", + __func__, (u64)pte, walker->pte_access, + walker->pt_access[walker->level - 1]); + return 1; + +error: + errcode |= write_fault | user_fault; + if (fetch_fault && (is_efer_nx(mmu) || is_cr4_smep(mmu))) + errcode |= PFERR_FETCH_MASK; + + walker->fault.vector = PF_VECTOR; + walker->fault.error_code_valid = true; + walker->fault.error_code = errcode; + +#if PTTYPE == PTTYPE_EPT + /* + * Use PFERR_RSVD_MASK in error_code to tell if EPT + * misconfiguration requires to be injected. The detection is + * done by is_rsvd_bits_set() above. + * + * We set up the value of exit_qualification to inject: + * [2:0] - Derive from the access bits. The exit_qualification might be + * out of date if it is serving an EPT misconfiguration. + * [5:3] - Calculated by the page walk of the guest EPT page tables + * [7:8] - Derived from [7:8] of real exit_qualification + * + * The other bits are set to 0. + */ + if (!(errcode & PFERR_RSVD_MASK)) { + vcpu->arch.exit_qualification &= (EPT_VIOLATION_GVA_IS_VALID | + EPT_VIOLATION_GVA_TRANSLATED); + if (write_fault) + vcpu->arch.exit_qualification |= EPT_VIOLATION_ACC_WRITE; + if (user_fault) + vcpu->arch.exit_qualification |= EPT_VIOLATION_ACC_READ; + if (fetch_fault) + vcpu->arch.exit_qualification |= EPT_VIOLATION_ACC_INSTR; + + /* + * Note, pte_access holds the raw RWX bits from the EPTE, not + * ACC_*_MASK flags! + */ + vcpu->arch.exit_qualification |= (pte_access & VMX_EPT_RWX_MASK) << + EPT_VIOLATION_RWX_SHIFT; + } +#endif + walker->fault.address = addr; + walker->fault.nested_page_fault = mmu != vcpu->arch.walk_mmu; + walker->fault.async_page_fault = false; + + trace_kvm_mmu_walker_error(walker->fault.error_code); + return 0; +} + +static int FNAME(walk_addr)(struct guest_walker *walker, + struct kvm_vcpu *vcpu, gpa_t addr, u64 access) +{ + return FNAME(walk_addr_generic)(walker, vcpu, vcpu->arch.mmu, addr, + access); +} + +static bool +FNAME(prefetch_gpte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, + u64 *spte, pt_element_t gpte, bool no_dirty_log) +{ + struct kvm_memory_slot *slot; + unsigned pte_access; + gfn_t gfn; + kvm_pfn_t pfn; + + if (FNAME(prefetch_invalid_gpte)(vcpu, sp, spte, gpte)) + return false; + + pgprintk("%s: gpte %llx spte %p\n", __func__, (u64)gpte, spte); + + gfn = gpte_to_gfn(gpte); + pte_access = sp->role.access & FNAME(gpte_access)(gpte); + FNAME(protect_clean_gpte)(vcpu->arch.mmu, &pte_access, gpte); + + slot = gfn_to_memslot_dirty_bitmap(vcpu, gfn, + no_dirty_log && (pte_access & ACC_WRITE_MASK)); + if (!slot) + return false; + + pfn = gfn_to_pfn_memslot_atomic(slot, gfn); + if (is_error_pfn(pfn)) + return false; + + mmu_set_spte(vcpu, slot, spte, pte_access, gfn, pfn, NULL); + kvm_release_pfn_clean(pfn); + return true; +} + +static bool FNAME(gpte_changed)(struct kvm_vcpu *vcpu, + struct guest_walker *gw, int level) +{ + pt_element_t curr_pte; + gpa_t base_gpa, pte_gpa = gw->pte_gpa[level - 1]; + u64 mask; + int r, index; + + if (level == PG_LEVEL_4K) { + mask = PTE_PREFETCH_NUM * sizeof(pt_element_t) - 1; + base_gpa = pte_gpa & ~mask; + index = (pte_gpa - base_gpa) / sizeof(pt_element_t); + + r = kvm_vcpu_read_guest_atomic(vcpu, base_gpa, + gw->prefetch_ptes, sizeof(gw->prefetch_ptes)); + curr_pte = gw->prefetch_ptes[index]; + } else + r = kvm_vcpu_read_guest_atomic(vcpu, pte_gpa, + &curr_pte, sizeof(curr_pte)); + + return r || curr_pte != gw->ptes[level - 1]; +} + +static void FNAME(pte_prefetch)(struct kvm_vcpu *vcpu, struct guest_walker *gw, + u64 *sptep) +{ + struct kvm_mmu_page *sp; + pt_element_t *gptep = gw->prefetch_ptes; + u64 *spte; + int i; + + sp = sptep_to_sp(sptep); + + if (sp->role.level > PG_LEVEL_4K) + return; + + /* + * If addresses are being invalidated, skip prefetching to avoid + * accidentally prefetching those addresses. + */ + if (unlikely(vcpu->kvm->mmu_invalidate_in_progress)) + return; + + if (sp->role.direct) + return __direct_pte_prefetch(vcpu, sp, sptep); + + i = spte_index(sptep) & ~(PTE_PREFETCH_NUM - 1); + spte = sp->spt + i; + + for (i = 0; i < PTE_PREFETCH_NUM; i++, spte++) { + if (spte == sptep) + continue; + + if (is_shadow_present_pte(*spte)) + continue; + + if (!FNAME(prefetch_gpte)(vcpu, sp, spte, gptep[i], true)) + break; + } +} + +/* + * Fetch a shadow pte for a specific level in the paging hierarchy. + * If the guest tries to write a write-protected page, we need to + * emulate this operation, return 1 to indicate this case. + */ +static int FNAME(fetch)(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault, + struct guest_walker *gw) +{ + struct kvm_mmu_page *sp = NULL; + struct kvm_shadow_walk_iterator it; + unsigned int direct_access, access; + int top_level, ret; + gfn_t base_gfn = fault->gfn; + + WARN_ON_ONCE(gw->gfn != base_gfn); + direct_access = gw->pte_access; + + top_level = vcpu->arch.mmu->cpu_role.base.level; + if (top_level == PT32E_ROOT_LEVEL) + top_level = PT32_ROOT_LEVEL; + /* + * Verify that the top-level gpte is still there. Since the page + * is a root page, it is either write protected (and cannot be + * changed from now on) or it is invalid (in which case, we don't + * really care if it changes underneath us after this point). + */ + if (FNAME(gpte_changed)(vcpu, gw, top_level)) + goto out_gpte_changed; + + if (WARN_ON(!VALID_PAGE(vcpu->arch.mmu->root.hpa))) + goto out_gpte_changed; + + for (shadow_walk_init(&it, vcpu, fault->addr); + shadow_walk_okay(&it) && it.level > gw->level; + shadow_walk_next(&it)) { + gfn_t table_gfn; + + clear_sp_write_flooding_count(it.sptep); + + table_gfn = gw->table_gfn[it.level - 2]; + access = gw->pt_access[it.level - 2]; + sp = kvm_mmu_get_child_sp(vcpu, it.sptep, table_gfn, + false, access); + + if (sp != ERR_PTR(-EEXIST)) { + /* + * We must synchronize the pagetable before linking it + * because the guest doesn't need to flush tlb when + * the gpte is changed from non-present to present. + * Otherwise, the guest may use the wrong mapping. + * + * For PG_LEVEL_4K, kvm_mmu_get_page() has already + * synchronized it transiently via kvm_sync_page(). + * + * For higher level pagetable, we synchronize it via + * the slower mmu_sync_children(). If it needs to + * break, some progress has been made; return + * RET_PF_RETRY and retry on the next #PF. + * KVM_REQ_MMU_SYNC is not necessary but it + * expedites the process. + */ + if (sp->unsync_children && + mmu_sync_children(vcpu, sp, false)) + return RET_PF_RETRY; + } + + /* + * Verify that the gpte in the page we've just write + * protected is still there. + */ + if (FNAME(gpte_changed)(vcpu, gw, it.level - 1)) + goto out_gpte_changed; + + if (sp != ERR_PTR(-EEXIST)) + link_shadow_page(vcpu, it.sptep, sp); + } + + kvm_mmu_hugepage_adjust(vcpu, fault); + + trace_kvm_mmu_spte_requested(fault); + + for (; shadow_walk_okay(&it); shadow_walk_next(&it)) { + clear_sp_write_flooding_count(it.sptep); + + /* + * We cannot overwrite existing page tables with an NX + * large page, as the leaf could be executable. + */ + if (fault->nx_huge_page_workaround_enabled) + disallowed_hugepage_adjust(fault, *it.sptep, it.level); + + base_gfn = fault->gfn & ~(KVM_PAGES_PER_HPAGE(it.level) - 1); + if (it.level == fault->goal_level) + break; + + validate_direct_spte(vcpu, it.sptep, direct_access); + + sp = kvm_mmu_get_child_sp(vcpu, it.sptep, base_gfn, + true, direct_access); + if (sp == ERR_PTR(-EEXIST)) + continue; + + link_shadow_page(vcpu, it.sptep, sp); + if (fault->huge_page_disallowed && + fault->req_level >= it.level) + account_huge_nx_page(vcpu->kvm, sp); + } + + if (WARN_ON_ONCE(it.level != fault->goal_level)) + return -EFAULT; + + ret = mmu_set_spte(vcpu, fault->slot, it.sptep, gw->pte_access, + base_gfn, fault->pfn, fault); + if (ret == RET_PF_SPURIOUS) + return ret; + + FNAME(pte_prefetch)(vcpu, gw, it.sptep); + return ret; + +out_gpte_changed: + return RET_PF_RETRY; +} + + /* + * To see whether the mapped gfn can write its page table in the current + * mapping. + * + * It is the helper function of FNAME(page_fault). When guest uses large page + * size to map the writable gfn which is used as current page table, we should + * force kvm to use small page size to map it because new shadow page will be + * created when kvm establishes shadow page table that stop kvm using large + * page size. Do it early can avoid unnecessary #PF and emulation. + * + * @write_fault_to_shadow_pgtable will return true if the fault gfn is + * currently used as its page table. + * + * Note: the PDPT page table is not checked for PAE-32 bit guest. It is ok + * since the PDPT is always shadowed, that means, we can not use large page + * size to map the gfn which is used as PDPT. + */ +static bool +FNAME(is_self_change_mapping)(struct kvm_vcpu *vcpu, + struct guest_walker *walker, bool user_fault, + bool *write_fault_to_shadow_pgtable) +{ + int level; + gfn_t mask = ~(KVM_PAGES_PER_HPAGE(walker->level) - 1); + bool self_changed = false; + + if (!(walker->pte_access & ACC_WRITE_MASK || + (!is_cr0_wp(vcpu->arch.mmu) && !user_fault))) + return false; + + for (level = walker->level; level <= walker->max_level; level++) { + gfn_t gfn = walker->gfn ^ walker->table_gfn[level - 1]; + + self_changed |= !(gfn & mask); + *write_fault_to_shadow_pgtable |= !gfn; + } + + return self_changed; +} + +/* + * Page fault handler. There are several causes for a page fault: + * - there is no shadow pte for the guest pte + * - write access through a shadow pte marked read only so that we can set + * the dirty bit + * - write access to a shadow pte marked read only so we can update the page + * dirty bitmap, when userspace requests it + * - mmio access; in this case we will never install a present shadow pte + * - normal guest page fault due to the guest pte marked not present, not + * writable, or not executable + * + * Returns: 1 if we need to emulate the instruction, 0 otherwise, or + * a negative value on error. + */ +static int FNAME(page_fault)(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) +{ + struct guest_walker walker; + int r; + unsigned long mmu_seq; + bool is_self_change_mapping; + + pgprintk("%s: addr %lx err %x\n", __func__, fault->addr, fault->error_code); + WARN_ON_ONCE(fault->is_tdp); + + /* + * Look up the guest pte for the faulting address. + * If PFEC.RSVD is set, this is a shadow page fault. + * The bit needs to be cleared before walking guest page tables. + */ + r = FNAME(walk_addr)(&walker, vcpu, fault->addr, + fault->error_code & ~PFERR_RSVD_MASK); + + /* + * The page is not mapped by the guest. Let the guest handle it. + */ + if (!r) { + pgprintk("%s: guest page fault\n", __func__); + if (!fault->prefetch) + kvm_inject_emulated_page_fault(vcpu, &walker.fault); + + return RET_PF_RETRY; + } + + fault->gfn = walker.gfn; + fault->slot = kvm_vcpu_gfn_to_memslot(vcpu, fault->gfn); + + if (page_fault_handle_page_track(vcpu, fault)) { + shadow_page_table_clear_flood(vcpu, fault->addr); + return RET_PF_EMULATE; + } + + r = mmu_topup_memory_caches(vcpu, true); + if (r) + return r; + + vcpu->arch.write_fault_to_shadow_pgtable = false; + + is_self_change_mapping = FNAME(is_self_change_mapping)(vcpu, + &walker, fault->user, &vcpu->arch.write_fault_to_shadow_pgtable); + + if (is_self_change_mapping) + fault->max_level = PG_LEVEL_4K; + else + fault->max_level = walker.level; + + mmu_seq = vcpu->kvm->mmu_invalidate_seq; + smp_rmb(); + + r = kvm_faultin_pfn(vcpu, fault); + if (r != RET_PF_CONTINUE) + return r; + + r = handle_abnormal_pfn(vcpu, fault, walker.pte_access); + if (r != RET_PF_CONTINUE) + return r; + + /* + * Do not change pte_access if the pfn is a mmio page, otherwise + * we will cache the incorrect access into mmio spte. + */ + if (fault->write && !(walker.pte_access & ACC_WRITE_MASK) && + !is_cr0_wp(vcpu->arch.mmu) && !fault->user && fault->slot) { + walker.pte_access |= ACC_WRITE_MASK; + walker.pte_access &= ~ACC_USER_MASK; + + /* + * If we converted a user page to a kernel page, + * so that the kernel can write to it when cr0.wp=0, + * then we should prevent the kernel from executing it + * if SMEP is enabled. + */ + if (is_cr4_smep(vcpu->arch.mmu)) + walker.pte_access &= ~ACC_EXEC_MASK; + } + + r = RET_PF_RETRY; + write_lock(&vcpu->kvm->mmu_lock); + + if (is_page_fault_stale(vcpu, fault, mmu_seq)) + goto out_unlock; + + r = make_mmu_pages_available(vcpu); + if (r) + goto out_unlock; + r = FNAME(fetch)(vcpu, fault, &walker); + +out_unlock: + write_unlock(&vcpu->kvm->mmu_lock); + kvm_release_pfn_clean(fault->pfn); + return r; +} + +static gpa_t FNAME(get_level1_sp_gpa)(struct kvm_mmu_page *sp) +{ + int offset = 0; + + WARN_ON(sp->role.level != PG_LEVEL_4K); + + if (PTTYPE == 32) + offset = sp->role.quadrant << SPTE_LEVEL_BITS; + + return gfn_to_gpa(sp->gfn) + offset * sizeof(pt_element_t); +} + +static void FNAME(invlpg)(struct kvm_vcpu *vcpu, gva_t gva, hpa_t root_hpa) +{ + struct kvm_shadow_walk_iterator iterator; + struct kvm_mmu_page *sp; + u64 old_spte; + int level; + u64 *sptep; + + vcpu_clear_mmio_info(vcpu, gva); + + /* + * No need to check return value here, rmap_can_add() can + * help us to skip pte prefetch later. + */ + mmu_topup_memory_caches(vcpu, true); + + if (!VALID_PAGE(root_hpa)) { + WARN_ON(1); + return; + } + + write_lock(&vcpu->kvm->mmu_lock); + for_each_shadow_entry_using_root(vcpu, root_hpa, gva, iterator) { + level = iterator.level; + sptep = iterator.sptep; + + sp = sptep_to_sp(sptep); + old_spte = *sptep; + if (is_last_spte(old_spte, level)) { + pt_element_t gpte; + gpa_t pte_gpa; + + if (!sp->unsync) + break; + + pte_gpa = FNAME(get_level1_sp_gpa)(sp); + pte_gpa += spte_index(sptep) * sizeof(pt_element_t); + + mmu_page_zap_pte(vcpu->kvm, sp, sptep, NULL); + if (is_shadow_present_pte(old_spte)) + kvm_flush_remote_tlbs_with_address(vcpu->kvm, + sp->gfn, KVM_PAGES_PER_HPAGE(sp->role.level)); + + if (!rmap_can_add(vcpu)) + break; + + if (kvm_vcpu_read_guest_atomic(vcpu, pte_gpa, &gpte, + sizeof(pt_element_t))) + break; + + FNAME(prefetch_gpte)(vcpu, sp, sptep, gpte, false); + } + + if (!sp->unsync_children) + break; + } + write_unlock(&vcpu->kvm->mmu_lock); +} + +/* Note, @addr is a GPA when gva_to_gpa() translates an L2 GPA to an L1 GPA. */ +static gpa_t FNAME(gva_to_gpa)(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, + gpa_t addr, u64 access, + struct x86_exception *exception) +{ + struct guest_walker walker; + gpa_t gpa = INVALID_GPA; + int r; + +#ifndef CONFIG_X86_64 + /* A 64-bit GVA should be impossible on 32-bit KVM. */ + WARN_ON_ONCE((addr >> 32) && mmu == vcpu->arch.walk_mmu); +#endif + + r = FNAME(walk_addr_generic)(&walker, vcpu, mmu, addr, access); + + if (r) { + gpa = gfn_to_gpa(walker.gfn); + gpa |= addr & ~PAGE_MASK; + } else if (exception) + *exception = walker.fault; + + return gpa; +} + +/* + * Using the information in sp->shadowed_translation (kvm_mmu_page_get_gfn()) is + * safe because: + * - The spte has a reference to the struct page, so the pfn for a given gfn + * can't change unless all sptes pointing to it are nuked first. + * + * Returns + * < 0: the sp should be zapped + * 0: the sp is synced and no tlb flushing is required + * > 0: the sp is synced and tlb flushing is required + */ +static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp) +{ + union kvm_mmu_page_role root_role = vcpu->arch.mmu->root_role; + int i; + bool host_writable; + gpa_t first_pte_gpa; + bool flush = false; + + /* + * Ignore various flags when verifying that it's safe to sync a shadow + * page using the current MMU context. + * + * - level: not part of the overall MMU role and will never match as the MMU's + * level tracks the root level + * - access: updated based on the new guest PTE + * - quadrant: not part of the overall MMU role (similar to level) + */ + const union kvm_mmu_page_role sync_role_ign = { + .level = 0xf, + .access = 0x7, + .quadrant = 0x3, + .passthrough = 0x1, + }; + + /* + * Direct pages can never be unsync, and KVM should never attempt to + * sync a shadow page for a different MMU context, e.g. if the role + * differs then the memslot lookup (SMM vs. non-SMM) will be bogus, the + * reserved bits checks will be wrong, etc... + */ + if (WARN_ON_ONCE(sp->role.direct || + (sp->role.word ^ root_role.word) & ~sync_role_ign.word)) + return -1; + + first_pte_gpa = FNAME(get_level1_sp_gpa)(sp); + + for (i = 0; i < SPTE_ENT_PER_PAGE; i++) { + u64 *sptep, spte; + struct kvm_memory_slot *slot; + unsigned pte_access; + pt_element_t gpte; + gpa_t pte_gpa; + gfn_t gfn; + + if (!sp->spt[i]) + continue; + + pte_gpa = first_pte_gpa + i * sizeof(pt_element_t); + + if (kvm_vcpu_read_guest_atomic(vcpu, pte_gpa, &gpte, + sizeof(pt_element_t))) + return -1; + + if (FNAME(prefetch_invalid_gpte)(vcpu, sp, &sp->spt[i], gpte)) { + flush = true; + continue; + } + + gfn = gpte_to_gfn(gpte); + pte_access = sp->role.access; + pte_access &= FNAME(gpte_access)(gpte); + FNAME(protect_clean_gpte)(vcpu->arch.mmu, &pte_access, gpte); + + if (sync_mmio_spte(vcpu, &sp->spt[i], gfn, pte_access)) + continue; + + /* + * Drop the SPTE if the new protections would result in a RWX=0 + * SPTE or if the gfn is changing. The RWX=0 case only affects + * EPT with execute-only support, i.e. EPT without an effective + * "present" bit, as all other paging modes will create a + * read-only SPTE if pte_access is zero. + */ + if ((!pte_access && !shadow_present_mask) || + gfn != kvm_mmu_page_get_gfn(sp, i)) { + drop_spte(vcpu->kvm, &sp->spt[i]); + flush = true; + continue; + } + + /* Update the shadowed access bits in case they changed. */ + kvm_mmu_page_set_access(sp, i, pte_access); + + sptep = &sp->spt[i]; + spte = *sptep; + host_writable = spte & shadow_host_writable_mask; + slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn); + make_spte(vcpu, sp, slot, pte_access, gfn, + spte_to_pfn(spte), spte, true, false, + host_writable, &spte); + + flush |= mmu_spte_update(sptep, spte); + } + + /* + * Note, any flush is purely for KVM's correctness, e.g. when dropping + * an existing SPTE or clearing W/A/D bits to ensure an mmu_notifier + * unmap or dirty logging event doesn't fail to flush. The guest is + * responsible for flushing the TLB to ensure any changes in protection + * bits are recognized, i.e. until the guest flushes or page faults on + * a relevant address, KVM is architecturally allowed to let vCPUs use + * cached translations with the old protection bits. + */ + return flush; +} + +#undef pt_element_t +#undef guest_walker +#undef FNAME +#undef PT_BASE_ADDR_MASK +#undef PT_INDEX +#undef PT_LVL_ADDR_MASK +#undef PT_LVL_OFFSET_MASK +#undef PT_LEVEL_BITS +#undef PT_MAX_FULL_LEVELS +#undef gpte_to_gfn +#undef gpte_to_gfn_lvl +#undef PT_GUEST_ACCESSED_MASK +#undef PT_GUEST_DIRTY_MASK +#undef PT_GUEST_DIRTY_SHIFT +#undef PT_GUEST_ACCESSED_SHIFT +#undef PT_HAVE_ACCESSED_DIRTY diff --git a/arch/x86/kvm/mmu/spte.c b/arch/x86/kvm/mmu/spte.c new file mode 100644 index 000000000..2e08b2a45 --- /dev/null +++ b/arch/x86/kvm/mmu/spte.c @@ -0,0 +1,507 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Kernel-based Virtual Machine driver for Linux + * + * Macros and functions to access KVM PTEs (also known as SPTEs) + * + * Copyright (C) 2006 Qumranet, Inc. + * Copyright 2020 Red Hat, Inc. and/or its affiliates. + */ + + +#include <linux/kvm_host.h> +#include "mmu.h" +#include "mmu_internal.h" +#include "x86.h" +#include "spte.h" + +#include <asm/e820/api.h> +#include <asm/memtype.h> +#include <asm/vmx.h> + +bool __read_mostly enable_mmio_caching = true; +static bool __ro_after_init allow_mmio_caching; +module_param_named(mmio_caching, enable_mmio_caching, bool, 0444); +EXPORT_SYMBOL_GPL(enable_mmio_caching); + +u64 __read_mostly shadow_host_writable_mask; +u64 __read_mostly shadow_mmu_writable_mask; +u64 __read_mostly shadow_nx_mask; +u64 __read_mostly shadow_x_mask; /* mutual exclusive with nx_mask */ +u64 __read_mostly shadow_user_mask; +u64 __read_mostly shadow_accessed_mask; +u64 __read_mostly shadow_dirty_mask; +u64 __read_mostly shadow_mmio_value; +u64 __read_mostly shadow_mmio_mask; +u64 __read_mostly shadow_mmio_access_mask; +u64 __read_mostly shadow_present_mask; +u64 __read_mostly shadow_memtype_mask; +u64 __read_mostly shadow_me_value; +u64 __read_mostly shadow_me_mask; +u64 __read_mostly shadow_acc_track_mask; + +u64 __read_mostly shadow_nonpresent_or_rsvd_mask; +u64 __read_mostly shadow_nonpresent_or_rsvd_lower_gfn_mask; + +u8 __read_mostly shadow_phys_bits; + +void __init kvm_mmu_spte_module_init(void) +{ + /* + * Snapshot userspace's desire to allow MMIO caching. Whether or not + * KVM can actually enable MMIO caching depends on vendor-specific + * hardware capabilities and other module params that can't be resolved + * until the vendor module is loaded, i.e. enable_mmio_caching can and + * will change when the vendor module is (re)loaded. + */ + allow_mmio_caching = enable_mmio_caching; +} + +static u64 generation_mmio_spte_mask(u64 gen) +{ + u64 mask; + + WARN_ON(gen & ~MMIO_SPTE_GEN_MASK); + + mask = (gen << MMIO_SPTE_GEN_LOW_SHIFT) & MMIO_SPTE_GEN_LOW_MASK; + mask |= (gen << MMIO_SPTE_GEN_HIGH_SHIFT) & MMIO_SPTE_GEN_HIGH_MASK; + return mask; +} + +u64 make_mmio_spte(struct kvm_vcpu *vcpu, u64 gfn, unsigned int access) +{ + u64 gen = kvm_vcpu_memslots(vcpu)->generation & MMIO_SPTE_GEN_MASK; + u64 spte = generation_mmio_spte_mask(gen); + u64 gpa = gfn << PAGE_SHIFT; + + WARN_ON_ONCE(!shadow_mmio_value); + + access &= shadow_mmio_access_mask; + spte |= shadow_mmio_value | access; + spte |= gpa | shadow_nonpresent_or_rsvd_mask; + spte |= (gpa & shadow_nonpresent_or_rsvd_mask) + << SHADOW_NONPRESENT_OR_RSVD_MASK_LEN; + + return spte; +} + +static bool kvm_is_mmio_pfn(kvm_pfn_t pfn) +{ + if (pfn_valid(pfn)) + return !is_zero_pfn(pfn) && PageReserved(pfn_to_page(pfn)) && + /* + * Some reserved pages, such as those from NVDIMM + * DAX devices, are not for MMIO, and can be mapped + * with cached memory type for better performance. + * However, the above check misconceives those pages + * as MMIO, and results in KVM mapping them with UC + * memory type, which would hurt the performance. + * Therefore, we check the host memory type in addition + * and only treat UC/UC-/WC pages as MMIO. + */ + (!pat_enabled() || pat_pfn_immune_to_uc_mtrr(pfn)); + + return !e820__mapped_raw_any(pfn_to_hpa(pfn), + pfn_to_hpa(pfn + 1) - 1, + E820_TYPE_RAM); +} + +/* + * Returns true if the SPTE has bits that may be set without holding mmu_lock. + * The caller is responsible for checking if the SPTE is shadow-present, and + * for determining whether or not the caller cares about non-leaf SPTEs. + */ +bool spte_has_volatile_bits(u64 spte) +{ + /* + * Always atomically update spte if it can be updated + * out of mmu-lock, it can ensure dirty bit is not lost, + * also, it can help us to get a stable is_writable_pte() + * to ensure tlb flush is not missed. + */ + if (!is_writable_pte(spte) && is_mmu_writable_spte(spte)) + return true; + + if (is_access_track_spte(spte)) + return true; + + if (spte_ad_enabled(spte)) { + if (!(spte & shadow_accessed_mask) || + (is_writable_pte(spte) && !(spte & shadow_dirty_mask))) + return true; + } + + return false; +} + +bool make_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, + const struct kvm_memory_slot *slot, + unsigned int pte_access, gfn_t gfn, kvm_pfn_t pfn, + u64 old_spte, bool prefetch, bool can_unsync, + bool host_writable, u64 *new_spte) +{ + int level = sp->role.level; + u64 spte = SPTE_MMU_PRESENT_MASK; + bool wrprot = false; + + WARN_ON_ONCE(!pte_access && !shadow_present_mask); + + if (sp->role.ad_disabled) + spte |= SPTE_TDP_AD_DISABLED_MASK; + else if (kvm_mmu_page_ad_need_write_protect(sp)) + spte |= SPTE_TDP_AD_WRPROT_ONLY_MASK; + + /* + * For the EPT case, shadow_present_mask is 0 if hardware + * supports exec-only page table entries. In that case, + * ACC_USER_MASK and shadow_user_mask are used to represent + * read access. See FNAME(gpte_access) in paging_tmpl.h. + */ + spte |= shadow_present_mask; + if (!prefetch) + spte |= spte_shadow_accessed_mask(spte); + + if (level > PG_LEVEL_4K && (pte_access & ACC_EXEC_MASK) && + is_nx_huge_page_enabled(vcpu->kvm)) { + pte_access &= ~ACC_EXEC_MASK; + } + + if (pte_access & ACC_EXEC_MASK) + spte |= shadow_x_mask; + else + spte |= shadow_nx_mask; + + if (pte_access & ACC_USER_MASK) + spte |= shadow_user_mask; + + if (level > PG_LEVEL_4K) + spte |= PT_PAGE_SIZE_MASK; + + if (shadow_memtype_mask) + spte |= static_call(kvm_x86_get_mt_mask)(vcpu, gfn, + kvm_is_mmio_pfn(pfn)); + if (host_writable) + spte |= shadow_host_writable_mask; + else + pte_access &= ~ACC_WRITE_MASK; + + if (shadow_me_value && !kvm_is_mmio_pfn(pfn)) + spte |= shadow_me_value; + + spte |= (u64)pfn << PAGE_SHIFT; + + if (pte_access & ACC_WRITE_MASK) { + spte |= PT_WRITABLE_MASK | shadow_mmu_writable_mask; + + /* + * Optimization: for pte sync, if spte was writable the hash + * lookup is unnecessary (and expensive). Write protection + * is responsibility of kvm_mmu_get_page / kvm_mmu_sync_roots. + * Same reasoning can be applied to dirty page accounting. + */ + if (is_writable_pte(old_spte)) + goto out; + + /* + * Unsync shadow pages that are reachable by the new, writable + * SPTE. Write-protect the SPTE if the page can't be unsync'd, + * e.g. it's write-tracked (upper-level SPs) or has one or more + * shadow pages and unsync'ing pages is not allowed. + */ + if (mmu_try_to_unsync_pages(vcpu->kvm, slot, gfn, can_unsync, prefetch)) { + pgprintk("%s: found shadow page for %llx, marking ro\n", + __func__, gfn); + wrprot = true; + pte_access &= ~ACC_WRITE_MASK; + spte &= ~(PT_WRITABLE_MASK | shadow_mmu_writable_mask); + } + } + + if (pte_access & ACC_WRITE_MASK) + spte |= spte_shadow_dirty_mask(spte); + +out: + if (prefetch) + spte = mark_spte_for_access_track(spte); + + WARN_ONCE(is_rsvd_spte(&vcpu->arch.mmu->shadow_zero_check, spte, level), + "spte = 0x%llx, level = %d, rsvd bits = 0x%llx", spte, level, + get_rsvd_bits(&vcpu->arch.mmu->shadow_zero_check, spte, level)); + + if ((spte & PT_WRITABLE_MASK) && kvm_slot_dirty_track_enabled(slot)) { + /* Enforced by kvm_mmu_hugepage_adjust. */ + WARN_ON(level > PG_LEVEL_4K); + mark_page_dirty_in_slot(vcpu->kvm, slot, gfn); + } + + *new_spte = spte; + return wrprot; +} + +static u64 make_spte_executable(u64 spte) +{ + bool is_access_track = is_access_track_spte(spte); + + if (is_access_track) + spte = restore_acc_track_spte(spte); + + spte &= ~shadow_nx_mask; + spte |= shadow_x_mask; + + if (is_access_track) + spte = mark_spte_for_access_track(spte); + + return spte; +} + +/* + * Construct an SPTE that maps a sub-page of the given huge page SPTE where + * `index` identifies which sub-page. + * + * This is used during huge page splitting to build the SPTEs that make up the + * new page table. + */ +u64 make_huge_page_split_spte(struct kvm *kvm, u64 huge_spte, union kvm_mmu_page_role role, + int index) +{ + u64 child_spte; + + if (WARN_ON_ONCE(!is_shadow_present_pte(huge_spte))) + return 0; + + if (WARN_ON_ONCE(!is_large_pte(huge_spte))) + return 0; + + child_spte = huge_spte; + + /* + * The child_spte already has the base address of the huge page being + * split. So we just have to OR in the offset to the page at the next + * lower level for the given index. + */ + child_spte |= (index * KVM_PAGES_PER_HPAGE(role.level)) << PAGE_SHIFT; + + if (role.level == PG_LEVEL_4K) { + child_spte &= ~PT_PAGE_SIZE_MASK; + + /* + * When splitting to a 4K page where execution is allowed, mark + * the page executable as the NX hugepage mitigation no longer + * applies. + */ + if ((role.access & ACC_EXEC_MASK) && is_nx_huge_page_enabled(kvm)) + child_spte = make_spte_executable(child_spte); + } + + return child_spte; +} + + +u64 make_nonleaf_spte(u64 *child_pt, bool ad_disabled) +{ + u64 spte = SPTE_MMU_PRESENT_MASK; + + spte |= __pa(child_pt) | shadow_present_mask | PT_WRITABLE_MASK | + shadow_user_mask | shadow_x_mask | shadow_me_value; + + if (ad_disabled) + spte |= SPTE_TDP_AD_DISABLED_MASK; + else + spte |= shadow_accessed_mask; + + return spte; +} + +u64 kvm_mmu_changed_pte_notifier_make_spte(u64 old_spte, kvm_pfn_t new_pfn) +{ + u64 new_spte; + + new_spte = old_spte & ~SPTE_BASE_ADDR_MASK; + new_spte |= (u64)new_pfn << PAGE_SHIFT; + + new_spte &= ~PT_WRITABLE_MASK; + new_spte &= ~shadow_host_writable_mask; + new_spte &= ~shadow_mmu_writable_mask; + + new_spte = mark_spte_for_access_track(new_spte); + + return new_spte; +} + +u64 mark_spte_for_access_track(u64 spte) +{ + if (spte_ad_enabled(spte)) + return spte & ~shadow_accessed_mask; + + if (is_access_track_spte(spte)) + return spte; + + check_spte_writable_invariants(spte); + + WARN_ONCE(spte & (SHADOW_ACC_TRACK_SAVED_BITS_MASK << + SHADOW_ACC_TRACK_SAVED_BITS_SHIFT), + "kvm: Access Tracking saved bit locations are not zero\n"); + + spte |= (spte & SHADOW_ACC_TRACK_SAVED_BITS_MASK) << + SHADOW_ACC_TRACK_SAVED_BITS_SHIFT; + spte &= ~shadow_acc_track_mask; + + return spte; +} + +void kvm_mmu_set_mmio_spte_mask(u64 mmio_value, u64 mmio_mask, u64 access_mask) +{ + BUG_ON((u64)(unsigned)access_mask != access_mask); + WARN_ON(mmio_value & shadow_nonpresent_or_rsvd_lower_gfn_mask); + + /* + * Reset to the original module param value to honor userspace's desire + * to (dis)allow MMIO caching. Update the param itself so that + * userspace can see whether or not KVM is actually using MMIO caching. + */ + enable_mmio_caching = allow_mmio_caching; + if (!enable_mmio_caching) + mmio_value = 0; + + /* + * The mask must contain only bits that are carved out specifically for + * the MMIO SPTE mask, e.g. to ensure there's no overlap with the MMIO + * generation. + */ + if (WARN_ON(mmio_mask & ~SPTE_MMIO_ALLOWED_MASK)) + mmio_value = 0; + + /* + * Disable MMIO caching if the MMIO value collides with the bits that + * are used to hold the relocated GFN when the L1TF mitigation is + * enabled. This should never fire as there is no known hardware that + * can trigger this condition, e.g. SME/SEV CPUs that require a custom + * MMIO value are not susceptible to L1TF. + */ + if (WARN_ON(mmio_value & (shadow_nonpresent_or_rsvd_mask << + SHADOW_NONPRESENT_OR_RSVD_MASK_LEN))) + mmio_value = 0; + + /* + * The masked MMIO value must obviously match itself and a removed SPTE + * must not get a false positive. Removed SPTEs and MMIO SPTEs should + * never collide as MMIO must set some RWX bits, and removed SPTEs must + * not set any RWX bits. + */ + if (WARN_ON((mmio_value & mmio_mask) != mmio_value) || + WARN_ON(mmio_value && (REMOVED_SPTE & mmio_mask) == mmio_value)) + mmio_value = 0; + + if (!mmio_value) + enable_mmio_caching = false; + + shadow_mmio_value = mmio_value; + shadow_mmio_mask = mmio_mask; + shadow_mmio_access_mask = access_mask; +} +EXPORT_SYMBOL_GPL(kvm_mmu_set_mmio_spte_mask); + +void kvm_mmu_set_me_spte_mask(u64 me_value, u64 me_mask) +{ + /* shadow_me_value must be a subset of shadow_me_mask */ + if (WARN_ON(me_value & ~me_mask)) + me_value = me_mask = 0; + + shadow_me_value = me_value; + shadow_me_mask = me_mask; +} +EXPORT_SYMBOL_GPL(kvm_mmu_set_me_spte_mask); + +void kvm_mmu_set_ept_masks(bool has_ad_bits, bool has_exec_only) +{ + shadow_user_mask = VMX_EPT_READABLE_MASK; + shadow_accessed_mask = has_ad_bits ? VMX_EPT_ACCESS_BIT : 0ull; + shadow_dirty_mask = has_ad_bits ? VMX_EPT_DIRTY_BIT : 0ull; + shadow_nx_mask = 0ull; + shadow_x_mask = VMX_EPT_EXECUTABLE_MASK; + shadow_present_mask = has_exec_only ? 0ull : VMX_EPT_READABLE_MASK; + /* + * EPT overrides the host MTRRs, and so KVM must program the desired + * memtype directly into the SPTEs. Note, this mask is just the mask + * of all bits that factor into the memtype, the actual memtype must be + * dynamically calculated, e.g. to ensure host MMIO is mapped UC. + */ + shadow_memtype_mask = VMX_EPT_MT_MASK | VMX_EPT_IPAT_BIT; + shadow_acc_track_mask = VMX_EPT_RWX_MASK; + shadow_host_writable_mask = EPT_SPTE_HOST_WRITABLE; + shadow_mmu_writable_mask = EPT_SPTE_MMU_WRITABLE; + + /* + * EPT Misconfigurations are generated if the value of bits 2:0 + * of an EPT paging-structure entry is 110b (write/execute). + */ + kvm_mmu_set_mmio_spte_mask(VMX_EPT_MISCONFIG_WX_VALUE, + VMX_EPT_RWX_MASK, 0); +} +EXPORT_SYMBOL_GPL(kvm_mmu_set_ept_masks); + +void kvm_mmu_reset_all_pte_masks(void) +{ + u8 low_phys_bits; + u64 mask; + + shadow_phys_bits = kvm_get_shadow_phys_bits(); + + /* + * If the CPU has 46 or less physical address bits, then set an + * appropriate mask to guard against L1TF attacks. Otherwise, it is + * assumed that the CPU is not vulnerable to L1TF. + * + * Some Intel CPUs address the L1 cache using more PA bits than are + * reported by CPUID. Use the PA width of the L1 cache when possible + * to achieve more effective mitigation, e.g. if system RAM overlaps + * the most significant bits of legal physical address space. + */ + shadow_nonpresent_or_rsvd_mask = 0; + low_phys_bits = boot_cpu_data.x86_phys_bits; + if (boot_cpu_has_bug(X86_BUG_L1TF) && + !WARN_ON_ONCE(boot_cpu_data.x86_cache_bits >= + 52 - SHADOW_NONPRESENT_OR_RSVD_MASK_LEN)) { + low_phys_bits = boot_cpu_data.x86_cache_bits + - SHADOW_NONPRESENT_OR_RSVD_MASK_LEN; + shadow_nonpresent_or_rsvd_mask = + rsvd_bits(low_phys_bits, boot_cpu_data.x86_cache_bits - 1); + } + + shadow_nonpresent_or_rsvd_lower_gfn_mask = + GENMASK_ULL(low_phys_bits - 1, PAGE_SHIFT); + + shadow_user_mask = PT_USER_MASK; + shadow_accessed_mask = PT_ACCESSED_MASK; + shadow_dirty_mask = PT_DIRTY_MASK; + shadow_nx_mask = PT64_NX_MASK; + shadow_x_mask = 0; + shadow_present_mask = PT_PRESENT_MASK; + + /* + * For shadow paging and NPT, KVM uses PAT entry '0' to encode WB + * memtype in the SPTEs, i.e. relies on host MTRRs to provide the + * correct memtype (WB is the "weakest" memtype). + */ + shadow_memtype_mask = 0; + shadow_acc_track_mask = 0; + shadow_me_mask = 0; + shadow_me_value = 0; + + shadow_host_writable_mask = DEFAULT_SPTE_HOST_WRITABLE; + shadow_mmu_writable_mask = DEFAULT_SPTE_MMU_WRITABLE; + + /* + * Set a reserved PA bit in MMIO SPTEs to generate page faults with + * PFEC.RSVD=1 on MMIO accesses. 64-bit PTEs (PAE, x86-64, and EPT + * paging) support a maximum of 52 bits of PA, i.e. if the CPU supports + * 52-bit physical addresses then there are no reserved PA bits in the + * PTEs and so the reserved PA approach must be disabled. + */ + if (shadow_phys_bits < 52) + mask = BIT_ULL(51) | PT_PRESENT_MASK; + else + mask = 0; + + kvm_mmu_set_mmio_spte_mask(mask, mask, ACC_WRITE_MASK | ACC_USER_MASK); +} diff --git a/arch/x86/kvm/mmu/spte.h b/arch/x86/kvm/mmu/spte.h new file mode 100644 index 000000000..7670c13ce --- /dev/null +++ b/arch/x86/kvm/mmu/spte.h @@ -0,0 +1,474 @@ +// SPDX-License-Identifier: GPL-2.0-only + +#ifndef KVM_X86_MMU_SPTE_H +#define KVM_X86_MMU_SPTE_H + +#include "mmu_internal.h" + +/* + * A MMU present SPTE is backed by actual memory and may or may not be present + * in hardware. E.g. MMIO SPTEs are not considered present. Use bit 11, as it + * is ignored by all flavors of SPTEs and checking a low bit often generates + * better code than for a high bit, e.g. 56+. MMU present checks are pervasive + * enough that the improved code generation is noticeable in KVM's footprint. + */ +#define SPTE_MMU_PRESENT_MASK BIT_ULL(11) + +/* + * TDP SPTES (more specifically, EPT SPTEs) may not have A/D bits, and may also + * be restricted to using write-protection (for L2 when CPU dirty logging, i.e. + * PML, is enabled). Use bits 52 and 53 to hold the type of A/D tracking that + * is must be employed for a given TDP SPTE. + * + * Note, the "enabled" mask must be '0', as bits 62:52 are _reserved_ for PAE + * paging, including NPT PAE. This scheme works because legacy shadow paging + * is guaranteed to have A/D bits and write-protection is forced only for + * TDP with CPU dirty logging (PML). If NPT ever gains PML-like support, it + * must be restricted to 64-bit KVM. + */ +#define SPTE_TDP_AD_SHIFT 52 +#define SPTE_TDP_AD_MASK (3ULL << SPTE_TDP_AD_SHIFT) +#define SPTE_TDP_AD_ENABLED_MASK (0ULL << SPTE_TDP_AD_SHIFT) +#define SPTE_TDP_AD_DISABLED_MASK (1ULL << SPTE_TDP_AD_SHIFT) +#define SPTE_TDP_AD_WRPROT_ONLY_MASK (2ULL << SPTE_TDP_AD_SHIFT) +static_assert(SPTE_TDP_AD_ENABLED_MASK == 0); + +#ifdef CONFIG_DYNAMIC_PHYSICAL_MASK +#define SPTE_BASE_ADDR_MASK (physical_mask & ~(u64)(PAGE_SIZE-1)) +#else +#define SPTE_BASE_ADDR_MASK (((1ULL << 52) - 1) & ~(u64)(PAGE_SIZE-1)) +#endif + +#define SPTE_PERM_MASK (PT_PRESENT_MASK | PT_WRITABLE_MASK | shadow_user_mask \ + | shadow_x_mask | shadow_nx_mask | shadow_me_mask) + +#define ACC_EXEC_MASK 1 +#define ACC_WRITE_MASK PT_WRITABLE_MASK +#define ACC_USER_MASK PT_USER_MASK +#define ACC_ALL (ACC_EXEC_MASK | ACC_WRITE_MASK | ACC_USER_MASK) + +/* The mask for the R/X bits in EPT PTEs */ +#define SPTE_EPT_READABLE_MASK 0x1ull +#define SPTE_EPT_EXECUTABLE_MASK 0x4ull + +#define SPTE_LEVEL_BITS 9 +#define SPTE_LEVEL_SHIFT(level) __PT_LEVEL_SHIFT(level, SPTE_LEVEL_BITS) +#define SPTE_INDEX(address, level) __PT_INDEX(address, level, SPTE_LEVEL_BITS) +#define SPTE_ENT_PER_PAGE __PT_ENT_PER_PAGE(SPTE_LEVEL_BITS) + +/* + * The mask/shift to use for saving the original R/X bits when marking the PTE + * as not-present for access tracking purposes. We do not save the W bit as the + * PTEs being access tracked also need to be dirty tracked, so the W bit will be + * restored only when a write is attempted to the page. This mask obviously + * must not overlap the A/D type mask. + */ +#define SHADOW_ACC_TRACK_SAVED_BITS_MASK (SPTE_EPT_READABLE_MASK | \ + SPTE_EPT_EXECUTABLE_MASK) +#define SHADOW_ACC_TRACK_SAVED_BITS_SHIFT 54 +#define SHADOW_ACC_TRACK_SAVED_MASK (SHADOW_ACC_TRACK_SAVED_BITS_MASK << \ + SHADOW_ACC_TRACK_SAVED_BITS_SHIFT) +static_assert(!(SPTE_TDP_AD_MASK & SHADOW_ACC_TRACK_SAVED_MASK)); + +/* + * {DEFAULT,EPT}_SPTE_{HOST,MMU}_WRITABLE are used to keep track of why a given + * SPTE is write-protected. See is_writable_pte() for details. + */ + +/* Bits 9 and 10 are ignored by all non-EPT PTEs. */ +#define DEFAULT_SPTE_HOST_WRITABLE BIT_ULL(9) +#define DEFAULT_SPTE_MMU_WRITABLE BIT_ULL(10) + +/* + * Low ignored bits are at a premium for EPT, use high ignored bits, taking care + * to not overlap the A/D type mask or the saved access bits of access-tracked + * SPTEs when A/D bits are disabled. + */ +#define EPT_SPTE_HOST_WRITABLE BIT_ULL(57) +#define EPT_SPTE_MMU_WRITABLE BIT_ULL(58) + +static_assert(!(EPT_SPTE_HOST_WRITABLE & SPTE_TDP_AD_MASK)); +static_assert(!(EPT_SPTE_MMU_WRITABLE & SPTE_TDP_AD_MASK)); +static_assert(!(EPT_SPTE_HOST_WRITABLE & SHADOW_ACC_TRACK_SAVED_MASK)); +static_assert(!(EPT_SPTE_MMU_WRITABLE & SHADOW_ACC_TRACK_SAVED_MASK)); + +/* Defined only to keep the above static asserts readable. */ +#undef SHADOW_ACC_TRACK_SAVED_MASK + +/* + * Due to limited space in PTEs, the MMIO generation is a 19 bit subset of + * the memslots generation and is derived as follows: + * + * Bits 0-7 of the MMIO generation are propagated to spte bits 3-10 + * Bits 8-18 of the MMIO generation are propagated to spte bits 52-62 + * + * The KVM_MEMSLOT_GEN_UPDATE_IN_PROGRESS flag is intentionally not included in + * the MMIO generation number, as doing so would require stealing a bit from + * the "real" generation number and thus effectively halve the maximum number + * of MMIO generations that can be handled before encountering a wrap (which + * requires a full MMU zap). The flag is instead explicitly queried when + * checking for MMIO spte cache hits. + */ + +#define MMIO_SPTE_GEN_LOW_START 3 +#define MMIO_SPTE_GEN_LOW_END 10 + +#define MMIO_SPTE_GEN_HIGH_START 52 +#define MMIO_SPTE_GEN_HIGH_END 62 + +#define MMIO_SPTE_GEN_LOW_MASK GENMASK_ULL(MMIO_SPTE_GEN_LOW_END, \ + MMIO_SPTE_GEN_LOW_START) +#define MMIO_SPTE_GEN_HIGH_MASK GENMASK_ULL(MMIO_SPTE_GEN_HIGH_END, \ + MMIO_SPTE_GEN_HIGH_START) +static_assert(!(SPTE_MMU_PRESENT_MASK & + (MMIO_SPTE_GEN_LOW_MASK | MMIO_SPTE_GEN_HIGH_MASK))); + +/* + * The SPTE MMIO mask must NOT overlap the MMIO generation bits or the + * MMU-present bit. The generation obviously co-exists with the magic MMIO + * mask/value, and MMIO SPTEs are considered !MMU-present. + * + * The SPTE MMIO mask is allowed to use hardware "present" bits (i.e. all EPT + * RWX bits), all physical address bits (legal PA bits are used for "fast" MMIO + * and so they're off-limits for generation; additional checks ensure the mask + * doesn't overlap legal PA bits), and bit 63 (carved out for future usage). + */ +#define SPTE_MMIO_ALLOWED_MASK (BIT_ULL(63) | GENMASK_ULL(51, 12) | GENMASK_ULL(2, 0)) +static_assert(!(SPTE_MMIO_ALLOWED_MASK & + (SPTE_MMU_PRESENT_MASK | MMIO_SPTE_GEN_LOW_MASK | MMIO_SPTE_GEN_HIGH_MASK))); + +#define MMIO_SPTE_GEN_LOW_BITS (MMIO_SPTE_GEN_LOW_END - MMIO_SPTE_GEN_LOW_START + 1) +#define MMIO_SPTE_GEN_HIGH_BITS (MMIO_SPTE_GEN_HIGH_END - MMIO_SPTE_GEN_HIGH_START + 1) + +/* remember to adjust the comment above as well if you change these */ +static_assert(MMIO_SPTE_GEN_LOW_BITS == 8 && MMIO_SPTE_GEN_HIGH_BITS == 11); + +#define MMIO_SPTE_GEN_LOW_SHIFT (MMIO_SPTE_GEN_LOW_START - 0) +#define MMIO_SPTE_GEN_HIGH_SHIFT (MMIO_SPTE_GEN_HIGH_START - MMIO_SPTE_GEN_LOW_BITS) + +#define MMIO_SPTE_GEN_MASK GENMASK_ULL(MMIO_SPTE_GEN_LOW_BITS + MMIO_SPTE_GEN_HIGH_BITS - 1, 0) + +extern u64 __read_mostly shadow_host_writable_mask; +extern u64 __read_mostly shadow_mmu_writable_mask; +extern u64 __read_mostly shadow_nx_mask; +extern u64 __read_mostly shadow_x_mask; /* mutual exclusive with nx_mask */ +extern u64 __read_mostly shadow_user_mask; +extern u64 __read_mostly shadow_accessed_mask; +extern u64 __read_mostly shadow_dirty_mask; +extern u64 __read_mostly shadow_mmio_value; +extern u64 __read_mostly shadow_mmio_mask; +extern u64 __read_mostly shadow_mmio_access_mask; +extern u64 __read_mostly shadow_present_mask; +extern u64 __read_mostly shadow_memtype_mask; +extern u64 __read_mostly shadow_me_value; +extern u64 __read_mostly shadow_me_mask; + +/* + * SPTEs in MMUs without A/D bits are marked with SPTE_TDP_AD_DISABLED_MASK; + * shadow_acc_track_mask is the set of bits to be cleared in non-accessed + * pages. + */ +extern u64 __read_mostly shadow_acc_track_mask; + +/* + * This mask must be set on all non-zero Non-Present or Reserved SPTEs in order + * to guard against L1TF attacks. + */ +extern u64 __read_mostly shadow_nonpresent_or_rsvd_mask; + +/* + * The number of high-order 1 bits to use in the mask above. + */ +#define SHADOW_NONPRESENT_OR_RSVD_MASK_LEN 5 + +/* + * If a thread running without exclusive control of the MMU lock must perform a + * multi-part operation on an SPTE, it can set the SPTE to REMOVED_SPTE as a + * non-present intermediate value. Other threads which encounter this value + * should not modify the SPTE. + * + * Use a semi-arbitrary value that doesn't set RWX bits, i.e. is not-present on + * bot AMD and Intel CPUs, and doesn't set PFN bits, i.e. doesn't create a L1TF + * vulnerability. Use only low bits to avoid 64-bit immediates. + * + * Only used by the TDP MMU. + */ +#define REMOVED_SPTE 0x5a0ULL + +/* Removed SPTEs must not be misconstrued as shadow present PTEs. */ +static_assert(!(REMOVED_SPTE & SPTE_MMU_PRESENT_MASK)); + +static inline bool is_removed_spte(u64 spte) +{ + return spte == REMOVED_SPTE; +} + +/* Get an SPTE's index into its parent's page table (and the spt array). */ +static inline int spte_index(u64 *sptep) +{ + return ((unsigned long)sptep / sizeof(*sptep)) & (SPTE_ENT_PER_PAGE - 1); +} + +/* + * In some cases, we need to preserve the GFN of a non-present or reserved + * SPTE when we usurp the upper five bits of the physical address space to + * defend against L1TF, e.g. for MMIO SPTEs. To preserve the GFN, we'll + * shift bits of the GFN that overlap with shadow_nonpresent_or_rsvd_mask + * left into the reserved bits, i.e. the GFN in the SPTE will be split into + * high and low parts. This mask covers the lower bits of the GFN. + */ +extern u64 __read_mostly shadow_nonpresent_or_rsvd_lower_gfn_mask; + +static inline bool is_mmio_spte(u64 spte) +{ + return (spte & shadow_mmio_mask) == shadow_mmio_value && + likely(enable_mmio_caching); +} + +static inline bool is_shadow_present_pte(u64 pte) +{ + return !!(pte & SPTE_MMU_PRESENT_MASK); +} + +/* + * Returns true if A/D bits are supported in hardware and are enabled by KVM. + * When enabled, KVM uses A/D bits for all non-nested MMUs. Because L1 can + * disable A/D bits in EPTP12, SP and SPTE variants are needed to handle the + * scenario where KVM is using A/D bits for L1, but not L2. + */ +static inline bool kvm_ad_enabled(void) +{ + return !!shadow_accessed_mask; +} + +static inline bool sp_ad_disabled(struct kvm_mmu_page *sp) +{ + return sp->role.ad_disabled; +} + +static inline bool spte_ad_enabled(u64 spte) +{ + MMU_WARN_ON(!is_shadow_present_pte(spte)); + return (spte & SPTE_TDP_AD_MASK) != SPTE_TDP_AD_DISABLED_MASK; +} + +static inline bool spte_ad_need_write_protect(u64 spte) +{ + MMU_WARN_ON(!is_shadow_present_pte(spte)); + /* + * This is benign for non-TDP SPTEs as SPTE_TDP_AD_ENABLED_MASK is '0', + * and non-TDP SPTEs will never set these bits. Optimize for 64-bit + * TDP and do the A/D type check unconditionally. + */ + return (spte & SPTE_TDP_AD_MASK) != SPTE_TDP_AD_ENABLED_MASK; +} + +static inline u64 spte_shadow_accessed_mask(u64 spte) +{ + MMU_WARN_ON(!is_shadow_present_pte(spte)); + return spte_ad_enabled(spte) ? shadow_accessed_mask : 0; +} + +static inline u64 spte_shadow_dirty_mask(u64 spte) +{ + MMU_WARN_ON(!is_shadow_present_pte(spte)); + return spte_ad_enabled(spte) ? shadow_dirty_mask : 0; +} + +static inline bool is_access_track_spte(u64 spte) +{ + return !spte_ad_enabled(spte) && (spte & shadow_acc_track_mask) == 0; +} + +static inline bool is_large_pte(u64 pte) +{ + return pte & PT_PAGE_SIZE_MASK; +} + +static inline bool is_last_spte(u64 pte, int level) +{ + return (level == PG_LEVEL_4K) || is_large_pte(pte); +} + +static inline bool is_executable_pte(u64 spte) +{ + return (spte & (shadow_x_mask | shadow_nx_mask)) == shadow_x_mask; +} + +static inline kvm_pfn_t spte_to_pfn(u64 pte) +{ + return (pte & SPTE_BASE_ADDR_MASK) >> PAGE_SHIFT; +} + +static inline bool is_accessed_spte(u64 spte) +{ + u64 accessed_mask = spte_shadow_accessed_mask(spte); + + return accessed_mask ? spte & accessed_mask + : !is_access_track_spte(spte); +} + +static inline bool is_dirty_spte(u64 spte) +{ + u64 dirty_mask = spte_shadow_dirty_mask(spte); + + return dirty_mask ? spte & dirty_mask : spte & PT_WRITABLE_MASK; +} + +static inline u64 get_rsvd_bits(struct rsvd_bits_validate *rsvd_check, u64 pte, + int level) +{ + int bit7 = (pte >> 7) & 1; + + return rsvd_check->rsvd_bits_mask[bit7][level-1]; +} + +static inline bool __is_rsvd_bits_set(struct rsvd_bits_validate *rsvd_check, + u64 pte, int level) +{ + return pte & get_rsvd_bits(rsvd_check, pte, level); +} + +static inline bool __is_bad_mt_xwr(struct rsvd_bits_validate *rsvd_check, + u64 pte) +{ + return rsvd_check->bad_mt_xwr & BIT_ULL(pte & 0x3f); +} + +static __always_inline bool is_rsvd_spte(struct rsvd_bits_validate *rsvd_check, + u64 spte, int level) +{ + return __is_bad_mt_xwr(rsvd_check, spte) || + __is_rsvd_bits_set(rsvd_check, spte, level); +} + +/* + * A shadow-present leaf SPTE may be non-writable for 4 possible reasons: + * + * 1. To intercept writes for dirty logging. KVM write-protects huge pages + * so that they can be split be split down into the dirty logging + * granularity (4KiB) whenever the guest writes to them. KVM also + * write-protects 4KiB pages so that writes can be recorded in the dirty log + * (e.g. if not using PML). SPTEs are write-protected for dirty logging + * during the VM-iotcls that enable dirty logging. + * + * 2. To intercept writes to guest page tables that KVM is shadowing. When a + * guest writes to its page table the corresponding shadow page table will + * be marked "unsync". That way KVM knows which shadow page tables need to + * be updated on the next TLB flush, INVLPG, etc. and which do not. + * + * 3. To prevent guest writes to read-only memory, such as for memory in a + * read-only memslot or guest memory backed by a read-only VMA. Writes to + * such pages are disallowed entirely. + * + * 4. To emulate the Accessed bit for SPTEs without A/D bits. Note, in this + * case, the SPTE is access-protected, not just write-protected! + * + * For cases #1 and #4, KVM can safely make such SPTEs writable without taking + * mmu_lock as capturing the Accessed/Dirty state doesn't require taking it. + * To differentiate #1 and #4 from #2 and #3, KVM uses two software-only bits + * in the SPTE: + * + * shadow_mmu_writable_mask, aka MMU-writable - + * Cleared on SPTEs that KVM is currently write-protecting for shadow paging + * purposes (case 2 above). + * + * shadow_host_writable_mask, aka Host-writable - + * Cleared on SPTEs that are not host-writable (case 3 above) + * + * Note, not all possible combinations of PT_WRITABLE_MASK, + * shadow_mmu_writable_mask, and shadow_host_writable_mask are valid. A given + * SPTE can be in only one of the following states, which map to the + * aforementioned 3 cases: + * + * shadow_host_writable_mask | shadow_mmu_writable_mask | PT_WRITABLE_MASK + * ------------------------- | ------------------------ | ---------------- + * 1 | 1 | 1 (writable) + * 1 | 1 | 0 (case 1) + * 1 | 0 | 0 (case 2) + * 0 | 0 | 0 (case 3) + * + * The valid combinations of these bits are checked by + * check_spte_writable_invariants() whenever an SPTE is modified. + * + * Clearing the MMU-writable bit is always done under the MMU lock and always + * accompanied by a TLB flush before dropping the lock to avoid corrupting the + * shadow page tables between vCPUs. Write-protecting an SPTE for dirty logging + * (which does not clear the MMU-writable bit), does not flush TLBs before + * dropping the lock, as it only needs to synchronize guest writes with the + * dirty bitmap. Similarly, making the SPTE inaccessible (and non-writable) for + * access-tracking via the clear_young() MMU notifier also does not flush TLBs. + * + * So, there is the problem: clearing the MMU-writable bit can encounter a + * write-protected SPTE while CPUs still have writable mappings for that SPTE + * cached in their TLB. To address this, KVM always flushes TLBs when + * write-protecting SPTEs if the MMU-writable bit is set on the old SPTE. + * + * The Host-writable bit is not modified on present SPTEs, it is only set or + * cleared when an SPTE is first faulted in from non-present and then remains + * immutable. + */ +static inline bool is_writable_pte(unsigned long pte) +{ + return pte & PT_WRITABLE_MASK; +} + +/* Note: spte must be a shadow-present leaf SPTE. */ +static inline void check_spte_writable_invariants(u64 spte) +{ + if (spte & shadow_mmu_writable_mask) + WARN_ONCE(!(spte & shadow_host_writable_mask), + "kvm: MMU-writable SPTE is not Host-writable: %llx", + spte); + else + WARN_ONCE(is_writable_pte(spte), + "kvm: Writable SPTE is not MMU-writable: %llx", spte); +} + +static inline bool is_mmu_writable_spte(u64 spte) +{ + return spte & shadow_mmu_writable_mask; +} + +static inline u64 get_mmio_spte_generation(u64 spte) +{ + u64 gen; + + gen = (spte & MMIO_SPTE_GEN_LOW_MASK) >> MMIO_SPTE_GEN_LOW_SHIFT; + gen |= (spte & MMIO_SPTE_GEN_HIGH_MASK) >> MMIO_SPTE_GEN_HIGH_SHIFT; + return gen; +} + +bool spte_has_volatile_bits(u64 spte); + +bool make_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, + const struct kvm_memory_slot *slot, + unsigned int pte_access, gfn_t gfn, kvm_pfn_t pfn, + u64 old_spte, bool prefetch, bool can_unsync, + bool host_writable, u64 *new_spte); +u64 make_huge_page_split_spte(struct kvm *kvm, u64 huge_spte, + union kvm_mmu_page_role role, int index); +u64 make_nonleaf_spte(u64 *child_pt, bool ad_disabled); +u64 make_mmio_spte(struct kvm_vcpu *vcpu, u64 gfn, unsigned int access); +u64 mark_spte_for_access_track(u64 spte); + +/* Restore an acc-track PTE back to a regular PTE */ +static inline u64 restore_acc_track_spte(u64 spte) +{ + u64 saved_bits = (spte >> SHADOW_ACC_TRACK_SAVED_BITS_SHIFT) + & SHADOW_ACC_TRACK_SAVED_BITS_MASK; + + spte &= ~shadow_acc_track_mask; + spte &= ~(SHADOW_ACC_TRACK_SAVED_BITS_MASK << + SHADOW_ACC_TRACK_SAVED_BITS_SHIFT); + spte |= saved_bits; + + return spte; +} + +u64 kvm_mmu_changed_pte_notifier_make_spte(u64 old_spte, kvm_pfn_t new_pfn); + +void __init kvm_mmu_spte_module_init(void); +void kvm_mmu_reset_all_pte_masks(void); + +#endif diff --git a/arch/x86/kvm/mmu/tdp_iter.c b/arch/x86/kvm/mmu/tdp_iter.c new file mode 100644 index 000000000..39b48e7d7 --- /dev/null +++ b/arch/x86/kvm/mmu/tdp_iter.c @@ -0,0 +1,180 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include "mmu_internal.h" +#include "tdp_iter.h" +#include "spte.h" + +/* + * Recalculates the pointer to the SPTE for the current GFN and level and + * reread the SPTE. + */ +static void tdp_iter_refresh_sptep(struct tdp_iter *iter) +{ + iter->sptep = iter->pt_path[iter->level - 1] + + SPTE_INDEX(iter->gfn << PAGE_SHIFT, iter->level); + iter->old_spte = kvm_tdp_mmu_read_spte(iter->sptep); +} + +static gfn_t round_gfn_for_level(gfn_t gfn, int level) +{ + return gfn & -KVM_PAGES_PER_HPAGE(level); +} + +/* + * Return the TDP iterator to the root PT and allow it to continue its + * traversal over the paging structure from there. + */ +void tdp_iter_restart(struct tdp_iter *iter) +{ + iter->yielded = false; + iter->yielded_gfn = iter->next_last_level_gfn; + iter->level = iter->root_level; + + iter->gfn = round_gfn_for_level(iter->next_last_level_gfn, iter->level); + tdp_iter_refresh_sptep(iter); + + iter->valid = true; +} + +/* + * Sets a TDP iterator to walk a pre-order traversal of the paging structure + * rooted at root_pt, starting with the walk to translate next_last_level_gfn. + */ +void tdp_iter_start(struct tdp_iter *iter, struct kvm_mmu_page *root, + int min_level, gfn_t next_last_level_gfn) +{ + int root_level = root->role.level; + + WARN_ON(root_level < 1); + WARN_ON(root_level > PT64_ROOT_MAX_LEVEL); + + iter->next_last_level_gfn = next_last_level_gfn; + iter->root_level = root_level; + iter->min_level = min_level; + iter->pt_path[iter->root_level - 1] = (tdp_ptep_t)root->spt; + iter->as_id = kvm_mmu_page_as_id(root); + + tdp_iter_restart(iter); +} + +/* + * Given an SPTE and its level, returns a pointer containing the host virtual + * address of the child page table referenced by the SPTE. Returns null if + * there is no such entry. + */ +tdp_ptep_t spte_to_child_pt(u64 spte, int level) +{ + /* + * There's no child entry if this entry isn't present or is a + * last-level entry. + */ + if (!is_shadow_present_pte(spte) || is_last_spte(spte, level)) + return NULL; + + return (tdp_ptep_t)__va(spte_to_pfn(spte) << PAGE_SHIFT); +} + +/* + * Steps down one level in the paging structure towards the goal GFN. Returns + * true if the iterator was able to step down a level, false otherwise. + */ +static bool try_step_down(struct tdp_iter *iter) +{ + tdp_ptep_t child_pt; + + if (iter->level == iter->min_level) + return false; + + /* + * Reread the SPTE before stepping down to avoid traversing into page + * tables that are no longer linked from this entry. + */ + iter->old_spte = kvm_tdp_mmu_read_spte(iter->sptep); + + child_pt = spte_to_child_pt(iter->old_spte, iter->level); + if (!child_pt) + return false; + + iter->level--; + iter->pt_path[iter->level - 1] = child_pt; + iter->gfn = round_gfn_for_level(iter->next_last_level_gfn, iter->level); + tdp_iter_refresh_sptep(iter); + + return true; +} + +/* + * Steps to the next entry in the current page table, at the current page table + * level. The next entry could point to a page backing guest memory or another + * page table, or it could be non-present. Returns true if the iterator was + * able to step to the next entry in the page table, false if the iterator was + * already at the end of the current page table. + */ +static bool try_step_side(struct tdp_iter *iter) +{ + /* + * Check if the iterator is already at the end of the current page + * table. + */ + if (SPTE_INDEX(iter->gfn << PAGE_SHIFT, iter->level) == + (SPTE_ENT_PER_PAGE - 1)) + return false; + + iter->gfn += KVM_PAGES_PER_HPAGE(iter->level); + iter->next_last_level_gfn = iter->gfn; + iter->sptep++; + iter->old_spte = kvm_tdp_mmu_read_spte(iter->sptep); + + return true; +} + +/* + * Tries to traverse back up a level in the paging structure so that the walk + * can continue from the next entry in the parent page table. Returns true on a + * successful step up, false if already in the root page. + */ +static bool try_step_up(struct tdp_iter *iter) +{ + if (iter->level == iter->root_level) + return false; + + iter->level++; + iter->gfn = round_gfn_for_level(iter->gfn, iter->level); + tdp_iter_refresh_sptep(iter); + + return true; +} + +/* + * Step to the next SPTE in a pre-order traversal of the paging structure. + * To get to the next SPTE, the iterator either steps down towards the goal + * GFN, if at a present, non-last-level SPTE, or over to a SPTE mapping a + * highter GFN. + * + * The basic algorithm is as follows: + * 1. If the current SPTE is a non-last-level SPTE, step down into the page + * table it points to. + * 2. If the iterator cannot step down, it will try to step to the next SPTE + * in the current page of the paging structure. + * 3. If the iterator cannot step to the next entry in the current page, it will + * try to step up to the parent paging structure page. In this case, that + * SPTE will have already been visited, and so the iterator must also step + * to the side again. + */ +void tdp_iter_next(struct tdp_iter *iter) +{ + if (iter->yielded) { + tdp_iter_restart(iter); + return; + } + + if (try_step_down(iter)) + return; + + do { + if (try_step_side(iter)) + return; + } while (try_step_up(iter)); + iter->valid = false; +} + diff --git a/arch/x86/kvm/mmu/tdp_iter.h b/arch/x86/kvm/mmu/tdp_iter.h new file mode 100644 index 000000000..f0af385c5 --- /dev/null +++ b/arch/x86/kvm/mmu/tdp_iter.h @@ -0,0 +1,118 @@ +// SPDX-License-Identifier: GPL-2.0 + +#ifndef __KVM_X86_MMU_TDP_ITER_H +#define __KVM_X86_MMU_TDP_ITER_H + +#include <linux/kvm_host.h> + +#include "mmu.h" +#include "spte.h" + +/* + * TDP MMU SPTEs are RCU protected to allow paging structures (non-leaf SPTEs) + * to be zapped while holding mmu_lock for read, and to allow TLB flushes to be + * batched without having to collect the list of zapped SPs. Flows that can + * remove SPs must service pending TLB flushes prior to dropping RCU protection. + */ +static inline u64 kvm_tdp_mmu_read_spte(tdp_ptep_t sptep) +{ + return READ_ONCE(*rcu_dereference(sptep)); +} + +static inline u64 kvm_tdp_mmu_write_spte_atomic(tdp_ptep_t sptep, u64 new_spte) +{ + return xchg(rcu_dereference(sptep), new_spte); +} + +static inline void __kvm_tdp_mmu_write_spte(tdp_ptep_t sptep, u64 new_spte) +{ + WRITE_ONCE(*rcu_dereference(sptep), new_spte); +} + +static inline u64 kvm_tdp_mmu_write_spte(tdp_ptep_t sptep, u64 old_spte, + u64 new_spte, int level) +{ + /* + * Atomically write the SPTE if it is a shadow-present, leaf SPTE with + * volatile bits, i.e. has bits that can be set outside of mmu_lock. + * The Writable bit can be set by KVM's fast page fault handler, and + * Accessed and Dirty bits can be set by the CPU. + * + * Note, non-leaf SPTEs do have Accessed bits and those bits are + * technically volatile, but KVM doesn't consume the Accessed bit of + * non-leaf SPTEs, i.e. KVM doesn't care if it clobbers the bit. This + * logic needs to be reassessed if KVM were to use non-leaf Accessed + * bits, e.g. to skip stepping down into child SPTEs when aging SPTEs. + */ + if (is_shadow_present_pte(old_spte) && is_last_spte(old_spte, level) && + spte_has_volatile_bits(old_spte)) + return kvm_tdp_mmu_write_spte_atomic(sptep, new_spte); + + __kvm_tdp_mmu_write_spte(sptep, new_spte); + return old_spte; +} + +/* + * A TDP iterator performs a pre-order walk over a TDP paging structure. + */ +struct tdp_iter { + /* + * The iterator will traverse the paging structure towards the mapping + * for this GFN. + */ + gfn_t next_last_level_gfn; + /* + * The next_last_level_gfn at the time when the thread last + * yielded. Only yielding when the next_last_level_gfn != + * yielded_gfn helps ensure forward progress. + */ + gfn_t yielded_gfn; + /* Pointers to the page tables traversed to reach the current SPTE */ + tdp_ptep_t pt_path[PT64_ROOT_MAX_LEVEL]; + /* A pointer to the current SPTE */ + tdp_ptep_t sptep; + /* The lowest GFN mapped by the current SPTE */ + gfn_t gfn; + /* The level of the root page given to the iterator */ + int root_level; + /* The lowest level the iterator should traverse to */ + int min_level; + /* The iterator's current level within the paging structure */ + int level; + /* The address space ID, i.e. SMM vs. regular. */ + int as_id; + /* A snapshot of the value at sptep */ + u64 old_spte; + /* + * Whether the iterator has a valid state. This will be false if the + * iterator walks off the end of the paging structure. + */ + bool valid; + /* + * True if KVM dropped mmu_lock and yielded in the middle of a walk, in + * which case tdp_iter_next() needs to restart the walk at the root + * level instead of advancing to the next entry. + */ + bool yielded; +}; + +/* + * Iterates over every SPTE mapping the GFN range [start, end) in a + * preorder traversal. + */ +#define for_each_tdp_pte_min_level(iter, root, min_level, start, end) \ + for (tdp_iter_start(&iter, root, min_level, start); \ + iter.valid && iter.gfn < end; \ + tdp_iter_next(&iter)) + +#define for_each_tdp_pte(iter, root, start, end) \ + for_each_tdp_pte_min_level(iter, root, PG_LEVEL_4K, start, end) + +tdp_ptep_t spte_to_child_pt(u64 pte, int level); + +void tdp_iter_start(struct tdp_iter *iter, struct kvm_mmu_page *root, + int min_level, gfn_t next_last_level_gfn); +void tdp_iter_next(struct tdp_iter *iter); +void tdp_iter_restart(struct tdp_iter *iter); + +#endif /* __KVM_X86_MMU_TDP_ITER_H */ diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c new file mode 100644 index 000000000..c3b0f9733 --- /dev/null +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -0,0 +1,1885 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include "mmu.h" +#include "mmu_internal.h" +#include "mmutrace.h" +#include "tdp_iter.h" +#include "tdp_mmu.h" +#include "spte.h" + +#include <asm/cmpxchg.h> +#include <trace/events/kvm.h> + +static bool __read_mostly tdp_mmu_enabled = true; +module_param_named(tdp_mmu, tdp_mmu_enabled, bool, 0644); + +/* Initializes the TDP MMU for the VM, if enabled. */ +void kvm_mmu_init_tdp_mmu(struct kvm *kvm) +{ + if (!tdp_enabled || !READ_ONCE(tdp_mmu_enabled)) + return; + + /* This should not be changed for the lifetime of the VM. */ + kvm->arch.tdp_mmu_enabled = true; + INIT_LIST_HEAD(&kvm->arch.tdp_mmu_roots); + spin_lock_init(&kvm->arch.tdp_mmu_pages_lock); + INIT_LIST_HEAD(&kvm->arch.tdp_mmu_pages); +} + +/* Arbitrarily returns true so that this may be used in if statements. */ +static __always_inline bool kvm_lockdep_assert_mmu_lock_held(struct kvm *kvm, + bool shared) +{ + if (shared) + lockdep_assert_held_read(&kvm->mmu_lock); + else + lockdep_assert_held_write(&kvm->mmu_lock); + + return true; +} + +void kvm_mmu_uninit_tdp_mmu(struct kvm *kvm) +{ + if (!kvm->arch.tdp_mmu_enabled) + return; + + /* + * Invalidate all roots, which besides the obvious, schedules all roots + * for zapping and thus puts the TDP MMU's reference to each root, i.e. + * ultimately frees all roots. + */ + kvm_tdp_mmu_invalidate_all_roots(kvm); + kvm_tdp_mmu_zap_invalidated_roots(kvm); + + WARN_ON(!list_empty(&kvm->arch.tdp_mmu_pages)); + WARN_ON(!list_empty(&kvm->arch.tdp_mmu_roots)); + + /* + * Ensure that all the outstanding RCU callbacks to free shadow pages + * can run before the VM is torn down. Putting the last reference to + * zapped roots will create new callbacks. + */ + rcu_barrier(); +} + +static void tdp_mmu_free_sp(struct kvm_mmu_page *sp) +{ + free_page((unsigned long)sp->spt); + kmem_cache_free(mmu_page_header_cache, sp); +} + +/* + * This is called through call_rcu in order to free TDP page table memory + * safely with respect to other kernel threads that may be operating on + * the memory. + * By only accessing TDP MMU page table memory in an RCU read critical + * section, and freeing it after a grace period, lockless access to that + * memory won't use it after it is freed. + */ +static void tdp_mmu_free_sp_rcu_callback(struct rcu_head *head) +{ + struct kvm_mmu_page *sp = container_of(head, struct kvm_mmu_page, + rcu_head); + + tdp_mmu_free_sp(sp); +} + +void kvm_tdp_mmu_put_root(struct kvm *kvm, struct kvm_mmu_page *root, + bool shared) +{ + kvm_lockdep_assert_mmu_lock_held(kvm, shared); + + if (!refcount_dec_and_test(&root->tdp_mmu_root_count)) + return; + + /* + * The TDP MMU itself holds a reference to each root until the root is + * explicitly invalidated, i.e. the final reference should be never be + * put for a valid root. + */ + KVM_BUG_ON(!is_tdp_mmu_page(root) || !root->role.invalid, kvm); + + spin_lock(&kvm->arch.tdp_mmu_pages_lock); + list_del_rcu(&root->link); + spin_unlock(&kvm->arch.tdp_mmu_pages_lock); + call_rcu(&root->rcu_head, tdp_mmu_free_sp_rcu_callback); +} + +/* + * Returns the next root after @prev_root (or the first root if @prev_root is + * NULL). A reference to the returned root is acquired, and the reference to + * @prev_root is released (the caller obviously must hold a reference to + * @prev_root if it's non-NULL). + * + * If @only_valid is true, invalid roots are skipped. + * + * Returns NULL if the end of tdp_mmu_roots was reached. + */ +static struct kvm_mmu_page *tdp_mmu_next_root(struct kvm *kvm, + struct kvm_mmu_page *prev_root, + bool shared, bool only_valid) +{ + struct kvm_mmu_page *next_root; + + rcu_read_lock(); + + if (prev_root) + next_root = list_next_or_null_rcu(&kvm->arch.tdp_mmu_roots, + &prev_root->link, + typeof(*prev_root), link); + else + next_root = list_first_or_null_rcu(&kvm->arch.tdp_mmu_roots, + typeof(*next_root), link); + + while (next_root) { + if ((!only_valid || !next_root->role.invalid) && + kvm_tdp_mmu_get_root(next_root)) + break; + + next_root = list_next_or_null_rcu(&kvm->arch.tdp_mmu_roots, + &next_root->link, typeof(*next_root), link); + } + + rcu_read_unlock(); + + if (prev_root) + kvm_tdp_mmu_put_root(kvm, prev_root, shared); + + return next_root; +} + +/* + * Note: this iterator gets and puts references to the roots it iterates over. + * This makes it safe to release the MMU lock and yield within the loop, but + * if exiting the loop early, the caller must drop the reference to the most + * recent root. (Unless keeping a live reference is desirable.) + * + * If shared is set, this function is operating under the MMU lock in read + * mode. In the unlikely event that this thread must free a root, the lock + * will be temporarily dropped and reacquired in write mode. + */ +#define __for_each_tdp_mmu_root_yield_safe(_kvm, _root, _as_id, _shared, _only_valid)\ + for (_root = tdp_mmu_next_root(_kvm, NULL, _shared, _only_valid); \ + _root; \ + _root = tdp_mmu_next_root(_kvm, _root, _shared, _only_valid)) \ + if (kvm_lockdep_assert_mmu_lock_held(_kvm, _shared) && \ + kvm_mmu_page_as_id(_root) != _as_id) { \ + } else + +#define for_each_valid_tdp_mmu_root_yield_safe(_kvm, _root, _as_id, _shared) \ + __for_each_tdp_mmu_root_yield_safe(_kvm, _root, _as_id, _shared, true) + +#define for_each_tdp_mmu_root_yield_safe(_kvm, _root, _shared) \ + for (_root = tdp_mmu_next_root(_kvm, NULL, _shared, false); \ + _root; \ + _root = tdp_mmu_next_root(_kvm, _root, _shared, false)) \ + if (!kvm_lockdep_assert_mmu_lock_held(_kvm, _shared)) { \ + } else + +/* + * Iterate over all TDP MMU roots. Requires that mmu_lock be held for write, + * the implication being that any flow that holds mmu_lock for read is + * inherently yield-friendly and should use the yield-safe variant above. + * Holding mmu_lock for write obviates the need for RCU protection as the list + * is guaranteed to be stable. + */ +#define for_each_tdp_mmu_root(_kvm, _root, _as_id) \ + list_for_each_entry(_root, &_kvm->arch.tdp_mmu_roots, link) \ + if (kvm_lockdep_assert_mmu_lock_held(_kvm, false) && \ + kvm_mmu_page_as_id(_root) != _as_id) { \ + } else + +static struct kvm_mmu_page *tdp_mmu_alloc_sp(struct kvm_vcpu *vcpu) +{ + struct kvm_mmu_page *sp; + + sp = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_page_header_cache); + sp->spt = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_shadow_page_cache); + + return sp; +} + +static void tdp_mmu_init_sp(struct kvm_mmu_page *sp, tdp_ptep_t sptep, + gfn_t gfn, union kvm_mmu_page_role role) +{ + set_page_private(virt_to_page(sp->spt), (unsigned long)sp); + + sp->role = role; + sp->gfn = gfn; + sp->ptep = sptep; + sp->tdp_mmu_page = true; + + trace_kvm_mmu_get_page(sp, true); +} + +static void tdp_mmu_init_child_sp(struct kvm_mmu_page *child_sp, + struct tdp_iter *iter) +{ + struct kvm_mmu_page *parent_sp; + union kvm_mmu_page_role role; + + parent_sp = sptep_to_sp(rcu_dereference(iter->sptep)); + + role = parent_sp->role; + role.level--; + + tdp_mmu_init_sp(child_sp, iter->sptep, iter->gfn, role); +} + +hpa_t kvm_tdp_mmu_get_vcpu_root_hpa(struct kvm_vcpu *vcpu) +{ + union kvm_mmu_page_role role = vcpu->arch.mmu->root_role; + struct kvm *kvm = vcpu->kvm; + struct kvm_mmu_page *root; + + lockdep_assert_held_write(&kvm->mmu_lock); + + /* + * Check for an existing root before allocating a new one. Note, the + * role check prevents consuming an invalid root. + */ + for_each_tdp_mmu_root(kvm, root, kvm_mmu_role_as_id(role)) { + if (root->role.word == role.word && + kvm_tdp_mmu_get_root(root)) + goto out; + } + + root = tdp_mmu_alloc_sp(vcpu); + tdp_mmu_init_sp(root, NULL, 0, role); + + /* + * TDP MMU roots are kept until they are explicitly invalidated, either + * by a memslot update or by the destruction of the VM. Initialize the + * refcount to two; one reference for the vCPU, and one reference for + * the TDP MMU itself, which is held until the root is invalidated and + * is ultimately put by kvm_tdp_mmu_zap_invalidated_roots(). + */ + refcount_set(&root->tdp_mmu_root_count, 2); + + spin_lock(&kvm->arch.tdp_mmu_pages_lock); + list_add_rcu(&root->link, &kvm->arch.tdp_mmu_roots); + spin_unlock(&kvm->arch.tdp_mmu_pages_lock); + +out: + return __pa(root->spt); +} + +static void handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn, + u64 old_spte, u64 new_spte, int level, + bool shared); + +static void handle_changed_spte_acc_track(u64 old_spte, u64 new_spte, int level) +{ + if (!is_shadow_present_pte(old_spte) || !is_last_spte(old_spte, level)) + return; + + if (is_accessed_spte(old_spte) && + (!is_shadow_present_pte(new_spte) || !is_accessed_spte(new_spte) || + spte_to_pfn(old_spte) != spte_to_pfn(new_spte))) + kvm_set_pfn_accessed(spte_to_pfn(old_spte)); +} + +static void handle_changed_spte_dirty_log(struct kvm *kvm, int as_id, gfn_t gfn, + u64 old_spte, u64 new_spte, int level) +{ + bool pfn_changed; + struct kvm_memory_slot *slot; + + if (level > PG_LEVEL_4K) + return; + + pfn_changed = spte_to_pfn(old_spte) != spte_to_pfn(new_spte); + + if ((!is_writable_pte(old_spte) || pfn_changed) && + is_writable_pte(new_spte)) { + slot = __gfn_to_memslot(__kvm_memslots(kvm, as_id), gfn); + mark_page_dirty_in_slot(kvm, slot, gfn); + } +} + +static void tdp_account_mmu_page(struct kvm *kvm, struct kvm_mmu_page *sp) +{ + kvm_account_pgtable_pages((void *)sp->spt, +1); +} + +static void tdp_unaccount_mmu_page(struct kvm *kvm, struct kvm_mmu_page *sp) +{ + kvm_account_pgtable_pages((void *)sp->spt, -1); +} + +/** + * tdp_mmu_unlink_sp() - Remove a shadow page from the list of used pages + * + * @kvm: kvm instance + * @sp: the page to be removed + * @shared: This operation may not be running under the exclusive use of + * the MMU lock and the operation must synchronize with other + * threads that might be adding or removing pages. + */ +static void tdp_mmu_unlink_sp(struct kvm *kvm, struct kvm_mmu_page *sp, + bool shared) +{ + tdp_unaccount_mmu_page(kvm, sp); + if (shared) + spin_lock(&kvm->arch.tdp_mmu_pages_lock); + else + lockdep_assert_held_write(&kvm->mmu_lock); + + list_del(&sp->link); + if (sp->lpage_disallowed) + unaccount_huge_nx_page(kvm, sp); + + if (shared) + spin_unlock(&kvm->arch.tdp_mmu_pages_lock); +} + +/** + * handle_removed_pt() - handle a page table removed from the TDP structure + * + * @kvm: kvm instance + * @pt: the page removed from the paging structure + * @shared: This operation may not be running under the exclusive use + * of the MMU lock and the operation must synchronize with other + * threads that might be modifying SPTEs. + * + * Given a page table that has been removed from the TDP paging structure, + * iterates through the page table to clear SPTEs and free child page tables. + * + * Note that pt is passed in as a tdp_ptep_t, but it does not need RCU + * protection. Since this thread removed it from the paging structure, + * this thread will be responsible for ensuring the page is freed. Hence the + * early rcu_dereferences in the function. + */ +static void handle_removed_pt(struct kvm *kvm, tdp_ptep_t pt, bool shared) +{ + struct kvm_mmu_page *sp = sptep_to_sp(rcu_dereference(pt)); + int level = sp->role.level; + gfn_t base_gfn = sp->gfn; + int i; + + trace_kvm_mmu_prepare_zap_page(sp); + + tdp_mmu_unlink_sp(kvm, sp, shared); + + for (i = 0; i < SPTE_ENT_PER_PAGE; i++) { + tdp_ptep_t sptep = pt + i; + gfn_t gfn = base_gfn + i * KVM_PAGES_PER_HPAGE(level); + u64 old_spte; + + if (shared) { + /* + * Set the SPTE to a nonpresent value that other + * threads will not overwrite. If the SPTE was + * already marked as removed then another thread + * handling a page fault could overwrite it, so + * set the SPTE until it is set from some other + * value to the removed SPTE value. + */ + for (;;) { + old_spte = kvm_tdp_mmu_write_spte_atomic(sptep, REMOVED_SPTE); + if (!is_removed_spte(old_spte)) + break; + cpu_relax(); + } + } else { + /* + * If the SPTE is not MMU-present, there is no backing + * page associated with the SPTE and so no side effects + * that need to be recorded, and exclusive ownership of + * mmu_lock ensures the SPTE can't be made present. + * Note, zapping MMIO SPTEs is also unnecessary as they + * are guarded by the memslots generation, not by being + * unreachable. + */ + old_spte = kvm_tdp_mmu_read_spte(sptep); + if (!is_shadow_present_pte(old_spte)) + continue; + + /* + * Use the common helper instead of a raw WRITE_ONCE as + * the SPTE needs to be updated atomically if it can be + * modified by a different vCPU outside of mmu_lock. + * Even though the parent SPTE is !PRESENT, the TLB + * hasn't yet been flushed, and both Intel and AMD + * document that A/D assists can use upper-level PxE + * entries that are cached in the TLB, i.e. the CPU can + * still access the page and mark it dirty. + * + * No retry is needed in the atomic update path as the + * sole concern is dropping a Dirty bit, i.e. no other + * task can zap/remove the SPTE as mmu_lock is held for + * write. Marking the SPTE as a removed SPTE is not + * strictly necessary for the same reason, but using + * the remove SPTE value keeps the shared/exclusive + * paths consistent and allows the handle_changed_spte() + * call below to hardcode the new value to REMOVED_SPTE. + * + * Note, even though dropping a Dirty bit is the only + * scenario where a non-atomic update could result in a + * functional bug, simply checking the Dirty bit isn't + * sufficient as a fast page fault could read the upper + * level SPTE before it is zapped, and then make this + * target SPTE writable, resume the guest, and set the + * Dirty bit between reading the SPTE above and writing + * it here. + */ + old_spte = kvm_tdp_mmu_write_spte(sptep, old_spte, + REMOVED_SPTE, level); + } + handle_changed_spte(kvm, kvm_mmu_page_as_id(sp), gfn, + old_spte, REMOVED_SPTE, level, shared); + } + + call_rcu(&sp->rcu_head, tdp_mmu_free_sp_rcu_callback); +} + +/** + * __handle_changed_spte - handle bookkeeping associated with an SPTE change + * @kvm: kvm instance + * @as_id: the address space of the paging structure the SPTE was a part of + * @gfn: the base GFN that was mapped by the SPTE + * @old_spte: The value of the SPTE before the change + * @new_spte: The value of the SPTE after the change + * @level: the level of the PT the SPTE is part of in the paging structure + * @shared: This operation may not be running under the exclusive use of + * the MMU lock and the operation must synchronize with other + * threads that might be modifying SPTEs. + * + * Handle bookkeeping that might result from the modification of a SPTE. + * This function must be called for all TDP SPTE modifications. + */ +static void __handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn, + u64 old_spte, u64 new_spte, int level, + bool shared) +{ + bool was_present = is_shadow_present_pte(old_spte); + bool is_present = is_shadow_present_pte(new_spte); + bool was_leaf = was_present && is_last_spte(old_spte, level); + bool is_leaf = is_present && is_last_spte(new_spte, level); + bool pfn_changed = spte_to_pfn(old_spte) != spte_to_pfn(new_spte); + + WARN_ON(level > PT64_ROOT_MAX_LEVEL); + WARN_ON(level < PG_LEVEL_4K); + WARN_ON(gfn & (KVM_PAGES_PER_HPAGE(level) - 1)); + + /* + * If this warning were to trigger it would indicate that there was a + * missing MMU notifier or a race with some notifier handler. + * A present, leaf SPTE should never be directly replaced with another + * present leaf SPTE pointing to a different PFN. A notifier handler + * should be zapping the SPTE before the main MM's page table is + * changed, or the SPTE should be zeroed, and the TLBs flushed by the + * thread before replacement. + */ + if (was_leaf && is_leaf && pfn_changed) { + pr_err("Invalid SPTE change: cannot replace a present leaf\n" + "SPTE with another present leaf SPTE mapping a\n" + "different PFN!\n" + "as_id: %d gfn: %llx old_spte: %llx new_spte: %llx level: %d", + as_id, gfn, old_spte, new_spte, level); + + /* + * Crash the host to prevent error propagation and guest data + * corruption. + */ + BUG(); + } + + if (old_spte == new_spte) + return; + + trace_kvm_tdp_mmu_spte_changed(as_id, gfn, level, old_spte, new_spte); + + if (is_leaf) + check_spte_writable_invariants(new_spte); + + /* + * The only times a SPTE should be changed from a non-present to + * non-present state is when an MMIO entry is installed/modified/ + * removed. In that case, there is nothing to do here. + */ + if (!was_present && !is_present) { + /* + * If this change does not involve a MMIO SPTE or removed SPTE, + * it is unexpected. Log the change, though it should not + * impact the guest since both the former and current SPTEs + * are nonpresent. + */ + if (WARN_ON(!is_mmio_spte(old_spte) && + !is_mmio_spte(new_spte) && + !is_removed_spte(new_spte))) + pr_err("Unexpected SPTE change! Nonpresent SPTEs\n" + "should not be replaced with another,\n" + "different nonpresent SPTE, unless one or both\n" + "are MMIO SPTEs, or the new SPTE is\n" + "a temporary removed SPTE.\n" + "as_id: %d gfn: %llx old_spte: %llx new_spte: %llx level: %d", + as_id, gfn, old_spte, new_spte, level); + return; + } + + if (is_leaf != was_leaf) + kvm_update_page_stats(kvm, level, is_leaf ? 1 : -1); + + if (was_leaf && is_dirty_spte(old_spte) && + (!is_present || !is_dirty_spte(new_spte) || pfn_changed)) + kvm_set_pfn_dirty(spte_to_pfn(old_spte)); + + /* + * Recursively handle child PTs if the change removed a subtree from + * the paging structure. Note the WARN on the PFN changing without the + * SPTE being converted to a hugepage (leaf) or being zapped. Shadow + * pages are kernel allocations and should never be migrated. + */ + if (was_present && !was_leaf && + (is_leaf || !is_present || WARN_ON_ONCE(pfn_changed))) + handle_removed_pt(kvm, spte_to_child_pt(old_spte, level), shared); +} + +static void handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn, + u64 old_spte, u64 new_spte, int level, + bool shared) +{ + __handle_changed_spte(kvm, as_id, gfn, old_spte, new_spte, level, + shared); + handle_changed_spte_acc_track(old_spte, new_spte, level); + handle_changed_spte_dirty_log(kvm, as_id, gfn, old_spte, + new_spte, level); +} + +/* + * tdp_mmu_set_spte_atomic - Set a TDP MMU SPTE atomically + * and handle the associated bookkeeping. Do not mark the page dirty + * in KVM's dirty bitmaps. + * + * If setting the SPTE fails because it has changed, iter->old_spte will be + * refreshed to the current value of the spte. + * + * @kvm: kvm instance + * @iter: a tdp_iter instance currently on the SPTE that should be set + * @new_spte: The value the SPTE should be set to + * Return: + * * 0 - If the SPTE was set. + * * -EBUSY - If the SPTE cannot be set. In this case this function will have + * no side-effects other than setting iter->old_spte to the last + * known value of the spte. + */ +static inline int tdp_mmu_set_spte_atomic(struct kvm *kvm, + struct tdp_iter *iter, + u64 new_spte) +{ + u64 *sptep = rcu_dereference(iter->sptep); + + /* + * The caller is responsible for ensuring the old SPTE is not a REMOVED + * SPTE. KVM should never attempt to zap or manipulate a REMOVED SPTE, + * and pre-checking before inserting a new SPTE is advantageous as it + * avoids unnecessary work. + */ + WARN_ON_ONCE(iter->yielded || is_removed_spte(iter->old_spte)); + + lockdep_assert_held_read(&kvm->mmu_lock); + + /* + * Note, fast_pf_fix_direct_spte() can also modify TDP MMU SPTEs and + * does not hold the mmu_lock. + */ + if (!try_cmpxchg64(sptep, &iter->old_spte, new_spte)) + return -EBUSY; + + __handle_changed_spte(kvm, iter->as_id, iter->gfn, iter->old_spte, + new_spte, iter->level, true); + handle_changed_spte_acc_track(iter->old_spte, new_spte, iter->level); + + return 0; +} + +static inline int tdp_mmu_zap_spte_atomic(struct kvm *kvm, + struct tdp_iter *iter) +{ + int ret; + + /* + * Freeze the SPTE by setting it to a special, + * non-present value. This will stop other threads from + * immediately installing a present entry in its place + * before the TLBs are flushed. + */ + ret = tdp_mmu_set_spte_atomic(kvm, iter, REMOVED_SPTE); + if (ret) + return ret; + + kvm_flush_remote_tlbs_with_address(kvm, iter->gfn, + KVM_PAGES_PER_HPAGE(iter->level)); + + /* + * No other thread can overwrite the removed SPTE as they must either + * wait on the MMU lock or use tdp_mmu_set_spte_atomic() which will not + * overwrite the special removed SPTE value. No bookkeeping is needed + * here since the SPTE is going from non-present to non-present. Use + * the raw write helper to avoid an unnecessary check on volatile bits. + */ + __kvm_tdp_mmu_write_spte(iter->sptep, 0); + + return 0; +} + + +/* + * __tdp_mmu_set_spte - Set a TDP MMU SPTE and handle the associated bookkeeping + * @kvm: KVM instance + * @as_id: Address space ID, i.e. regular vs. SMM + * @sptep: Pointer to the SPTE + * @old_spte: The current value of the SPTE + * @new_spte: The new value that will be set for the SPTE + * @gfn: The base GFN that was (or will be) mapped by the SPTE + * @level: The level _containing_ the SPTE (its parent PT's level) + * @record_acc_track: Notify the MM subsystem of changes to the accessed state + * of the page. Should be set unless handling an MMU + * notifier for access tracking. Leaving record_acc_track + * unset in that case prevents page accesses from being + * double counted. + * @record_dirty_log: Record the page as dirty in the dirty bitmap if + * appropriate for the change being made. Should be set + * unless performing certain dirty logging operations. + * Leaving record_dirty_log unset in that case prevents page + * writes from being double counted. + * + * Returns the old SPTE value, which _may_ be different than @old_spte if the + * SPTE had voldatile bits. + */ +static u64 __tdp_mmu_set_spte(struct kvm *kvm, int as_id, tdp_ptep_t sptep, + u64 old_spte, u64 new_spte, gfn_t gfn, int level, + bool record_acc_track, bool record_dirty_log) +{ + lockdep_assert_held_write(&kvm->mmu_lock); + + /* + * No thread should be using this function to set SPTEs to or from the + * temporary removed SPTE value. + * If operating under the MMU lock in read mode, tdp_mmu_set_spte_atomic + * should be used. If operating under the MMU lock in write mode, the + * use of the removed SPTE should not be necessary. + */ + WARN_ON(is_removed_spte(old_spte) || is_removed_spte(new_spte)); + + old_spte = kvm_tdp_mmu_write_spte(sptep, old_spte, new_spte, level); + + __handle_changed_spte(kvm, as_id, gfn, old_spte, new_spte, level, false); + + if (record_acc_track) + handle_changed_spte_acc_track(old_spte, new_spte, level); + if (record_dirty_log) + handle_changed_spte_dirty_log(kvm, as_id, gfn, old_spte, + new_spte, level); + return old_spte; +} + +static inline void _tdp_mmu_set_spte(struct kvm *kvm, struct tdp_iter *iter, + u64 new_spte, bool record_acc_track, + bool record_dirty_log) +{ + WARN_ON_ONCE(iter->yielded); + + iter->old_spte = __tdp_mmu_set_spte(kvm, iter->as_id, iter->sptep, + iter->old_spte, new_spte, + iter->gfn, iter->level, + record_acc_track, record_dirty_log); +} + +static inline void tdp_mmu_set_spte(struct kvm *kvm, struct tdp_iter *iter, + u64 new_spte) +{ + _tdp_mmu_set_spte(kvm, iter, new_spte, true, true); +} + +static inline void tdp_mmu_set_spte_no_acc_track(struct kvm *kvm, + struct tdp_iter *iter, + u64 new_spte) +{ + _tdp_mmu_set_spte(kvm, iter, new_spte, false, true); +} + +static inline void tdp_mmu_set_spte_no_dirty_log(struct kvm *kvm, + struct tdp_iter *iter, + u64 new_spte) +{ + _tdp_mmu_set_spte(kvm, iter, new_spte, true, false); +} + +#define tdp_root_for_each_pte(_iter, _root, _start, _end) \ + for_each_tdp_pte(_iter, _root, _start, _end) + +#define tdp_root_for_each_leaf_pte(_iter, _root, _start, _end) \ + tdp_root_for_each_pte(_iter, _root, _start, _end) \ + if (!is_shadow_present_pte(_iter.old_spte) || \ + !is_last_spte(_iter.old_spte, _iter.level)) \ + continue; \ + else + +#define tdp_mmu_for_each_pte(_iter, _mmu, _start, _end) \ + for_each_tdp_pte(_iter, to_shadow_page(_mmu->root.hpa), _start, _end) + +/* + * Yield if the MMU lock is contended or this thread needs to return control + * to the scheduler. + * + * If this function should yield and flush is set, it will perform a remote + * TLB flush before yielding. + * + * If this function yields, iter->yielded is set and the caller must skip to + * the next iteration, where tdp_iter_next() will reset the tdp_iter's walk + * over the paging structures to allow the iterator to continue its traversal + * from the paging structure root. + * + * Returns true if this function yielded. + */ +static inline bool __must_check tdp_mmu_iter_cond_resched(struct kvm *kvm, + struct tdp_iter *iter, + bool flush, bool shared) +{ + WARN_ON(iter->yielded); + + /* Ensure forward progress has been made before yielding. */ + if (iter->next_last_level_gfn == iter->yielded_gfn) + return false; + + if (need_resched() || rwlock_needbreak(&kvm->mmu_lock)) { + if (flush) + kvm_flush_remote_tlbs(kvm); + + rcu_read_unlock(); + + if (shared) + cond_resched_rwlock_read(&kvm->mmu_lock); + else + cond_resched_rwlock_write(&kvm->mmu_lock); + + rcu_read_lock(); + + WARN_ON(iter->gfn > iter->next_last_level_gfn); + + iter->yielded = true; + } + + return iter->yielded; +} + +static inline gfn_t tdp_mmu_max_gfn_exclusive(void) +{ + /* + * Bound TDP MMU walks at host.MAXPHYADDR. KVM disallows memslots with + * a gpa range that would exceed the max gfn, and KVM does not create + * MMIO SPTEs for "impossible" gfns, instead sending such accesses down + * the slow emulation path every time. + */ + return kvm_mmu_max_gfn() + 1; +} + +static void __tdp_mmu_zap_root(struct kvm *kvm, struct kvm_mmu_page *root, + bool shared, int zap_level) +{ + struct tdp_iter iter; + + gfn_t end = tdp_mmu_max_gfn_exclusive(); + gfn_t start = 0; + + for_each_tdp_pte_min_level(iter, root, zap_level, start, end) { +retry: + if (tdp_mmu_iter_cond_resched(kvm, &iter, false, shared)) + continue; + + if (!is_shadow_present_pte(iter.old_spte)) + continue; + + if (iter.level > zap_level) + continue; + + if (!shared) + tdp_mmu_set_spte(kvm, &iter, 0); + else if (tdp_mmu_set_spte_atomic(kvm, &iter, 0)) + goto retry; + } +} + +static void tdp_mmu_zap_root(struct kvm *kvm, struct kvm_mmu_page *root, + bool shared) +{ + + /* + * The root must have an elevated refcount so that it's reachable via + * mmu_notifier callbacks, which allows this path to yield and drop + * mmu_lock. When handling an unmap/release mmu_notifier command, KVM + * must drop all references to relevant pages prior to completing the + * callback. Dropping mmu_lock with an unreachable root would result + * in zapping SPTEs after a relevant mmu_notifier callback completes + * and lead to use-after-free as zapping a SPTE triggers "writeback" of + * dirty accessed bits to the SPTE's associated struct page. + */ + WARN_ON_ONCE(!refcount_read(&root->tdp_mmu_root_count)); + + kvm_lockdep_assert_mmu_lock_held(kvm, shared); + + rcu_read_lock(); + + /* + * To avoid RCU stalls due to recursively removing huge swaths of SPs, + * split the zap into two passes. On the first pass, zap at the 1gb + * level, and then zap top-level SPs on the second pass. "1gb" is not + * arbitrary, as KVM must be able to zap a 1gb shadow page without + * inducing a stall to allow in-place replacement with a 1gb hugepage. + * + * Because zapping a SP recurses on its children, stepping down to + * PG_LEVEL_4K in the iterator itself is unnecessary. + */ + __tdp_mmu_zap_root(kvm, root, shared, PG_LEVEL_1G); + __tdp_mmu_zap_root(kvm, root, shared, root->role.level); + + rcu_read_unlock(); +} + +bool kvm_tdp_mmu_zap_sp(struct kvm *kvm, struct kvm_mmu_page *sp) +{ + u64 old_spte; + + /* + * This helper intentionally doesn't allow zapping a root shadow page, + * which doesn't have a parent page table and thus no associated entry. + */ + if (WARN_ON_ONCE(!sp->ptep)) + return false; + + old_spte = kvm_tdp_mmu_read_spte(sp->ptep); + if (WARN_ON_ONCE(!is_shadow_present_pte(old_spte))) + return false; + + __tdp_mmu_set_spte(kvm, kvm_mmu_page_as_id(sp), sp->ptep, old_spte, 0, + sp->gfn, sp->role.level + 1, true, true); + + return true; +} + +/* + * If can_yield is true, will release the MMU lock and reschedule if the + * scheduler needs the CPU or there is contention on the MMU lock. If this + * function cannot yield, it will not release the MMU lock or reschedule and + * the caller must ensure it does not supply too large a GFN range, or the + * operation can cause a soft lockup. + */ +static bool tdp_mmu_zap_leafs(struct kvm *kvm, struct kvm_mmu_page *root, + gfn_t start, gfn_t end, bool can_yield, bool flush) +{ + struct tdp_iter iter; + + end = min(end, tdp_mmu_max_gfn_exclusive()); + + lockdep_assert_held_write(&kvm->mmu_lock); + + rcu_read_lock(); + + for_each_tdp_pte_min_level(iter, root, PG_LEVEL_4K, start, end) { + if (can_yield && + tdp_mmu_iter_cond_resched(kvm, &iter, flush, false)) { + flush = false; + continue; + } + + if (!is_shadow_present_pte(iter.old_spte) || + !is_last_spte(iter.old_spte, iter.level)) + continue; + + tdp_mmu_set_spte(kvm, &iter, 0); + flush = true; + } + + rcu_read_unlock(); + + /* + * Because this flow zaps _only_ leaf SPTEs, the caller doesn't need + * to provide RCU protection as no 'struct kvm_mmu_page' will be freed. + */ + return flush; +} + +/* + * Zap leaf SPTEs for the range of gfns, [start, end), for all roots. Returns + * true if a TLB flush is needed before releasing the MMU lock, i.e. if one or + * more SPTEs were zapped since the MMU lock was last acquired. + */ +bool kvm_tdp_mmu_zap_leafs(struct kvm *kvm, gfn_t start, gfn_t end, bool flush) +{ + struct kvm_mmu_page *root; + + for_each_tdp_mmu_root_yield_safe(kvm, root, false) + flush = tdp_mmu_zap_leafs(kvm, root, start, end, true, flush); + + return flush; +} + +void kvm_tdp_mmu_zap_all(struct kvm *kvm) +{ + struct kvm_mmu_page *root; + + /* + * Zap all roots, including invalid roots, as all SPTEs must be dropped + * before returning to the caller. Zap directly even if the root is + * also being zapped by a worker. Walking zapped top-level SPTEs isn't + * all that expensive and mmu_lock is already held, which means the + * worker has yielded, i.e. flushing the work instead of zapping here + * isn't guaranteed to be any faster. + * + * A TLB flush is unnecessary, KVM zaps everything if and only the VM + * is being destroyed or the userspace VMM has exited. In both cases, + * KVM_RUN is unreachable, i.e. no vCPUs will ever service the request. + */ + for_each_tdp_mmu_root_yield_safe(kvm, root, false) + tdp_mmu_zap_root(kvm, root, false); +} + +/* + * Zap all invalidated roots to ensure all SPTEs are dropped before the "fast + * zap" completes. + */ +void kvm_tdp_mmu_zap_invalidated_roots(struct kvm *kvm) +{ + struct kvm_mmu_page *root; + + read_lock(&kvm->mmu_lock); + + for_each_tdp_mmu_root_yield_safe(kvm, root, true) { + if (!root->tdp_mmu_scheduled_root_to_zap) + continue; + + root->tdp_mmu_scheduled_root_to_zap = false; + KVM_BUG_ON(!root->role.invalid, kvm); + + /* + * A TLB flush is not necessary as KVM performs a local TLB + * flush when allocating a new root (see kvm_mmu_load()), and + * when migrating a vCPU to a different pCPU. Note, the local + * TLB flush on reuse also invalidates paging-structure-cache + * entries, i.e. TLB entries for intermediate paging structures, + * that may be zapped, as such entries are associated with the + * ASID on both VMX and SVM. + */ + tdp_mmu_zap_root(kvm, root, true); + + /* + * The referenced needs to be put *after* zapping the root, as + * the root must be reachable by mmu_notifiers while it's being + * zapped + */ + kvm_tdp_mmu_put_root(kvm, root, true); + } + + read_unlock(&kvm->mmu_lock); +} + +/* + * Mark each TDP MMU root as invalid to prevent vCPUs from reusing a root that + * is about to be zapped, e.g. in response to a memslots update. The actual + * zapping is done separately so that it happens with mmu_lock with read, + * whereas invalidating roots must be done with mmu_lock held for write (unless + * the VM is being destroyed). + * + * Note, kvm_tdp_mmu_zap_invalidated_roots() is gifted the TDP MMU's reference. + * See kvm_tdp_mmu_get_vcpu_root_hpa(). + */ +void kvm_tdp_mmu_invalidate_all_roots(struct kvm *kvm) +{ + struct kvm_mmu_page *root; + + /* + * mmu_lock must be held for write to ensure that a root doesn't become + * invalid while there are active readers (invalidating a root while + * there are active readers may or may not be problematic in practice, + * but it's uncharted territory and not supported). + * + * Waive the assertion if there are no users of @kvm, i.e. the VM is + * being destroyed after all references have been put, or if no vCPUs + * have been created (which means there are no roots), i.e. the VM is + * being destroyed in an error path of KVM_CREATE_VM. + */ + if (IS_ENABLED(CONFIG_PROVE_LOCKING) && + refcount_read(&kvm->users_count) && kvm->created_vcpus) + lockdep_assert_held_write(&kvm->mmu_lock); + + /* + * As above, mmu_lock isn't held when destroying the VM! There can't + * be other references to @kvm, i.e. nothing else can invalidate roots + * or get/put references to roots. + */ + list_for_each_entry(root, &kvm->arch.tdp_mmu_roots, link) { + /* + * Note, invalid roots can outlive a memslot update! Invalid + * roots must be *zapped* before the memslot update completes, + * but a different task can acquire a reference and keep the + * root alive after its been zapped. + */ + if (!root->role.invalid) { + root->tdp_mmu_scheduled_root_to_zap = true; + root->role.invalid = true; + } + } +} + +/* + * Installs a last-level SPTE to handle a TDP page fault. + * (NPT/EPT violation/misconfiguration) + */ +static int tdp_mmu_map_handle_target_level(struct kvm_vcpu *vcpu, + struct kvm_page_fault *fault, + struct tdp_iter *iter) +{ + struct kvm_mmu_page *sp = sptep_to_sp(rcu_dereference(iter->sptep)); + u64 new_spte; + int ret = RET_PF_FIXED; + bool wrprot = false; + + WARN_ON(sp->role.level != fault->goal_level); + if (unlikely(!fault->slot)) + new_spte = make_mmio_spte(vcpu, iter->gfn, ACC_ALL); + else + wrprot = make_spte(vcpu, sp, fault->slot, ACC_ALL, iter->gfn, + fault->pfn, iter->old_spte, fault->prefetch, true, + fault->map_writable, &new_spte); + + if (new_spte == iter->old_spte) + ret = RET_PF_SPURIOUS; + else if (tdp_mmu_set_spte_atomic(vcpu->kvm, iter, new_spte)) + return RET_PF_RETRY; + else if (is_shadow_present_pte(iter->old_spte) && + !is_last_spte(iter->old_spte, iter->level)) + kvm_flush_remote_tlbs_with_address(vcpu->kvm, sp->gfn, + KVM_PAGES_PER_HPAGE(iter->level + 1)); + + /* + * If the page fault was caused by a write but the page is write + * protected, emulation is needed. If the emulation was skipped, + * the vCPU would have the same fault again. + */ + if (wrprot) { + if (fault->write) + ret = RET_PF_EMULATE; + } + + /* If a MMIO SPTE is installed, the MMIO will need to be emulated. */ + if (unlikely(is_mmio_spte(new_spte))) { + vcpu->stat.pf_mmio_spte_created++; + trace_mark_mmio_spte(rcu_dereference(iter->sptep), iter->gfn, + new_spte); + ret = RET_PF_EMULATE; + } else { + trace_kvm_mmu_set_spte(iter->level, iter->gfn, + rcu_dereference(iter->sptep)); + } + + return ret; +} + +/* + * tdp_mmu_link_sp - Replace the given spte with an spte pointing to the + * provided page table. + * + * @kvm: kvm instance + * @iter: a tdp_iter instance currently on the SPTE that should be set + * @sp: The new TDP page table to install. + * @account_nx: True if this page table is being installed to split a + * non-executable huge page. + * @shared: This operation is running under the MMU lock in read mode. + * + * Returns: 0 if the new page table was installed. Non-0 if the page table + * could not be installed (e.g. the atomic compare-exchange failed). + */ +static int tdp_mmu_link_sp(struct kvm *kvm, struct tdp_iter *iter, + struct kvm_mmu_page *sp, bool account_nx, + bool shared) +{ + u64 spte = make_nonleaf_spte(sp->spt, !kvm_ad_enabled()); + int ret = 0; + + if (shared) { + ret = tdp_mmu_set_spte_atomic(kvm, iter, spte); + if (ret) + return ret; + } else { + tdp_mmu_set_spte(kvm, iter, spte); + } + + spin_lock(&kvm->arch.tdp_mmu_pages_lock); + list_add(&sp->link, &kvm->arch.tdp_mmu_pages); + if (account_nx) + account_huge_nx_page(kvm, sp); + spin_unlock(&kvm->arch.tdp_mmu_pages_lock); + tdp_account_mmu_page(kvm, sp); + + return 0; +} + +/* + * Handle a TDP page fault (NPT/EPT violation/misconfiguration) by installing + * page tables and SPTEs to translate the faulting guest physical address. + */ +int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) +{ + struct kvm_mmu *mmu = vcpu->arch.mmu; + struct tdp_iter iter; + struct kvm_mmu_page *sp; + int ret; + + kvm_mmu_hugepage_adjust(vcpu, fault); + + trace_kvm_mmu_spte_requested(fault); + + rcu_read_lock(); + + tdp_mmu_for_each_pte(iter, mmu, fault->gfn, fault->gfn + 1) { + if (fault->nx_huge_page_workaround_enabled) + disallowed_hugepage_adjust(fault, iter.old_spte, iter.level); + + if (iter.level == fault->goal_level) + break; + + /* + * If there is an SPTE mapping a large page at a higher level + * than the target, that SPTE must be cleared and replaced + * with a non-leaf SPTE. + */ + if (is_shadow_present_pte(iter.old_spte) && + is_large_pte(iter.old_spte)) { + if (tdp_mmu_zap_spte_atomic(vcpu->kvm, &iter)) + break; + + /* + * The iter must explicitly re-read the spte here + * because the new value informs the !present + * path below. + */ + iter.old_spte = kvm_tdp_mmu_read_spte(iter.sptep); + } + + if (!is_shadow_present_pte(iter.old_spte)) { + bool account_nx = fault->huge_page_disallowed && + fault->req_level >= iter.level; + + /* + * If SPTE has been frozen by another thread, just + * give up and retry, avoiding unnecessary page table + * allocation and free. + */ + if (is_removed_spte(iter.old_spte)) + break; + + sp = tdp_mmu_alloc_sp(vcpu); + tdp_mmu_init_child_sp(sp, &iter); + + if (tdp_mmu_link_sp(vcpu->kvm, &iter, sp, account_nx, true)) { + tdp_mmu_free_sp(sp); + break; + } + } + } + + /* + * Force the guest to retry the access if the upper level SPTEs aren't + * in place, or if the target leaf SPTE is frozen by another CPU. + */ + if (iter.level != fault->goal_level || is_removed_spte(iter.old_spte)) { + rcu_read_unlock(); + return RET_PF_RETRY; + } + + ret = tdp_mmu_map_handle_target_level(vcpu, fault, &iter); + rcu_read_unlock(); + + return ret; +} + +bool kvm_tdp_mmu_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range, + bool flush) +{ + struct kvm_mmu_page *root; + + __for_each_tdp_mmu_root_yield_safe(kvm, root, range->slot->as_id, false, false) + flush = tdp_mmu_zap_leafs(kvm, root, range->start, range->end, + range->may_block, flush); + + return flush; +} + +typedef bool (*tdp_handler_t)(struct kvm *kvm, struct tdp_iter *iter, + struct kvm_gfn_range *range); + +static __always_inline bool kvm_tdp_mmu_handle_gfn(struct kvm *kvm, + struct kvm_gfn_range *range, + tdp_handler_t handler) +{ + struct kvm_mmu_page *root; + struct tdp_iter iter; + bool ret = false; + + /* + * Don't support rescheduling, none of the MMU notifiers that funnel + * into this helper allow blocking; it'd be dead, wasteful code. + */ + for_each_tdp_mmu_root(kvm, root, range->slot->as_id) { + rcu_read_lock(); + + tdp_root_for_each_leaf_pte(iter, root, range->start, range->end) + ret |= handler(kvm, &iter, range); + + rcu_read_unlock(); + } + + return ret; +} + +/* + * Mark the SPTEs range of GFNs [start, end) unaccessed and return non-zero + * if any of the GFNs in the range have been accessed. + */ +static bool age_gfn_range(struct kvm *kvm, struct tdp_iter *iter, + struct kvm_gfn_range *range) +{ + u64 new_spte = 0; + + /* If we have a non-accessed entry we don't need to change the pte. */ + if (!is_accessed_spte(iter->old_spte)) + return false; + + new_spte = iter->old_spte; + + if (spte_ad_enabled(new_spte)) { + new_spte &= ~shadow_accessed_mask; + } else { + /* + * Capture the dirty status of the page, so that it doesn't get + * lost when the SPTE is marked for access tracking. + */ + if (is_writable_pte(new_spte)) + kvm_set_pfn_dirty(spte_to_pfn(new_spte)); + + new_spte = mark_spte_for_access_track(new_spte); + } + + tdp_mmu_set_spte_no_acc_track(kvm, iter, new_spte); + + return true; +} + +bool kvm_tdp_mmu_age_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range) +{ + return kvm_tdp_mmu_handle_gfn(kvm, range, age_gfn_range); +} + +static bool test_age_gfn(struct kvm *kvm, struct tdp_iter *iter, + struct kvm_gfn_range *range) +{ + return is_accessed_spte(iter->old_spte); +} + +bool kvm_tdp_mmu_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range) +{ + return kvm_tdp_mmu_handle_gfn(kvm, range, test_age_gfn); +} + +static bool set_spte_gfn(struct kvm *kvm, struct tdp_iter *iter, + struct kvm_gfn_range *range) +{ + u64 new_spte; + + /* Huge pages aren't expected to be modified without first being zapped. */ + WARN_ON(pte_huge(range->pte) || range->start + 1 != range->end); + + if (iter->level != PG_LEVEL_4K || + !is_shadow_present_pte(iter->old_spte)) + return false; + + /* + * Note, when changing a read-only SPTE, it's not strictly necessary to + * zero the SPTE before setting the new PFN, but doing so preserves the + * invariant that the PFN of a present * leaf SPTE can never change. + * See __handle_changed_spte(). + */ + tdp_mmu_set_spte(kvm, iter, 0); + + if (!pte_write(range->pte)) { + new_spte = kvm_mmu_changed_pte_notifier_make_spte(iter->old_spte, + pte_pfn(range->pte)); + + tdp_mmu_set_spte(kvm, iter, new_spte); + } + + return true; +} + +/* + * Handle the changed_pte MMU notifier for the TDP MMU. + * data is a pointer to the new pte_t mapping the HVA specified by the MMU + * notifier. + * Returns non-zero if a flush is needed before releasing the MMU lock. + */ +bool kvm_tdp_mmu_set_spte_gfn(struct kvm *kvm, struct kvm_gfn_range *range) +{ + /* + * No need to handle the remote TLB flush under RCU protection, the + * target SPTE _must_ be a leaf SPTE, i.e. cannot result in freeing a + * shadow page. See the WARN on pfn_changed in __handle_changed_spte(). + */ + return kvm_tdp_mmu_handle_gfn(kvm, range, set_spte_gfn); +} + +/* + * Remove write access from all SPTEs at or above min_level that map GFNs + * [start, end). Returns true if an SPTE has been changed and the TLBs need to + * be flushed. + */ +static bool wrprot_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root, + gfn_t start, gfn_t end, int min_level) +{ + struct tdp_iter iter; + u64 new_spte; + bool spte_set = false; + + rcu_read_lock(); + + BUG_ON(min_level > KVM_MAX_HUGEPAGE_LEVEL); + + for_each_tdp_pte_min_level(iter, root, min_level, start, end) { +retry: + if (tdp_mmu_iter_cond_resched(kvm, &iter, false, true)) + continue; + + if (!is_shadow_present_pte(iter.old_spte) || + !is_last_spte(iter.old_spte, iter.level) || + !(iter.old_spte & PT_WRITABLE_MASK)) + continue; + + new_spte = iter.old_spte & ~PT_WRITABLE_MASK; + + if (tdp_mmu_set_spte_atomic(kvm, &iter, new_spte)) + goto retry; + + spte_set = true; + } + + rcu_read_unlock(); + return spte_set; +} + +/* + * Remove write access from all the SPTEs mapping GFNs in the memslot. Will + * only affect leaf SPTEs down to min_level. + * Returns true if an SPTE has been changed and the TLBs need to be flushed. + */ +bool kvm_tdp_mmu_wrprot_slot(struct kvm *kvm, + const struct kvm_memory_slot *slot, int min_level) +{ + struct kvm_mmu_page *root; + bool spte_set = false; + + lockdep_assert_held_read(&kvm->mmu_lock); + + for_each_valid_tdp_mmu_root_yield_safe(kvm, root, slot->as_id, true) + spte_set |= wrprot_gfn_range(kvm, root, slot->base_gfn, + slot->base_gfn + slot->npages, min_level); + + return spte_set; +} + +static struct kvm_mmu_page *__tdp_mmu_alloc_sp_for_split(gfp_t gfp) +{ + struct kvm_mmu_page *sp; + + gfp |= __GFP_ZERO; + + sp = kmem_cache_alloc(mmu_page_header_cache, gfp); + if (!sp) + return NULL; + + sp->spt = (void *)__get_free_page(gfp); + if (!sp->spt) { + kmem_cache_free(mmu_page_header_cache, sp); + return NULL; + } + + return sp; +} + +static struct kvm_mmu_page *tdp_mmu_alloc_sp_for_split(struct kvm *kvm, + struct tdp_iter *iter, + bool shared) +{ + struct kvm_mmu_page *sp; + + /* + * Since we are allocating while under the MMU lock we have to be + * careful about GFP flags. Use GFP_NOWAIT to avoid blocking on direct + * reclaim and to avoid making any filesystem callbacks (which can end + * up invoking KVM MMU notifiers, resulting in a deadlock). + * + * If this allocation fails we drop the lock and retry with reclaim + * allowed. + */ + sp = __tdp_mmu_alloc_sp_for_split(GFP_NOWAIT | __GFP_ACCOUNT); + if (sp) + return sp; + + rcu_read_unlock(); + + if (shared) + read_unlock(&kvm->mmu_lock); + else + write_unlock(&kvm->mmu_lock); + + iter->yielded = true; + sp = __tdp_mmu_alloc_sp_for_split(GFP_KERNEL_ACCOUNT); + + if (shared) + read_lock(&kvm->mmu_lock); + else + write_lock(&kvm->mmu_lock); + + rcu_read_lock(); + + return sp; +} + +static int tdp_mmu_split_huge_page(struct kvm *kvm, struct tdp_iter *iter, + struct kvm_mmu_page *sp, bool shared) +{ + const u64 huge_spte = iter->old_spte; + const int level = iter->level; + int ret, i; + + tdp_mmu_init_child_sp(sp, iter); + + /* + * No need for atomics when writing to sp->spt since the page table has + * not been linked in yet and thus is not reachable from any other CPU. + */ + for (i = 0; i < SPTE_ENT_PER_PAGE; i++) + sp->spt[i] = make_huge_page_split_spte(kvm, huge_spte, sp->role, i); + + /* + * Replace the huge spte with a pointer to the populated lower level + * page table. Since we are making this change without a TLB flush vCPUs + * will see a mix of the split mappings and the original huge mapping, + * depending on what's currently in their TLB. This is fine from a + * correctness standpoint since the translation will be the same either + * way. + */ + ret = tdp_mmu_link_sp(kvm, iter, sp, false, shared); + if (ret) + goto out; + + /* + * tdp_mmu_link_sp_atomic() will handle subtracting the huge page we + * are overwriting from the page stats. But we have to manually update + * the page stats with the new present child pages. + */ + kvm_update_page_stats(kvm, level - 1, SPTE_ENT_PER_PAGE); + +out: + trace_kvm_mmu_split_huge_page(iter->gfn, huge_spte, level, ret); + return ret; +} + +static int tdp_mmu_split_huge_pages_root(struct kvm *kvm, + struct kvm_mmu_page *root, + gfn_t start, gfn_t end, + int target_level, bool shared) +{ + struct kvm_mmu_page *sp = NULL; + struct tdp_iter iter; + int ret = 0; + + rcu_read_lock(); + + /* + * Traverse the page table splitting all huge pages above the target + * level into one lower level. For example, if we encounter a 1GB page + * we split it into 512 2MB pages. + * + * Since the TDP iterator uses a pre-order traversal, we are guaranteed + * to visit an SPTE before ever visiting its children, which means we + * will correctly recursively split huge pages that are more than one + * level above the target level (e.g. splitting a 1GB to 512 2MB pages, + * and then splitting each of those to 512 4KB pages). + */ + for_each_tdp_pte_min_level(iter, root, target_level + 1, start, end) { +retry: + if (tdp_mmu_iter_cond_resched(kvm, &iter, false, shared)) + continue; + + if (!is_shadow_present_pte(iter.old_spte) || !is_large_pte(iter.old_spte)) + continue; + + if (!sp) { + sp = tdp_mmu_alloc_sp_for_split(kvm, &iter, shared); + if (!sp) { + ret = -ENOMEM; + trace_kvm_mmu_split_huge_page(iter.gfn, + iter.old_spte, + iter.level, ret); + break; + } + + if (iter.yielded) + continue; + } + + if (tdp_mmu_split_huge_page(kvm, &iter, sp, shared)) + goto retry; + + sp = NULL; + } + + rcu_read_unlock(); + + /* + * It's possible to exit the loop having never used the last sp if, for + * example, a vCPU doing HugePage NX splitting wins the race and + * installs its own sp in place of the last sp we tried to split. + */ + if (sp) + tdp_mmu_free_sp(sp); + + return ret; +} + + +/* + * Try to split all huge pages mapped by the TDP MMU down to the target level. + */ +void kvm_tdp_mmu_try_split_huge_pages(struct kvm *kvm, + const struct kvm_memory_slot *slot, + gfn_t start, gfn_t end, + int target_level, bool shared) +{ + struct kvm_mmu_page *root; + int r = 0; + + kvm_lockdep_assert_mmu_lock_held(kvm, shared); + + for_each_valid_tdp_mmu_root_yield_safe(kvm, root, slot->as_id, shared) { + r = tdp_mmu_split_huge_pages_root(kvm, root, start, end, target_level, shared); + if (r) { + kvm_tdp_mmu_put_root(kvm, root, shared); + break; + } + } +} + +/* + * Clear the dirty status of all the SPTEs mapping GFNs in the memslot. If + * AD bits are enabled, this will involve clearing the dirty bit on each SPTE. + * If AD bits are not enabled, this will require clearing the writable bit on + * each SPTE. Returns true if an SPTE has been changed and the TLBs need to + * be flushed. + */ +static bool clear_dirty_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root, + gfn_t start, gfn_t end) +{ + struct tdp_iter iter; + u64 new_spte; + bool spte_set = false; + + rcu_read_lock(); + + tdp_root_for_each_leaf_pte(iter, root, start, end) { +retry: + if (tdp_mmu_iter_cond_resched(kvm, &iter, false, true)) + continue; + + if (!is_shadow_present_pte(iter.old_spte)) + continue; + + if (spte_ad_need_write_protect(iter.old_spte)) { + if (is_writable_pte(iter.old_spte)) + new_spte = iter.old_spte & ~PT_WRITABLE_MASK; + else + continue; + } else { + if (iter.old_spte & shadow_dirty_mask) + new_spte = iter.old_spte & ~shadow_dirty_mask; + else + continue; + } + + if (tdp_mmu_set_spte_atomic(kvm, &iter, new_spte)) + goto retry; + + spte_set = true; + } + + rcu_read_unlock(); + return spte_set; +} + +/* + * Clear the dirty status of all the SPTEs mapping GFNs in the memslot. If + * AD bits are enabled, this will involve clearing the dirty bit on each SPTE. + * If AD bits are not enabled, this will require clearing the writable bit on + * each SPTE. Returns true if an SPTE has been changed and the TLBs need to + * be flushed. + */ +bool kvm_tdp_mmu_clear_dirty_slot(struct kvm *kvm, + const struct kvm_memory_slot *slot) +{ + struct kvm_mmu_page *root; + bool spte_set = false; + + lockdep_assert_held_read(&kvm->mmu_lock); + + for_each_valid_tdp_mmu_root_yield_safe(kvm, root, slot->as_id, true) + spte_set |= clear_dirty_gfn_range(kvm, root, slot->base_gfn, + slot->base_gfn + slot->npages); + + return spte_set; +} + +/* + * Clears the dirty status of all the 4k SPTEs mapping GFNs for which a bit is + * set in mask, starting at gfn. The given memslot is expected to contain all + * the GFNs represented by set bits in the mask. If AD bits are enabled, + * clearing the dirty status will involve clearing the dirty bit on each SPTE + * or, if AD bits are not enabled, clearing the writable bit on each SPTE. + */ +static void clear_dirty_pt_masked(struct kvm *kvm, struct kvm_mmu_page *root, + gfn_t gfn, unsigned long mask, bool wrprot) +{ + struct tdp_iter iter; + u64 new_spte; + + rcu_read_lock(); + + tdp_root_for_each_leaf_pte(iter, root, gfn + __ffs(mask), + gfn + BITS_PER_LONG) { + if (!mask) + break; + + if (iter.level > PG_LEVEL_4K || + !(mask & (1UL << (iter.gfn - gfn)))) + continue; + + mask &= ~(1UL << (iter.gfn - gfn)); + + if (wrprot || spte_ad_need_write_protect(iter.old_spte)) { + if (is_writable_pte(iter.old_spte)) + new_spte = iter.old_spte & ~PT_WRITABLE_MASK; + else + continue; + } else { + if (iter.old_spte & shadow_dirty_mask) + new_spte = iter.old_spte & ~shadow_dirty_mask; + else + continue; + } + + tdp_mmu_set_spte_no_dirty_log(kvm, &iter, new_spte); + } + + rcu_read_unlock(); +} + +/* + * Clears the dirty status of all the 4k SPTEs mapping GFNs for which a bit is + * set in mask, starting at gfn. The given memslot is expected to contain all + * the GFNs represented by set bits in the mask. If AD bits are enabled, + * clearing the dirty status will involve clearing the dirty bit on each SPTE + * or, if AD bits are not enabled, clearing the writable bit on each SPTE. + */ +void kvm_tdp_mmu_clear_dirty_pt_masked(struct kvm *kvm, + struct kvm_memory_slot *slot, + gfn_t gfn, unsigned long mask, + bool wrprot) +{ + struct kvm_mmu_page *root; + + lockdep_assert_held_write(&kvm->mmu_lock); + for_each_tdp_mmu_root(kvm, root, slot->as_id) + clear_dirty_pt_masked(kvm, root, gfn, mask, wrprot); +} + +static void zap_collapsible_spte_range(struct kvm *kvm, + struct kvm_mmu_page *root, + const struct kvm_memory_slot *slot) +{ + gfn_t start = slot->base_gfn; + gfn_t end = start + slot->npages; + struct tdp_iter iter; + int max_mapping_level; + + rcu_read_lock(); + + for_each_tdp_pte_min_level(iter, root, PG_LEVEL_2M, start, end) { +retry: + if (tdp_mmu_iter_cond_resched(kvm, &iter, false, true)) + continue; + + if (iter.level > KVM_MAX_HUGEPAGE_LEVEL || + !is_shadow_present_pte(iter.old_spte)) + continue; + + /* + * Don't zap leaf SPTEs, if a leaf SPTE could be replaced with + * a large page size, then its parent would have been zapped + * instead of stepping down. + */ + if (is_last_spte(iter.old_spte, iter.level)) + continue; + + /* + * If iter.gfn resides outside of the slot, i.e. the page for + * the current level overlaps but is not contained by the slot, + * then the SPTE can't be made huge. More importantly, trying + * to query that info from slot->arch.lpage_info will cause an + * out-of-bounds access. + */ + if (iter.gfn < start || iter.gfn >= end) + continue; + + max_mapping_level = kvm_mmu_max_mapping_level(kvm, slot, + iter.gfn, PG_LEVEL_NUM); + if (max_mapping_level < iter.level) + continue; + + /* Note, a successful atomic zap also does a remote TLB flush. */ + if (tdp_mmu_zap_spte_atomic(kvm, &iter)) + goto retry; + } + + rcu_read_unlock(); +} + +/* + * Zap non-leaf SPTEs (and free their associated page tables) which could + * be replaced by huge pages, for GFNs within the slot. + */ +void kvm_tdp_mmu_zap_collapsible_sptes(struct kvm *kvm, + const struct kvm_memory_slot *slot) +{ + struct kvm_mmu_page *root; + + lockdep_assert_held_read(&kvm->mmu_lock); + + for_each_valid_tdp_mmu_root_yield_safe(kvm, root, slot->as_id, true) + zap_collapsible_spte_range(kvm, root, slot); +} + +/* + * Removes write access on the last level SPTE mapping this GFN and unsets the + * MMU-writable bit to ensure future writes continue to be intercepted. + * Returns true if an SPTE was set and a TLB flush is needed. + */ +static bool write_protect_gfn(struct kvm *kvm, struct kvm_mmu_page *root, + gfn_t gfn, int min_level) +{ + struct tdp_iter iter; + u64 new_spte; + bool spte_set = false; + + BUG_ON(min_level > KVM_MAX_HUGEPAGE_LEVEL); + + rcu_read_lock(); + + for_each_tdp_pte_min_level(iter, root, min_level, gfn, gfn + 1) { + if (!is_shadow_present_pte(iter.old_spte) || + !is_last_spte(iter.old_spte, iter.level)) + continue; + + new_spte = iter.old_spte & + ~(PT_WRITABLE_MASK | shadow_mmu_writable_mask); + + if (new_spte == iter.old_spte) + break; + + tdp_mmu_set_spte(kvm, &iter, new_spte); + spte_set = true; + } + + rcu_read_unlock(); + + return spte_set; +} + +/* + * Removes write access on the last level SPTE mapping this GFN and unsets the + * MMU-writable bit to ensure future writes continue to be intercepted. + * Returns true if an SPTE was set and a TLB flush is needed. + */ +bool kvm_tdp_mmu_write_protect_gfn(struct kvm *kvm, + struct kvm_memory_slot *slot, gfn_t gfn, + int min_level) +{ + struct kvm_mmu_page *root; + bool spte_set = false; + + lockdep_assert_held_write(&kvm->mmu_lock); + for_each_tdp_mmu_root(kvm, root, slot->as_id) + spte_set |= write_protect_gfn(kvm, root, gfn, min_level); + + return spte_set; +} + +/* + * Return the level of the lowest level SPTE added to sptes. + * That SPTE may be non-present. + * + * Must be called between kvm_tdp_mmu_walk_lockless_{begin,end}. + */ +int kvm_tdp_mmu_get_walk(struct kvm_vcpu *vcpu, u64 addr, u64 *sptes, + int *root_level) +{ + struct tdp_iter iter; + struct kvm_mmu *mmu = vcpu->arch.mmu; + gfn_t gfn = addr >> PAGE_SHIFT; + int leaf = -1; + + *root_level = vcpu->arch.mmu->root_role.level; + + tdp_mmu_for_each_pte(iter, mmu, gfn, gfn + 1) { + leaf = iter.level; + sptes[leaf] = iter.old_spte; + } + + return leaf; +} + +/* + * Returns the last level spte pointer of the shadow page walk for the given + * gpa, and sets *spte to the spte value. This spte may be non-preset. If no + * walk could be performed, returns NULL and *spte does not contain valid data. + * + * Contract: + * - Must be called between kvm_tdp_mmu_walk_lockless_{begin,end}. + * - The returned sptep must not be used after kvm_tdp_mmu_walk_lockless_end. + * + * WARNING: This function is only intended to be called during fast_page_fault. + */ +u64 *kvm_tdp_mmu_fast_pf_get_last_sptep(struct kvm_vcpu *vcpu, u64 addr, + u64 *spte) +{ + struct tdp_iter iter; + struct kvm_mmu *mmu = vcpu->arch.mmu; + gfn_t gfn = addr >> PAGE_SHIFT; + tdp_ptep_t sptep = NULL; + + tdp_mmu_for_each_pte(iter, mmu, gfn, gfn + 1) { + *spte = iter.old_spte; + sptep = iter.sptep; + } + + /* + * Perform the rcu_dereference to get the raw spte pointer value since + * we are passing it up to fast_page_fault, which is shared with the + * legacy MMU and thus does not retain the TDP MMU-specific __rcu + * annotation. + * + * This is safe since fast_page_fault obeys the contracts of this + * function as well as all TDP MMU contracts around modifying SPTEs + * outside of mmu_lock. + */ + return rcu_dereference(sptep); +} diff --git a/arch/x86/kvm/mmu/tdp_mmu.h b/arch/x86/kvm/mmu/tdp_mmu.h new file mode 100644 index 000000000..c82a8bb32 --- /dev/null +++ b/arch/x86/kvm/mmu/tdp_mmu.h @@ -0,0 +1,95 @@ +// SPDX-License-Identifier: GPL-2.0 + +#ifndef __KVM_X86_MMU_TDP_MMU_H +#define __KVM_X86_MMU_TDP_MMU_H + +#include <linux/kvm_host.h> + +hpa_t kvm_tdp_mmu_get_vcpu_root_hpa(struct kvm_vcpu *vcpu); + +__must_check static inline bool kvm_tdp_mmu_get_root(struct kvm_mmu_page *root) +{ + return refcount_inc_not_zero(&root->tdp_mmu_root_count); +} + +void kvm_tdp_mmu_put_root(struct kvm *kvm, struct kvm_mmu_page *root, + bool shared); + +bool kvm_tdp_mmu_zap_leafs(struct kvm *kvm, gfn_t start, gfn_t end, bool flush); +bool kvm_tdp_mmu_zap_sp(struct kvm *kvm, struct kvm_mmu_page *sp); +void kvm_tdp_mmu_zap_all(struct kvm *kvm); +void kvm_tdp_mmu_invalidate_all_roots(struct kvm *kvm); +void kvm_tdp_mmu_zap_invalidated_roots(struct kvm *kvm); + +int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault); + +bool kvm_tdp_mmu_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range, + bool flush); +bool kvm_tdp_mmu_age_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range); +bool kvm_tdp_mmu_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range); +bool kvm_tdp_mmu_set_spte_gfn(struct kvm *kvm, struct kvm_gfn_range *range); + +bool kvm_tdp_mmu_wrprot_slot(struct kvm *kvm, + const struct kvm_memory_slot *slot, int min_level); +bool kvm_tdp_mmu_clear_dirty_slot(struct kvm *kvm, + const struct kvm_memory_slot *slot); +void kvm_tdp_mmu_clear_dirty_pt_masked(struct kvm *kvm, + struct kvm_memory_slot *slot, + gfn_t gfn, unsigned long mask, + bool wrprot); +void kvm_tdp_mmu_zap_collapsible_sptes(struct kvm *kvm, + const struct kvm_memory_slot *slot); + +bool kvm_tdp_mmu_write_protect_gfn(struct kvm *kvm, + struct kvm_memory_slot *slot, gfn_t gfn, + int min_level); + +void kvm_tdp_mmu_try_split_huge_pages(struct kvm *kvm, + const struct kvm_memory_slot *slot, + gfn_t start, gfn_t end, + int target_level, bool shared); + +static inline void kvm_tdp_mmu_walk_lockless_begin(void) +{ + rcu_read_lock(); +} + +static inline void kvm_tdp_mmu_walk_lockless_end(void) +{ + rcu_read_unlock(); +} + +int kvm_tdp_mmu_get_walk(struct kvm_vcpu *vcpu, u64 addr, u64 *sptes, + int *root_level); +u64 *kvm_tdp_mmu_fast_pf_get_last_sptep(struct kvm_vcpu *vcpu, u64 addr, + u64 *spte); + +#ifdef CONFIG_X86_64 +void kvm_mmu_init_tdp_mmu(struct kvm *kvm); +void kvm_mmu_uninit_tdp_mmu(struct kvm *kvm); +static inline bool is_tdp_mmu_page(struct kvm_mmu_page *sp) { return sp->tdp_mmu_page; } + +static inline bool is_tdp_mmu(struct kvm_mmu *mmu) +{ + struct kvm_mmu_page *sp; + hpa_t hpa = mmu->root.hpa; + + if (WARN_ON(!VALID_PAGE(hpa))) + return false; + + /* + * A NULL shadow page is legal when shadowing a non-paging guest with + * PAE paging, as the MMU will be direct with root_hpa pointing at the + * pae_root page, not a shadow page. + */ + sp = to_shadow_page(hpa); + return sp && is_tdp_mmu_page(sp) && sp->root_count; +} +#else +static inline void kvm_mmu_init_tdp_mmu(struct kvm *kvm) {} +static inline void kvm_mmu_uninit_tdp_mmu(struct kvm *kvm) {} +static inline bool is_tdp_mmu_page(struct kvm_mmu_page *sp) { return false; } +static inline bool is_tdp_mmu(struct kvm_mmu *mmu) { return false; } +#endif + +#endif /* __KVM_X86_MMU_TDP_MMU_H */ |