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Diffstat (limited to '')
| -rw-r--r-- | arch/mips/kvm/mmu.c | 1235 |
1 files changed, 1235 insertions, 0 deletions
diff --git a/arch/mips/kvm/mmu.c b/arch/mips/kvm/mmu.c new file mode 100644 index 000000000..38a5be10a --- /dev/null +++ b/arch/mips/kvm/mmu.c @@ -0,0 +1,1235 @@ +/* + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file "COPYING" in the main directory of this archive + * for more details. + * + * KVM/MIPS MMU handling in the KVM module. + * + * Copyright (C) 2012 MIPS Technologies, Inc. All rights reserved. + * Authors: Sanjay Lal <sanjayl@kymasys.com> + */ + +#include <linux/highmem.h> +#include <linux/kvm_host.h> +#include <linux/uaccess.h> +#include <asm/mmu_context.h> +#include <asm/pgalloc.h> + +/* + * KVM_MMU_CACHE_MIN_PAGES is the number of GPA page table translation levels + * for which pages need to be cached. + */ +#if defined(__PAGETABLE_PMD_FOLDED) +#define KVM_MMU_CACHE_MIN_PAGES 1 +#else +#define KVM_MMU_CACHE_MIN_PAGES 2 +#endif + +void kvm_mmu_free_memory_caches(struct kvm_vcpu *vcpu) +{ + kvm_mmu_free_memory_cache(&vcpu->arch.mmu_page_cache); +} + +/** + * kvm_pgd_init() - Initialise KVM GPA page directory. + * @page: Pointer to page directory (PGD) for KVM GPA. + * + * Initialise a KVM GPA page directory with pointers to the invalid table, i.e. + * representing no mappings. This is similar to pgd_init(), however it + * initialises all the page directory pointers, not just the ones corresponding + * to the userland address space (since it is for the guest physical address + * space rather than a virtual address space). + */ +static void kvm_pgd_init(void *page) +{ + unsigned long *p, *end; + unsigned long entry; + +#ifdef __PAGETABLE_PMD_FOLDED + entry = (unsigned long)invalid_pte_table; +#else + entry = (unsigned long)invalid_pmd_table; +#endif + + p = (unsigned long *)page; + end = p + PTRS_PER_PGD; + + do { + p[0] = entry; + p[1] = entry; + p[2] = entry; + p[3] = entry; + p[4] = entry; + p += 8; + p[-3] = entry; + p[-2] = entry; + p[-1] = entry; + } while (p != end); +} + +/** + * kvm_pgd_alloc() - Allocate and initialise a KVM GPA page directory. + * + * Allocate a blank KVM GPA page directory (PGD) for representing guest physical + * to host physical page mappings. + * + * Returns: Pointer to new KVM GPA page directory. + * NULL on allocation failure. + */ +pgd_t *kvm_pgd_alloc(void) +{ + pgd_t *ret; + + ret = (pgd_t *)__get_free_pages(GFP_KERNEL, PGD_ORDER); + if (ret) + kvm_pgd_init(ret); + + return ret; +} + +/** + * kvm_mips_walk_pgd() - Walk page table with optional allocation. + * @pgd: Page directory pointer. + * @addr: Address to index page table using. + * @cache: MMU page cache to allocate new page tables from, or NULL. + * + * Walk the page tables pointed to by @pgd to find the PTE corresponding to the + * address @addr. If page tables don't exist for @addr, they will be created + * from the MMU cache if @cache is not NULL. + * + * Returns: Pointer to pte_t corresponding to @addr. + * NULL if a page table doesn't exist for @addr and !@cache. + * NULL if a page table allocation failed. + */ +static pte_t *kvm_mips_walk_pgd(pgd_t *pgd, struct kvm_mmu_memory_cache *cache, + unsigned long addr) +{ + p4d_t *p4d; + pud_t *pud; + pmd_t *pmd; + + pgd += pgd_index(addr); + if (pgd_none(*pgd)) { + /* Not used on MIPS yet */ + BUG(); + return NULL; + } + p4d = p4d_offset(pgd, addr); + pud = pud_offset(p4d, addr); + if (pud_none(*pud)) { + pmd_t *new_pmd; + + if (!cache) + return NULL; + new_pmd = kvm_mmu_memory_cache_alloc(cache); + pmd_init((unsigned long)new_pmd, + (unsigned long)invalid_pte_table); + pud_populate(NULL, pud, new_pmd); + } + pmd = pmd_offset(pud, addr); + if (pmd_none(*pmd)) { + pte_t *new_pte; + + if (!cache) + return NULL; + new_pte = kvm_mmu_memory_cache_alloc(cache); + clear_page(new_pte); + pmd_populate_kernel(NULL, pmd, new_pte); + } + return pte_offset_kernel(pmd, addr); +} + +/* Caller must hold kvm->mm_lock */ +static pte_t *kvm_mips_pte_for_gpa(struct kvm *kvm, + struct kvm_mmu_memory_cache *cache, + unsigned long addr) +{ + return kvm_mips_walk_pgd(kvm->arch.gpa_mm.pgd, cache, addr); +} + +/* + * kvm_mips_flush_gpa_{pte,pmd,pud,pgd,pt}. + * Flush a range of guest physical address space from the VM's GPA page tables. + */ + +static bool kvm_mips_flush_gpa_pte(pte_t *pte, unsigned long start_gpa, + unsigned long end_gpa) +{ + int i_min = pte_index(start_gpa); + int i_max = pte_index(end_gpa); + bool safe_to_remove = (i_min == 0 && i_max == PTRS_PER_PTE - 1); + int i; + + for (i = i_min; i <= i_max; ++i) { + if (!pte_present(pte[i])) + continue; + + set_pte(pte + i, __pte(0)); + } + return safe_to_remove; +} + +static bool kvm_mips_flush_gpa_pmd(pmd_t *pmd, unsigned long start_gpa, + unsigned long end_gpa) +{ + pte_t *pte; + unsigned long end = ~0ul; + int i_min = pmd_index(start_gpa); + int i_max = pmd_index(end_gpa); + bool safe_to_remove = (i_min == 0 && i_max == PTRS_PER_PMD - 1); + int i; + + for (i = i_min; i <= i_max; ++i, start_gpa = 0) { + if (!pmd_present(pmd[i])) + continue; + + pte = pte_offset_kernel(pmd + i, 0); + if (i == i_max) + end = end_gpa; + + if (kvm_mips_flush_gpa_pte(pte, start_gpa, end)) { + pmd_clear(pmd + i); + pte_free_kernel(NULL, pte); + } else { + safe_to_remove = false; + } + } + return safe_to_remove; +} + +static bool kvm_mips_flush_gpa_pud(pud_t *pud, unsigned long start_gpa, + unsigned long end_gpa) +{ + pmd_t *pmd; + unsigned long end = ~0ul; + int i_min = pud_index(start_gpa); + int i_max = pud_index(end_gpa); + bool safe_to_remove = (i_min == 0 && i_max == PTRS_PER_PUD - 1); + int i; + + for (i = i_min; i <= i_max; ++i, start_gpa = 0) { + if (!pud_present(pud[i])) + continue; + + pmd = pmd_offset(pud + i, 0); + if (i == i_max) + end = end_gpa; + + if (kvm_mips_flush_gpa_pmd(pmd, start_gpa, end)) { + pud_clear(pud + i); + pmd_free(NULL, pmd); + } else { + safe_to_remove = false; + } + } + return safe_to_remove; +} + +static bool kvm_mips_flush_gpa_pgd(pgd_t *pgd, unsigned long start_gpa, + unsigned long end_gpa) +{ + p4d_t *p4d; + pud_t *pud; + unsigned long end = ~0ul; + int i_min = pgd_index(start_gpa); + int i_max = pgd_index(end_gpa); + bool safe_to_remove = (i_min == 0 && i_max == PTRS_PER_PGD - 1); + int i; + + for (i = i_min; i <= i_max; ++i, start_gpa = 0) { + if (!pgd_present(pgd[i])) + continue; + + p4d = p4d_offset(pgd, 0); + pud = pud_offset(p4d + i, 0); + if (i == i_max) + end = end_gpa; + + if (kvm_mips_flush_gpa_pud(pud, start_gpa, end)) { + pgd_clear(pgd + i); + pud_free(NULL, pud); + } else { + safe_to_remove = false; + } + } + return safe_to_remove; +} + +/** + * kvm_mips_flush_gpa_pt() - Flush a range of guest physical addresses. + * @kvm: KVM pointer. + * @start_gfn: Guest frame number of first page in GPA range to flush. + * @end_gfn: Guest frame number of last page in GPA range to flush. + * + * Flushes a range of GPA mappings from the GPA page tables. + * + * The caller must hold the @kvm->mmu_lock spinlock. + * + * Returns: Whether its safe to remove the top level page directory because + * all lower levels have been removed. + */ +bool kvm_mips_flush_gpa_pt(struct kvm *kvm, gfn_t start_gfn, gfn_t end_gfn) +{ + return kvm_mips_flush_gpa_pgd(kvm->arch.gpa_mm.pgd, + start_gfn << PAGE_SHIFT, + end_gfn << PAGE_SHIFT); +} + +#define BUILD_PTE_RANGE_OP(name, op) \ +static int kvm_mips_##name##_pte(pte_t *pte, unsigned long start, \ + unsigned long end) \ +{ \ + int ret = 0; \ + int i_min = pte_index(start); \ + int i_max = pte_index(end); \ + int i; \ + pte_t old, new; \ + \ + for (i = i_min; i <= i_max; ++i) { \ + if (!pte_present(pte[i])) \ + continue; \ + \ + old = pte[i]; \ + new = op(old); \ + if (pte_val(new) == pte_val(old)) \ + continue; \ + set_pte(pte + i, new); \ + ret = 1; \ + } \ + return ret; \ +} \ + \ +/* returns true if anything was done */ \ +static int kvm_mips_##name##_pmd(pmd_t *pmd, unsigned long start, \ + unsigned long end) \ +{ \ + int ret = 0; \ + pte_t *pte; \ + unsigned long cur_end = ~0ul; \ + int i_min = pmd_index(start); \ + int i_max = pmd_index(end); \ + int i; \ + \ + for (i = i_min; i <= i_max; ++i, start = 0) { \ + if (!pmd_present(pmd[i])) \ + continue; \ + \ + pte = pte_offset_kernel(pmd + i, 0); \ + if (i == i_max) \ + cur_end = end; \ + \ + ret |= kvm_mips_##name##_pte(pte, start, cur_end); \ + } \ + return ret; \ +} \ + \ +static int kvm_mips_##name##_pud(pud_t *pud, unsigned long start, \ + unsigned long end) \ +{ \ + int ret = 0; \ + pmd_t *pmd; \ + unsigned long cur_end = ~0ul; \ + int i_min = pud_index(start); \ + int i_max = pud_index(end); \ + int i; \ + \ + for (i = i_min; i <= i_max; ++i, start = 0) { \ + if (!pud_present(pud[i])) \ + continue; \ + \ + pmd = pmd_offset(pud + i, 0); \ + if (i == i_max) \ + cur_end = end; \ + \ + ret |= kvm_mips_##name##_pmd(pmd, start, cur_end); \ + } \ + return ret; \ +} \ + \ +static int kvm_mips_##name##_pgd(pgd_t *pgd, unsigned long start, \ + unsigned long end) \ +{ \ + int ret = 0; \ + p4d_t *p4d; \ + pud_t *pud; \ + unsigned long cur_end = ~0ul; \ + int i_min = pgd_index(start); \ + int i_max = pgd_index(end); \ + int i; \ + \ + for (i = i_min; i <= i_max; ++i, start = 0) { \ + if (!pgd_present(pgd[i])) \ + continue; \ + \ + p4d = p4d_offset(pgd, 0); \ + pud = pud_offset(p4d + i, 0); \ + if (i == i_max) \ + cur_end = end; \ + \ + ret |= kvm_mips_##name##_pud(pud, start, cur_end); \ + } \ + return ret; \ +} + +/* + * kvm_mips_mkclean_gpa_pt. + * Mark a range of guest physical address space clean (writes fault) in the VM's + * GPA page table to allow dirty page tracking. + */ + +BUILD_PTE_RANGE_OP(mkclean, pte_mkclean) + +/** + * kvm_mips_mkclean_gpa_pt() - Make a range of guest physical addresses clean. + * @kvm: KVM pointer. + * @start_gfn: Guest frame number of first page in GPA range to flush. + * @end_gfn: Guest frame number of last page in GPA range to flush. + * + * Make a range of GPA mappings clean so that guest writes will fault and + * trigger dirty page logging. + * + * The caller must hold the @kvm->mmu_lock spinlock. + * + * Returns: Whether any GPA mappings were modified, which would require + * derived mappings (GVA page tables & TLB enties) to be + * invalidated. + */ +int kvm_mips_mkclean_gpa_pt(struct kvm *kvm, gfn_t start_gfn, gfn_t end_gfn) +{ + return kvm_mips_mkclean_pgd(kvm->arch.gpa_mm.pgd, + start_gfn << PAGE_SHIFT, + end_gfn << PAGE_SHIFT); +} + +/** + * kvm_arch_mmu_enable_log_dirty_pt_masked() - write protect dirty pages + * @kvm: The KVM pointer + * @slot: The memory slot associated with mask + * @gfn_offset: The gfn offset in memory slot + * @mask: The mask of dirty pages at offset 'gfn_offset' in this memory + * slot to be write protected + * + * Walks bits set in mask write protects the associated pte's. Caller must + * acquire @kvm->mmu_lock. + */ +void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm, + struct kvm_memory_slot *slot, + gfn_t gfn_offset, unsigned long mask) +{ + gfn_t base_gfn = slot->base_gfn + gfn_offset; + gfn_t start = base_gfn + __ffs(mask); + gfn_t end = base_gfn + __fls(mask); + + kvm_mips_mkclean_gpa_pt(kvm, start, end); +} + +/* + * kvm_mips_mkold_gpa_pt. + * Mark a range of guest physical address space old (all accesses fault) in the + * VM's GPA page table to allow detection of commonly used pages. + */ + +BUILD_PTE_RANGE_OP(mkold, pte_mkold) + +static int kvm_mips_mkold_gpa_pt(struct kvm *kvm, gfn_t start_gfn, + gfn_t end_gfn) +{ + return kvm_mips_mkold_pgd(kvm->arch.gpa_mm.pgd, + start_gfn << PAGE_SHIFT, + end_gfn << PAGE_SHIFT); +} + +static int handle_hva_to_gpa(struct kvm *kvm, + unsigned long start, + unsigned long end, + int (*handler)(struct kvm *kvm, gfn_t gfn, + gpa_t gfn_end, + struct kvm_memory_slot *memslot, + void *data), + void *data) +{ + struct kvm_memslots *slots; + struct kvm_memory_slot *memslot; + int ret = 0; + + slots = kvm_memslots(kvm); + + /* we only care about the pages that the guest sees */ + kvm_for_each_memslot(memslot, slots) { + unsigned long hva_start, hva_end; + gfn_t gfn, gfn_end; + + hva_start = max(start, memslot->userspace_addr); + hva_end = min(end, memslot->userspace_addr + + (memslot->npages << PAGE_SHIFT)); + if (hva_start >= hva_end) + continue; + + /* + * {gfn(page) | page intersects with [hva_start, hva_end)} = + * {gfn_start, gfn_start+1, ..., gfn_end-1}. + */ + gfn = hva_to_gfn_memslot(hva_start, memslot); + gfn_end = hva_to_gfn_memslot(hva_end + PAGE_SIZE - 1, memslot); + + ret |= handler(kvm, gfn, gfn_end, memslot, data); + } + + return ret; +} + + +static int kvm_unmap_hva_handler(struct kvm *kvm, gfn_t gfn, gfn_t gfn_end, + struct kvm_memory_slot *memslot, void *data) +{ + kvm_mips_flush_gpa_pt(kvm, gfn, gfn_end); + return 1; +} + +int kvm_unmap_hva_range(struct kvm *kvm, unsigned long start, unsigned long end, + unsigned flags) +{ + handle_hva_to_gpa(kvm, start, end, &kvm_unmap_hva_handler, NULL); + + kvm_mips_callbacks->flush_shadow_all(kvm); + return 0; +} + +static int kvm_set_spte_handler(struct kvm *kvm, gfn_t gfn, gfn_t gfn_end, + struct kvm_memory_slot *memslot, void *data) +{ + gpa_t gpa = gfn << PAGE_SHIFT; + pte_t hva_pte = *(pte_t *)data; + pte_t *gpa_pte = kvm_mips_pte_for_gpa(kvm, NULL, gpa); + pte_t old_pte; + + if (!gpa_pte) + return 0; + + /* Mapping may need adjusting depending on memslot flags */ + old_pte = *gpa_pte; + if (memslot->flags & KVM_MEM_LOG_DIRTY_PAGES && !pte_dirty(old_pte)) + hva_pte = pte_mkclean(hva_pte); + else if (memslot->flags & KVM_MEM_READONLY) + hva_pte = pte_wrprotect(hva_pte); + + set_pte(gpa_pte, hva_pte); + + /* Replacing an absent or old page doesn't need flushes */ + if (!pte_present(old_pte) || !pte_young(old_pte)) + return 0; + + /* Pages swapped, aged, moved, or cleaned require flushes */ + return !pte_present(hva_pte) || + !pte_young(hva_pte) || + pte_pfn(old_pte) != pte_pfn(hva_pte) || + (pte_dirty(old_pte) && !pte_dirty(hva_pte)); +} + +int kvm_set_spte_hva(struct kvm *kvm, unsigned long hva, pte_t pte) +{ + unsigned long end = hva + PAGE_SIZE; + int ret; + + ret = handle_hva_to_gpa(kvm, hva, end, &kvm_set_spte_handler, &pte); + if (ret) + kvm_mips_callbacks->flush_shadow_all(kvm); + return 0; +} + +static int kvm_age_hva_handler(struct kvm *kvm, gfn_t gfn, gfn_t gfn_end, + struct kvm_memory_slot *memslot, void *data) +{ + return kvm_mips_mkold_gpa_pt(kvm, gfn, gfn_end); +} + +static int kvm_test_age_hva_handler(struct kvm *kvm, gfn_t gfn, gfn_t gfn_end, + struct kvm_memory_slot *memslot, void *data) +{ + gpa_t gpa = gfn << PAGE_SHIFT; + pte_t *gpa_pte = kvm_mips_pte_for_gpa(kvm, NULL, gpa); + + if (!gpa_pte) + return 0; + return pte_young(*gpa_pte); +} + +int kvm_age_hva(struct kvm *kvm, unsigned long start, unsigned long end) +{ + return handle_hva_to_gpa(kvm, start, end, kvm_age_hva_handler, NULL); +} + +int kvm_test_age_hva(struct kvm *kvm, unsigned long hva) +{ + return handle_hva_to_gpa(kvm, hva, hva, kvm_test_age_hva_handler, NULL); +} + +/** + * _kvm_mips_map_page_fast() - Fast path GPA fault handler. + * @vcpu: VCPU pointer. + * @gpa: Guest physical address of fault. + * @write_fault: Whether the fault was due to a write. + * @out_entry: New PTE for @gpa (written on success unless NULL). + * @out_buddy: New PTE for @gpa's buddy (written on success unless + * NULL). + * + * Perform fast path GPA fault handling, doing all that can be done without + * calling into KVM. This handles marking old pages young (for idle page + * tracking), and dirtying of clean pages (for dirty page logging). + * + * Returns: 0 on success, in which case we can update derived mappings and + * resume guest execution. + * -EFAULT on failure due to absent GPA mapping or write to + * read-only page, in which case KVM must be consulted. + */ +static int _kvm_mips_map_page_fast(struct kvm_vcpu *vcpu, unsigned long gpa, + bool write_fault, + pte_t *out_entry, pte_t *out_buddy) +{ + struct kvm *kvm = vcpu->kvm; + gfn_t gfn = gpa >> PAGE_SHIFT; + pte_t *ptep; + kvm_pfn_t pfn = 0; /* silence bogus GCC warning */ + bool pfn_valid = false; + int ret = 0; + + spin_lock(&kvm->mmu_lock); + + /* Fast path - just check GPA page table for an existing entry */ + ptep = kvm_mips_pte_for_gpa(kvm, NULL, gpa); + if (!ptep || !pte_present(*ptep)) { + ret = -EFAULT; + goto out; + } + + /* Track access to pages marked old */ + if (!pte_young(*ptep)) { + set_pte(ptep, pte_mkyoung(*ptep)); + pfn = pte_pfn(*ptep); + pfn_valid = true; + /* call kvm_set_pfn_accessed() after unlock */ + } + if (write_fault && !pte_dirty(*ptep)) { + if (!pte_write(*ptep)) { + ret = -EFAULT; + goto out; + } + + /* Track dirtying of writeable pages */ + set_pte(ptep, pte_mkdirty(*ptep)); + pfn = pte_pfn(*ptep); + mark_page_dirty(kvm, gfn); + kvm_set_pfn_dirty(pfn); + } + + if (out_entry) + *out_entry = *ptep; + if (out_buddy) + *out_buddy = *ptep_buddy(ptep); + +out: + spin_unlock(&kvm->mmu_lock); + if (pfn_valid) + kvm_set_pfn_accessed(pfn); + return ret; +} + +/** + * kvm_mips_map_page() - Map a guest physical page. + * @vcpu: VCPU pointer. + * @gpa: Guest physical address of fault. + * @write_fault: Whether the fault was due to a write. + * @out_entry: New PTE for @gpa (written on success unless NULL). + * @out_buddy: New PTE for @gpa's buddy (written on success unless + * NULL). + * + * Handle GPA faults by creating a new GPA mapping (or updating an existing + * one). + * + * This takes care of marking pages young or dirty (idle/dirty page tracking), + * asking KVM for the corresponding PFN, and creating a mapping in the GPA page + * tables. Derived mappings (GVA page tables and TLBs) must be handled by the + * caller. + * + * Returns: 0 on success, in which case the caller may use the @out_entry + * and @out_buddy PTEs to update derived mappings and resume guest + * execution. + * -EFAULT if there is no memory region at @gpa or a write was + * attempted to a read-only memory region. This is usually handled + * as an MMIO access. + */ +static int kvm_mips_map_page(struct kvm_vcpu *vcpu, unsigned long gpa, + bool write_fault, + pte_t *out_entry, pte_t *out_buddy) +{ + struct kvm *kvm = vcpu->kvm; + struct kvm_mmu_memory_cache *memcache = &vcpu->arch.mmu_page_cache; + gfn_t gfn = gpa >> PAGE_SHIFT; + int srcu_idx, err; + kvm_pfn_t pfn; + pte_t *ptep, entry; + bool writeable; + unsigned long prot_bits; + unsigned long mmu_seq; + + /* Try the fast path to handle old / clean pages */ + srcu_idx = srcu_read_lock(&kvm->srcu); + err = _kvm_mips_map_page_fast(vcpu, gpa, write_fault, out_entry, + out_buddy); + if (!err) + goto out; + + /* We need a minimum of cached pages ready for page table creation */ + err = kvm_mmu_topup_memory_cache(memcache, KVM_MMU_CACHE_MIN_PAGES); + if (err) + goto out; + +retry: + /* + * Used to check for invalidations in progress, of the pfn that is + * returned by pfn_to_pfn_prot below. + */ + mmu_seq = kvm->mmu_notifier_seq; + /* + * Ensure the read of mmu_notifier_seq isn't reordered with PTE reads in + * gfn_to_pfn_prot() (which calls get_user_pages()), so that we don't + * risk the page we get a reference to getting unmapped before we have a + * chance to grab the mmu_lock without mmu_notifier_retry() noticing. + * + * This smp_rmb() pairs with the effective smp_wmb() of the combination + * of the pte_unmap_unlock() after the PTE is zapped, and the + * spin_lock() in kvm_mmu_notifier_invalidate_<page|range_end>() before + * mmu_notifier_seq is incremented. + */ + smp_rmb(); + + /* Slow path - ask KVM core whether we can access this GPA */ + pfn = gfn_to_pfn_prot(kvm, gfn, write_fault, &writeable); + if (is_error_noslot_pfn(pfn)) { + err = -EFAULT; + goto out; + } + + spin_lock(&kvm->mmu_lock); + /* Check if an invalidation has taken place since we got pfn */ + if (mmu_notifier_retry(kvm, mmu_seq)) { + /* + * This can happen when mappings are changed asynchronously, but + * also synchronously if a COW is triggered by + * gfn_to_pfn_prot(). + */ + spin_unlock(&kvm->mmu_lock); + kvm_release_pfn_clean(pfn); + goto retry; + } + + /* Ensure page tables are allocated */ + ptep = kvm_mips_pte_for_gpa(kvm, memcache, gpa); + + /* Set up the PTE */ + prot_bits = _PAGE_PRESENT | __READABLE | _page_cachable_default; + if (writeable) { + prot_bits |= _PAGE_WRITE; + if (write_fault) { + prot_bits |= __WRITEABLE; + mark_page_dirty(kvm, gfn); + kvm_set_pfn_dirty(pfn); + } + } + entry = pfn_pte(pfn, __pgprot(prot_bits)); + + /* Write the PTE */ + set_pte(ptep, entry); + + err = 0; + if (out_entry) + *out_entry = *ptep; + if (out_buddy) + *out_buddy = *ptep_buddy(ptep); + + spin_unlock(&kvm->mmu_lock); + kvm_release_pfn_clean(pfn); + kvm_set_pfn_accessed(pfn); +out: + srcu_read_unlock(&kvm->srcu, srcu_idx); + return err; +} + +static pte_t *kvm_trap_emul_pte_for_gva(struct kvm_vcpu *vcpu, + unsigned long addr) +{ + struct kvm_mmu_memory_cache *memcache = &vcpu->arch.mmu_page_cache; + pgd_t *pgdp; + int ret; + + /* We need a minimum of cached pages ready for page table creation */ + ret = kvm_mmu_topup_memory_cache(memcache, KVM_MMU_CACHE_MIN_PAGES); + if (ret) + return NULL; + + if (KVM_GUEST_KERNEL_MODE(vcpu)) + pgdp = vcpu->arch.guest_kernel_mm.pgd; + else + pgdp = vcpu->arch.guest_user_mm.pgd; + + return kvm_mips_walk_pgd(pgdp, memcache, addr); +} + +void kvm_trap_emul_invalidate_gva(struct kvm_vcpu *vcpu, unsigned long addr, + bool user) +{ + pgd_t *pgdp; + pte_t *ptep; + + addr &= PAGE_MASK << 1; + + pgdp = vcpu->arch.guest_kernel_mm.pgd; + ptep = kvm_mips_walk_pgd(pgdp, NULL, addr); + if (ptep) { + ptep[0] = pfn_pte(0, __pgprot(0)); + ptep[1] = pfn_pte(0, __pgprot(0)); + } + + if (user) { + pgdp = vcpu->arch.guest_user_mm.pgd; + ptep = kvm_mips_walk_pgd(pgdp, NULL, addr); + if (ptep) { + ptep[0] = pfn_pte(0, __pgprot(0)); + ptep[1] = pfn_pte(0, __pgprot(0)); + } + } +} + +/* + * kvm_mips_flush_gva_{pte,pmd,pud,pgd,pt}. + * Flush a range of guest physical address space from the VM's GPA page tables. + */ + +static bool kvm_mips_flush_gva_pte(pte_t *pte, unsigned long start_gva, + unsigned long end_gva) +{ + int i_min = pte_index(start_gva); + int i_max = pte_index(end_gva); + bool safe_to_remove = (i_min == 0 && i_max == PTRS_PER_PTE - 1); + int i; + + /* + * There's no freeing to do, so there's no point clearing individual + * entries unless only part of the last level page table needs flushing. + */ + if (safe_to_remove) + return true; + + for (i = i_min; i <= i_max; ++i) { + if (!pte_present(pte[i])) + continue; + + set_pte(pte + i, __pte(0)); + } + return false; +} + +static bool kvm_mips_flush_gva_pmd(pmd_t *pmd, unsigned long start_gva, + unsigned long end_gva) +{ + pte_t *pte; + unsigned long end = ~0ul; + int i_min = pmd_index(start_gva); + int i_max = pmd_index(end_gva); + bool safe_to_remove = (i_min == 0 && i_max == PTRS_PER_PMD - 1); + int i; + + for (i = i_min; i <= i_max; ++i, start_gva = 0) { + if (!pmd_present(pmd[i])) + continue; + + pte = pte_offset_kernel(pmd + i, 0); + if (i == i_max) + end = end_gva; + + if (kvm_mips_flush_gva_pte(pte, start_gva, end)) { + pmd_clear(pmd + i); + pte_free_kernel(NULL, pte); + } else { + safe_to_remove = false; + } + } + return safe_to_remove; +} + +static bool kvm_mips_flush_gva_pud(pud_t *pud, unsigned long start_gva, + unsigned long end_gva) +{ + pmd_t *pmd; + unsigned long end = ~0ul; + int i_min = pud_index(start_gva); + int i_max = pud_index(end_gva); + bool safe_to_remove = (i_min == 0 && i_max == PTRS_PER_PUD - 1); + int i; + + for (i = i_min; i <= i_max; ++i, start_gva = 0) { + if (!pud_present(pud[i])) + continue; + + pmd = pmd_offset(pud + i, 0); + if (i == i_max) + end = end_gva; + + if (kvm_mips_flush_gva_pmd(pmd, start_gva, end)) { + pud_clear(pud + i); + pmd_free(NULL, pmd); + } else { + safe_to_remove = false; + } + } + return safe_to_remove; +} + +static bool kvm_mips_flush_gva_pgd(pgd_t *pgd, unsigned long start_gva, + unsigned long end_gva) +{ + p4d_t *p4d; + pud_t *pud; + unsigned long end = ~0ul; + int i_min = pgd_index(start_gva); + int i_max = pgd_index(end_gva); + bool safe_to_remove = (i_min == 0 && i_max == PTRS_PER_PGD - 1); + int i; + + for (i = i_min; i <= i_max; ++i, start_gva = 0) { + if (!pgd_present(pgd[i])) + continue; + + p4d = p4d_offset(pgd, 0); + pud = pud_offset(p4d + i, 0); + if (i == i_max) + end = end_gva; + + if (kvm_mips_flush_gva_pud(pud, start_gva, end)) { + pgd_clear(pgd + i); + pud_free(NULL, pud); + } else { + safe_to_remove = false; + } + } + return safe_to_remove; +} + +void kvm_mips_flush_gva_pt(pgd_t *pgd, enum kvm_mips_flush flags) +{ + if (flags & KMF_GPA) { + /* all of guest virtual address space could be affected */ + if (flags & KMF_KERN) + /* useg, kseg0, seg2/3 */ + kvm_mips_flush_gva_pgd(pgd, 0, 0x7fffffff); + else + /* useg */ + kvm_mips_flush_gva_pgd(pgd, 0, 0x3fffffff); + } else { + /* useg */ + kvm_mips_flush_gva_pgd(pgd, 0, 0x3fffffff); + + /* kseg2/3 */ + if (flags & KMF_KERN) + kvm_mips_flush_gva_pgd(pgd, 0x60000000, 0x7fffffff); + } +} + +static pte_t kvm_mips_gpa_pte_to_gva_unmapped(pte_t pte) +{ + /* + * Don't leak writeable but clean entries from GPA page tables. We don't + * want the normal Linux tlbmod handler to handle dirtying when KVM + * accesses guest memory. + */ + if (!pte_dirty(pte)) + pte = pte_wrprotect(pte); + + return pte; +} + +static pte_t kvm_mips_gpa_pte_to_gva_mapped(pte_t pte, long entrylo) +{ + /* Guest EntryLo overrides host EntryLo */ + if (!(entrylo & ENTRYLO_D)) + pte = pte_mkclean(pte); + + return kvm_mips_gpa_pte_to_gva_unmapped(pte); +} + +#ifdef CONFIG_KVM_MIPS_VZ +int kvm_mips_handle_vz_root_tlb_fault(unsigned long badvaddr, + struct kvm_vcpu *vcpu, + bool write_fault) +{ + int ret; + + ret = kvm_mips_map_page(vcpu, badvaddr, write_fault, NULL, NULL); + if (ret) + return ret; + + /* Invalidate this entry in the TLB */ + return kvm_vz_host_tlb_inv(vcpu, badvaddr); +} +#endif + +/* XXXKYMA: Must be called with interrupts disabled */ +int kvm_mips_handle_kseg0_tlb_fault(unsigned long badvaddr, + struct kvm_vcpu *vcpu, + bool write_fault) +{ + unsigned long gpa; + pte_t pte_gpa[2], *ptep_gva; + int idx; + + if (KVM_GUEST_KSEGX(badvaddr) != KVM_GUEST_KSEG0) { + kvm_err("%s: Invalid BadVaddr: %#lx\n", __func__, badvaddr); + kvm_mips_dump_host_tlbs(); + return -1; + } + + /* Get the GPA page table entry */ + gpa = KVM_GUEST_CPHYSADDR(badvaddr); + idx = (badvaddr >> PAGE_SHIFT) & 1; + if (kvm_mips_map_page(vcpu, gpa, write_fault, &pte_gpa[idx], + &pte_gpa[!idx]) < 0) + return -1; + + /* Get the GVA page table entry */ + ptep_gva = kvm_trap_emul_pte_for_gva(vcpu, badvaddr & ~PAGE_SIZE); + if (!ptep_gva) { + kvm_err("No ptep for gva %lx\n", badvaddr); + return -1; + } + + /* Copy a pair of entries from GPA page table to GVA page table */ + ptep_gva[0] = kvm_mips_gpa_pte_to_gva_unmapped(pte_gpa[0]); + ptep_gva[1] = kvm_mips_gpa_pte_to_gva_unmapped(pte_gpa[1]); + + /* Invalidate this entry in the TLB, guest kernel ASID only */ + kvm_mips_host_tlb_inv(vcpu, badvaddr, false, true); + return 0; +} + +int kvm_mips_handle_mapped_seg_tlb_fault(struct kvm_vcpu *vcpu, + struct kvm_mips_tlb *tlb, + unsigned long gva, + bool write_fault) +{ + struct kvm *kvm = vcpu->kvm; + long tlb_lo[2]; + pte_t pte_gpa[2], *ptep_buddy, *ptep_gva; + unsigned int idx = TLB_LO_IDX(*tlb, gva); + bool kernel = KVM_GUEST_KERNEL_MODE(vcpu); + + tlb_lo[0] = tlb->tlb_lo[0]; + tlb_lo[1] = tlb->tlb_lo[1]; + + /* + * The commpage address must not be mapped to anything else if the guest + * TLB contains entries nearby, or commpage accesses will break. + */ + if (!((gva ^ KVM_GUEST_COMMPAGE_ADDR) & VPN2_MASK & (PAGE_MASK << 1))) + tlb_lo[TLB_LO_IDX(*tlb, KVM_GUEST_COMMPAGE_ADDR)] = 0; + + /* Get the GPA page table entry */ + if (kvm_mips_map_page(vcpu, mips3_tlbpfn_to_paddr(tlb_lo[idx]), + write_fault, &pte_gpa[idx], NULL) < 0) + return -1; + + /* And its GVA buddy's GPA page table entry if it also exists */ + pte_gpa[!idx] = pfn_pte(0, __pgprot(0)); + if (tlb_lo[!idx] & ENTRYLO_V) { + spin_lock(&kvm->mmu_lock); + ptep_buddy = kvm_mips_pte_for_gpa(kvm, NULL, + mips3_tlbpfn_to_paddr(tlb_lo[!idx])); + if (ptep_buddy) + pte_gpa[!idx] = *ptep_buddy; + spin_unlock(&kvm->mmu_lock); + } + + /* Get the GVA page table entry pair */ + ptep_gva = kvm_trap_emul_pte_for_gva(vcpu, gva & ~PAGE_SIZE); + if (!ptep_gva) { + kvm_err("No ptep for gva %lx\n", gva); + return -1; + } + + /* Copy a pair of entries from GPA page table to GVA page table */ + ptep_gva[0] = kvm_mips_gpa_pte_to_gva_mapped(pte_gpa[0], tlb_lo[0]); + ptep_gva[1] = kvm_mips_gpa_pte_to_gva_mapped(pte_gpa[1], tlb_lo[1]); + + /* Invalidate this entry in the TLB, current guest mode ASID only */ + kvm_mips_host_tlb_inv(vcpu, gva, !kernel, kernel); + + kvm_debug("@ %#lx tlb_lo0: 0x%08lx tlb_lo1: 0x%08lx\n", vcpu->arch.pc, + tlb->tlb_lo[0], tlb->tlb_lo[1]); + + return 0; +} + +int kvm_mips_handle_commpage_tlb_fault(unsigned long badvaddr, + struct kvm_vcpu *vcpu) +{ + kvm_pfn_t pfn; + pte_t *ptep; + + ptep = kvm_trap_emul_pte_for_gva(vcpu, badvaddr); + if (!ptep) { + kvm_err("No ptep for commpage %lx\n", badvaddr); + return -1; + } + + pfn = PFN_DOWN(virt_to_phys(vcpu->arch.kseg0_commpage)); + /* Also set valid and dirty, so refill handler doesn't have to */ + *ptep = pte_mkyoung(pte_mkdirty(pfn_pte(pfn, PAGE_SHARED))); + + /* Invalidate this entry in the TLB, guest kernel ASID only */ + kvm_mips_host_tlb_inv(vcpu, badvaddr, false, true); + return 0; +} + +/** + * kvm_mips_migrate_count() - Migrate timer. + * @vcpu: Virtual CPU. + * + * Migrate CP0_Count hrtimer to the current CPU by cancelling and restarting it + * if it was running prior to being cancelled. + * + * Must be called when the VCPU is migrated to a different CPU to ensure that + * timer expiry during guest execution interrupts the guest and causes the + * interrupt to be delivered in a timely manner. + */ +static void kvm_mips_migrate_count(struct kvm_vcpu *vcpu) +{ + if (hrtimer_cancel(&vcpu->arch.comparecount_timer)) + hrtimer_restart(&vcpu->arch.comparecount_timer); +} + +/* Restore ASID once we are scheduled back after preemption */ +void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) +{ + unsigned long flags; + + kvm_debug("%s: vcpu %p, cpu: %d\n", __func__, vcpu, cpu); + + local_irq_save(flags); + + vcpu->cpu = cpu; + if (vcpu->arch.last_sched_cpu != cpu) { + kvm_debug("[%d->%d]KVM VCPU[%d] switch\n", + vcpu->arch.last_sched_cpu, cpu, vcpu->vcpu_id); + /* + * Migrate the timer interrupt to the current CPU so that it + * always interrupts the guest and synchronously triggers a + * guest timer interrupt. + */ + kvm_mips_migrate_count(vcpu); + } + + /* restore guest state to registers */ + kvm_mips_callbacks->vcpu_load(vcpu, cpu); + + local_irq_restore(flags); +} + +/* ASID can change if another task is scheduled during preemption */ +void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu) +{ + unsigned long flags; + int cpu; + + local_irq_save(flags); + + cpu = smp_processor_id(); + vcpu->arch.last_sched_cpu = cpu; + vcpu->cpu = -1; + + /* save guest state in registers */ + kvm_mips_callbacks->vcpu_put(vcpu, cpu); + + local_irq_restore(flags); +} + +/** + * kvm_trap_emul_gva_fault() - Safely attempt to handle a GVA access fault. + * @vcpu: Virtual CPU. + * @gva: Guest virtual address to be accessed. + * @write: True if write attempted (must be dirtied and made writable). + * + * Safely attempt to handle a GVA fault, mapping GVA pages if necessary, and + * dirtying the page if @write so that guest instructions can be modified. + * + * Returns: KVM_MIPS_MAPPED on success. + * KVM_MIPS_GVA if bad guest virtual address. + * KVM_MIPS_GPA if bad guest physical address. + * KVM_MIPS_TLB if guest TLB not present. + * KVM_MIPS_TLBINV if guest TLB present but not valid. + * KVM_MIPS_TLBMOD if guest TLB read only. + */ +enum kvm_mips_fault_result kvm_trap_emul_gva_fault(struct kvm_vcpu *vcpu, + unsigned long gva, + bool write) +{ + struct mips_coproc *cop0 = vcpu->arch.cop0; + struct kvm_mips_tlb *tlb; + int index; + + if (KVM_GUEST_KSEGX(gva) == KVM_GUEST_KSEG0) { + if (kvm_mips_handle_kseg0_tlb_fault(gva, vcpu, write) < 0) + return KVM_MIPS_GPA; + } else if ((KVM_GUEST_KSEGX(gva) < KVM_GUEST_KSEG0) || + KVM_GUEST_KSEGX(gva) == KVM_GUEST_KSEG23) { + /* Address should be in the guest TLB */ + index = kvm_mips_guest_tlb_lookup(vcpu, (gva & VPN2_MASK) | + (kvm_read_c0_guest_entryhi(cop0) & KVM_ENTRYHI_ASID)); + if (index < 0) + return KVM_MIPS_TLB; + tlb = &vcpu->arch.guest_tlb[index]; + + /* Entry should be valid, and dirty for writes */ + if (!TLB_IS_VALID(*tlb, gva)) + return KVM_MIPS_TLBINV; + if (write && !TLB_IS_DIRTY(*tlb, gva)) + return KVM_MIPS_TLBMOD; + + if (kvm_mips_handle_mapped_seg_tlb_fault(vcpu, tlb, gva, write)) + return KVM_MIPS_GPA; + } else { + return KVM_MIPS_GVA; + } + + return KVM_MIPS_MAPPED; +} + +int kvm_get_inst(u32 *opc, struct kvm_vcpu *vcpu, u32 *out) +{ + int err; + + if (WARN(IS_ENABLED(CONFIG_KVM_MIPS_VZ), + "Expect BadInstr/BadInstrP registers to be used with VZ\n")) + return -EINVAL; + +retry: + kvm_trap_emul_gva_lockless_begin(vcpu); + err = get_user(*out, opc); + kvm_trap_emul_gva_lockless_end(vcpu); + + if (unlikely(err)) { + /* + * Try to handle the fault, maybe we just raced with a GVA + * invalidation. + */ + err = kvm_trap_emul_gva_fault(vcpu, (unsigned long)opc, + false); + if (unlikely(err)) { + kvm_err("%s: illegal address: %p\n", + __func__, opc); + return -EFAULT; + } + + /* Hopefully it'll work now */ + goto retry; + } + return 0; +} |