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Diffstat (limited to '')
| -rw-r--r-- | arch/x86/kernel/kvm.c | 1158 |
1 files changed, 1158 insertions, 0 deletions
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c new file mode 100644 index 000000000..796e2f9e8 --- /dev/null +++ b/arch/x86/kernel/kvm.c @@ -0,0 +1,1158 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * KVM paravirt_ops implementation + * + * Copyright (C) 2007, Red Hat, Inc., Ingo Molnar <mingo@redhat.com> + * Copyright IBM Corporation, 2007 + * Authors: Anthony Liguori <aliguori@us.ibm.com> + */ + +#define pr_fmt(fmt) "kvm-guest: " fmt + +#include <linux/context_tracking.h> +#include <linux/init.h> +#include <linux/irq.h> +#include <linux/kernel.h> +#include <linux/kvm_para.h> +#include <linux/cpu.h> +#include <linux/mm.h> +#include <linux/highmem.h> +#include <linux/hardirq.h> +#include <linux/notifier.h> +#include <linux/reboot.h> +#include <linux/hash.h> +#include <linux/sched.h> +#include <linux/slab.h> +#include <linux/kprobes.h> +#include <linux/nmi.h> +#include <linux/swait.h> +#include <linux/syscore_ops.h> +#include <linux/cc_platform.h> +#include <linux/efi.h> +#include <asm/timer.h> +#include <asm/cpu.h> +#include <asm/traps.h> +#include <asm/desc.h> +#include <asm/tlbflush.h> +#include <asm/apic.h> +#include <asm/apicdef.h> +#include <asm/hypervisor.h> +#include <asm/tlb.h> +#include <asm/cpuidle_haltpoll.h> +#include <asm/ptrace.h> +#include <asm/reboot.h> +#include <asm/svm.h> +#include <asm/e820/api.h> + +DEFINE_STATIC_KEY_FALSE(kvm_async_pf_enabled); + +static int kvmapf = 1; + +static int __init parse_no_kvmapf(char *arg) +{ + kvmapf = 0; + return 0; +} + +early_param("no-kvmapf", parse_no_kvmapf); + +static int steal_acc = 1; +static int __init parse_no_stealacc(char *arg) +{ + steal_acc = 0; + return 0; +} + +early_param("no-steal-acc", parse_no_stealacc); + +static DEFINE_PER_CPU_DECRYPTED(struct kvm_vcpu_pv_apf_data, apf_reason) __aligned(64); +DEFINE_PER_CPU_DECRYPTED(struct kvm_steal_time, steal_time) __aligned(64) __visible; +static int has_steal_clock = 0; + +static int has_guest_poll = 0; +/* + * No need for any "IO delay" on KVM + */ +static void kvm_io_delay(void) +{ +} + +#define KVM_TASK_SLEEP_HASHBITS 8 +#define KVM_TASK_SLEEP_HASHSIZE (1<<KVM_TASK_SLEEP_HASHBITS) + +struct kvm_task_sleep_node { + struct hlist_node link; + struct swait_queue_head wq; + u32 token; + int cpu; +}; + +static struct kvm_task_sleep_head { + raw_spinlock_t lock; + struct hlist_head list; +} async_pf_sleepers[KVM_TASK_SLEEP_HASHSIZE]; + +static struct kvm_task_sleep_node *_find_apf_task(struct kvm_task_sleep_head *b, + u32 token) +{ + struct hlist_node *p; + + hlist_for_each(p, &b->list) { + struct kvm_task_sleep_node *n = + hlist_entry(p, typeof(*n), link); + if (n->token == token) + return n; + } + + return NULL; +} + +static bool kvm_async_pf_queue_task(u32 token, struct kvm_task_sleep_node *n) +{ + u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS); + struct kvm_task_sleep_head *b = &async_pf_sleepers[key]; + struct kvm_task_sleep_node *e; + + raw_spin_lock(&b->lock); + e = _find_apf_task(b, token); + if (e) { + /* dummy entry exist -> wake up was delivered ahead of PF */ + hlist_del(&e->link); + raw_spin_unlock(&b->lock); + kfree(e); + return false; + } + + n->token = token; + n->cpu = smp_processor_id(); + init_swait_queue_head(&n->wq); + hlist_add_head(&n->link, &b->list); + raw_spin_unlock(&b->lock); + return true; +} + +/* + * kvm_async_pf_task_wait_schedule - Wait for pagefault to be handled + * @token: Token to identify the sleep node entry + * + * Invoked from the async pagefault handling code or from the VM exit page + * fault handler. In both cases RCU is watching. + */ +void kvm_async_pf_task_wait_schedule(u32 token) +{ + struct kvm_task_sleep_node n; + DECLARE_SWAITQUEUE(wait); + + lockdep_assert_irqs_disabled(); + + if (!kvm_async_pf_queue_task(token, &n)) + return; + + for (;;) { + prepare_to_swait_exclusive(&n.wq, &wait, TASK_UNINTERRUPTIBLE); + if (hlist_unhashed(&n.link)) + break; + + local_irq_enable(); + schedule(); + local_irq_disable(); + } + finish_swait(&n.wq, &wait); +} +EXPORT_SYMBOL_GPL(kvm_async_pf_task_wait_schedule); + +static void apf_task_wake_one(struct kvm_task_sleep_node *n) +{ + hlist_del_init(&n->link); + if (swq_has_sleeper(&n->wq)) + swake_up_one(&n->wq); +} + +static void apf_task_wake_all(void) +{ + int i; + + for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++) { + struct kvm_task_sleep_head *b = &async_pf_sleepers[i]; + struct kvm_task_sleep_node *n; + struct hlist_node *p, *next; + + raw_spin_lock(&b->lock); + hlist_for_each_safe(p, next, &b->list) { + n = hlist_entry(p, typeof(*n), link); + if (n->cpu == smp_processor_id()) + apf_task_wake_one(n); + } + raw_spin_unlock(&b->lock); + } +} + +void kvm_async_pf_task_wake(u32 token) +{ + u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS); + struct kvm_task_sleep_head *b = &async_pf_sleepers[key]; + struct kvm_task_sleep_node *n, *dummy = NULL; + + if (token == ~0) { + apf_task_wake_all(); + return; + } + +again: + raw_spin_lock(&b->lock); + n = _find_apf_task(b, token); + if (!n) { + /* + * Async #PF not yet handled, add a dummy entry for the token. + * Allocating the token must be down outside of the raw lock + * as the allocator is preemptible on PREEMPT_RT kernels. + */ + if (!dummy) { + raw_spin_unlock(&b->lock); + dummy = kzalloc(sizeof(*dummy), GFP_ATOMIC); + + /* + * Continue looping on allocation failure, eventually + * the async #PF will be handled and allocating a new + * node will be unnecessary. + */ + if (!dummy) + cpu_relax(); + + /* + * Recheck for async #PF completion before enqueueing + * the dummy token to avoid duplicate list entries. + */ + goto again; + } + dummy->token = token; + dummy->cpu = smp_processor_id(); + init_swait_queue_head(&dummy->wq); + hlist_add_head(&dummy->link, &b->list); + dummy = NULL; + } else { + apf_task_wake_one(n); + } + raw_spin_unlock(&b->lock); + + /* A dummy token might be allocated and ultimately not used. */ + kfree(dummy); +} +EXPORT_SYMBOL_GPL(kvm_async_pf_task_wake); + +noinstr u32 kvm_read_and_reset_apf_flags(void) +{ + u32 flags = 0; + + if (__this_cpu_read(apf_reason.enabled)) { + flags = __this_cpu_read(apf_reason.flags); + __this_cpu_write(apf_reason.flags, 0); + } + + return flags; +} +EXPORT_SYMBOL_GPL(kvm_read_and_reset_apf_flags); + +noinstr bool __kvm_handle_async_pf(struct pt_regs *regs, u32 token) +{ + u32 flags = kvm_read_and_reset_apf_flags(); + irqentry_state_t state; + + if (!flags) + return false; + + state = irqentry_enter(regs); + instrumentation_begin(); + + /* + * If the host managed to inject an async #PF into an interrupt + * disabled region, then die hard as this is not going to end well + * and the host side is seriously broken. + */ + if (unlikely(!(regs->flags & X86_EFLAGS_IF))) + panic("Host injected async #PF in interrupt disabled region\n"); + + if (flags & KVM_PV_REASON_PAGE_NOT_PRESENT) { + if (unlikely(!(user_mode(regs)))) + panic("Host injected async #PF in kernel mode\n"); + /* Page is swapped out by the host. */ + kvm_async_pf_task_wait_schedule(token); + } else { + WARN_ONCE(1, "Unexpected async PF flags: %x\n", flags); + } + + instrumentation_end(); + irqentry_exit(regs, state); + return true; +} + +DEFINE_IDTENTRY_SYSVEC(sysvec_kvm_asyncpf_interrupt) +{ + struct pt_regs *old_regs = set_irq_regs(regs); + u32 token; + + ack_APIC_irq(); + + inc_irq_stat(irq_hv_callback_count); + + if (__this_cpu_read(apf_reason.enabled)) { + token = __this_cpu_read(apf_reason.token); + kvm_async_pf_task_wake(token); + __this_cpu_write(apf_reason.token, 0); + wrmsrl(MSR_KVM_ASYNC_PF_ACK, 1); + } + + set_irq_regs(old_regs); +} + +static void __init paravirt_ops_setup(void) +{ + pv_info.name = "KVM"; + + if (kvm_para_has_feature(KVM_FEATURE_NOP_IO_DELAY)) + pv_ops.cpu.io_delay = kvm_io_delay; + +#ifdef CONFIG_X86_IO_APIC + no_timer_check = 1; +#endif +} + +static void kvm_register_steal_time(void) +{ + int cpu = smp_processor_id(); + struct kvm_steal_time *st = &per_cpu(steal_time, cpu); + + if (!has_steal_clock) + return; + + wrmsrl(MSR_KVM_STEAL_TIME, (slow_virt_to_phys(st) | KVM_MSR_ENABLED)); + pr_debug("stealtime: cpu %d, msr %llx\n", cpu, + (unsigned long long) slow_virt_to_phys(st)); +} + +static DEFINE_PER_CPU_DECRYPTED(unsigned long, kvm_apic_eoi) = KVM_PV_EOI_DISABLED; + +static notrace void kvm_guest_apic_eoi_write(u32 reg, u32 val) +{ + /** + * This relies on __test_and_clear_bit to modify the memory + * in a way that is atomic with respect to the local CPU. + * The hypervisor only accesses this memory from the local CPU so + * there's no need for lock or memory barriers. + * An optimization barrier is implied in apic write. + */ + if (__test_and_clear_bit(KVM_PV_EOI_BIT, this_cpu_ptr(&kvm_apic_eoi))) + return; + apic->native_eoi_write(APIC_EOI, APIC_EOI_ACK); +} + +static void kvm_guest_cpu_init(void) +{ + if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_INT) && kvmapf) { + u64 pa = slow_virt_to_phys(this_cpu_ptr(&apf_reason)); + + WARN_ON_ONCE(!static_branch_likely(&kvm_async_pf_enabled)); + + pa = slow_virt_to_phys(this_cpu_ptr(&apf_reason)); + pa |= KVM_ASYNC_PF_ENABLED | KVM_ASYNC_PF_DELIVERY_AS_INT; + + if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_VMEXIT)) + pa |= KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT; + + wrmsrl(MSR_KVM_ASYNC_PF_INT, HYPERVISOR_CALLBACK_VECTOR); + + wrmsrl(MSR_KVM_ASYNC_PF_EN, pa); + __this_cpu_write(apf_reason.enabled, 1); + pr_debug("setup async PF for cpu %d\n", smp_processor_id()); + } + + if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) { + unsigned long pa; + + /* Size alignment is implied but just to make it explicit. */ + BUILD_BUG_ON(__alignof__(kvm_apic_eoi) < 4); + __this_cpu_write(kvm_apic_eoi, 0); + pa = slow_virt_to_phys(this_cpu_ptr(&kvm_apic_eoi)) + | KVM_MSR_ENABLED; + wrmsrl(MSR_KVM_PV_EOI_EN, pa); + } + + if (has_steal_clock) + kvm_register_steal_time(); +} + +static void kvm_pv_disable_apf(void) +{ + if (!__this_cpu_read(apf_reason.enabled)) + return; + + wrmsrl(MSR_KVM_ASYNC_PF_EN, 0); + __this_cpu_write(apf_reason.enabled, 0); + + pr_debug("disable async PF for cpu %d\n", smp_processor_id()); +} + +static void kvm_disable_steal_time(void) +{ + if (!has_steal_clock) + return; + + wrmsr(MSR_KVM_STEAL_TIME, 0, 0); +} + +static u64 kvm_steal_clock(int cpu) +{ + u64 steal; + struct kvm_steal_time *src; + int version; + + src = &per_cpu(steal_time, cpu); + do { + version = src->version; + virt_rmb(); + steal = src->steal; + virt_rmb(); + } while ((version & 1) || (version != src->version)); + + return steal; +} + +static inline void __set_percpu_decrypted(void *ptr, unsigned long size) +{ + early_set_memory_decrypted((unsigned long) ptr, size); +} + +/* + * Iterate through all possible CPUs and map the memory region pointed + * by apf_reason, steal_time and kvm_apic_eoi as decrypted at once. + * + * Note: we iterate through all possible CPUs to ensure that CPUs + * hotplugged will have their per-cpu variable already mapped as + * decrypted. + */ +static void __init sev_map_percpu_data(void) +{ + int cpu; + + if (!cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT)) + return; + + for_each_possible_cpu(cpu) { + __set_percpu_decrypted(&per_cpu(apf_reason, cpu), sizeof(apf_reason)); + __set_percpu_decrypted(&per_cpu(steal_time, cpu), sizeof(steal_time)); + __set_percpu_decrypted(&per_cpu(kvm_apic_eoi, cpu), sizeof(kvm_apic_eoi)); + } +} + +static void kvm_guest_cpu_offline(bool shutdown) +{ + kvm_disable_steal_time(); + if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) + wrmsrl(MSR_KVM_PV_EOI_EN, 0); + if (kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL)) + wrmsrl(MSR_KVM_MIGRATION_CONTROL, 0); + kvm_pv_disable_apf(); + if (!shutdown) + apf_task_wake_all(); + kvmclock_disable(); +} + +static int kvm_cpu_online(unsigned int cpu) +{ + unsigned long flags; + + local_irq_save(flags); + kvm_guest_cpu_init(); + local_irq_restore(flags); + return 0; +} + +#ifdef CONFIG_SMP + +static DEFINE_PER_CPU(cpumask_var_t, __pv_cpu_mask); + +static bool pv_tlb_flush_supported(void) +{ + return (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) && + !kvm_para_has_hint(KVM_HINTS_REALTIME) && + kvm_para_has_feature(KVM_FEATURE_STEAL_TIME) && + !boot_cpu_has(X86_FEATURE_MWAIT) && + (num_possible_cpus() != 1)); +} + +static bool pv_ipi_supported(void) +{ + return (kvm_para_has_feature(KVM_FEATURE_PV_SEND_IPI) && + (num_possible_cpus() != 1)); +} + +static bool pv_sched_yield_supported(void) +{ + return (kvm_para_has_feature(KVM_FEATURE_PV_SCHED_YIELD) && + !kvm_para_has_hint(KVM_HINTS_REALTIME) && + kvm_para_has_feature(KVM_FEATURE_STEAL_TIME) && + !boot_cpu_has(X86_FEATURE_MWAIT) && + (num_possible_cpus() != 1)); +} + +#define KVM_IPI_CLUSTER_SIZE (2 * BITS_PER_LONG) + +static void __send_ipi_mask(const struct cpumask *mask, int vector) +{ + unsigned long flags; + int cpu, apic_id, icr; + int min = 0, max = 0; +#ifdef CONFIG_X86_64 + __uint128_t ipi_bitmap = 0; +#else + u64 ipi_bitmap = 0; +#endif + long ret; + + if (cpumask_empty(mask)) + return; + + local_irq_save(flags); + + switch (vector) { + default: + icr = APIC_DM_FIXED | vector; + break; + case NMI_VECTOR: + icr = APIC_DM_NMI; + break; + } + + for_each_cpu(cpu, mask) { + apic_id = per_cpu(x86_cpu_to_apicid, cpu); + if (!ipi_bitmap) { + min = max = apic_id; + } else if (apic_id < min && max - apic_id < KVM_IPI_CLUSTER_SIZE) { + ipi_bitmap <<= min - apic_id; + min = apic_id; + } else if (apic_id > min && apic_id < min + KVM_IPI_CLUSTER_SIZE) { + max = apic_id < max ? max : apic_id; + } else { + ret = kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap, + (unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr); + WARN_ONCE(ret < 0, "kvm-guest: failed to send PV IPI: %ld", + ret); + min = max = apic_id; + ipi_bitmap = 0; + } + __set_bit(apic_id - min, (unsigned long *)&ipi_bitmap); + } + + if (ipi_bitmap) { + ret = kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap, + (unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr); + WARN_ONCE(ret < 0, "kvm-guest: failed to send PV IPI: %ld", + ret); + } + + local_irq_restore(flags); +} + +static void kvm_send_ipi_mask(const struct cpumask *mask, int vector) +{ + __send_ipi_mask(mask, vector); +} + +static void kvm_send_ipi_mask_allbutself(const struct cpumask *mask, int vector) +{ + unsigned int this_cpu = smp_processor_id(); + struct cpumask *new_mask = this_cpu_cpumask_var_ptr(__pv_cpu_mask); + const struct cpumask *local_mask; + + cpumask_copy(new_mask, mask); + cpumask_clear_cpu(this_cpu, new_mask); + local_mask = new_mask; + __send_ipi_mask(local_mask, vector); +} + +static int __init setup_efi_kvm_sev_migration(void) +{ + efi_char16_t efi_sev_live_migration_enabled[] = L"SevLiveMigrationEnabled"; + efi_guid_t efi_variable_guid = AMD_SEV_MEM_ENCRYPT_GUID; + efi_status_t status; + unsigned long size; + bool enabled; + + if (!cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT) || + !kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL)) + return 0; + + if (!efi_enabled(EFI_BOOT)) + return 0; + + if (!efi_enabled(EFI_RUNTIME_SERVICES)) { + pr_info("%s : EFI runtime services are not enabled\n", __func__); + return 0; + } + + size = sizeof(enabled); + + /* Get variable contents into buffer */ + status = efi.get_variable(efi_sev_live_migration_enabled, + &efi_variable_guid, NULL, &size, &enabled); + + if (status == EFI_NOT_FOUND) { + pr_info("%s : EFI live migration variable not found\n", __func__); + return 0; + } + + if (status != EFI_SUCCESS) { + pr_info("%s : EFI variable retrieval failed\n", __func__); + return 0; + } + + if (enabled == 0) { + pr_info("%s: live migration disabled in EFI\n", __func__); + return 0; + } + + pr_info("%s : live migration enabled in EFI\n", __func__); + wrmsrl(MSR_KVM_MIGRATION_CONTROL, KVM_MIGRATION_READY); + + return 1; +} + +late_initcall(setup_efi_kvm_sev_migration); + +/* + * Set the IPI entry points + */ +static void kvm_setup_pv_ipi(void) +{ + apic->send_IPI_mask = kvm_send_ipi_mask; + apic->send_IPI_mask_allbutself = kvm_send_ipi_mask_allbutself; + pr_info("setup PV IPIs\n"); +} + +static void kvm_smp_send_call_func_ipi(const struct cpumask *mask) +{ + int cpu; + + native_send_call_func_ipi(mask); + + /* Make sure other vCPUs get a chance to run if they need to. */ + for_each_cpu(cpu, mask) { + if (!idle_cpu(cpu) && vcpu_is_preempted(cpu)) { + kvm_hypercall1(KVM_HC_SCHED_YIELD, per_cpu(x86_cpu_to_apicid, cpu)); + break; + } + } +} + +static void kvm_flush_tlb_multi(const struct cpumask *cpumask, + const struct flush_tlb_info *info) +{ + u8 state; + int cpu; + struct kvm_steal_time *src; + struct cpumask *flushmask = this_cpu_cpumask_var_ptr(__pv_cpu_mask); + + cpumask_copy(flushmask, cpumask); + /* + * We have to call flush only on online vCPUs. And + * queue flush_on_enter for pre-empted vCPUs + */ + for_each_cpu(cpu, flushmask) { + /* + * The local vCPU is never preempted, so we do not explicitly + * skip check for local vCPU - it will never be cleared from + * flushmask. + */ + src = &per_cpu(steal_time, cpu); + state = READ_ONCE(src->preempted); + if ((state & KVM_VCPU_PREEMPTED)) { + if (try_cmpxchg(&src->preempted, &state, + state | KVM_VCPU_FLUSH_TLB)) + __cpumask_clear_cpu(cpu, flushmask); + } + } + + native_flush_tlb_multi(flushmask, info); +} + +static __init int kvm_alloc_cpumask(void) +{ + int cpu; + + if (!kvm_para_available() || nopv) + return 0; + + if (pv_tlb_flush_supported() || pv_ipi_supported()) + for_each_possible_cpu(cpu) { + zalloc_cpumask_var_node(per_cpu_ptr(&__pv_cpu_mask, cpu), + GFP_KERNEL, cpu_to_node(cpu)); + } + + return 0; +} +arch_initcall(kvm_alloc_cpumask); + +static void __init kvm_smp_prepare_boot_cpu(void) +{ + /* + * Map the per-cpu variables as decrypted before kvm_guest_cpu_init() + * shares the guest physical address with the hypervisor. + */ + sev_map_percpu_data(); + + kvm_guest_cpu_init(); + native_smp_prepare_boot_cpu(); + kvm_spinlock_init(); +} + +static int kvm_cpu_down_prepare(unsigned int cpu) +{ + unsigned long flags; + + local_irq_save(flags); + kvm_guest_cpu_offline(false); + local_irq_restore(flags); + return 0; +} + +#endif + +static int kvm_suspend(void) +{ + u64 val = 0; + + kvm_guest_cpu_offline(false); + +#ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL + if (kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL)) + rdmsrl(MSR_KVM_POLL_CONTROL, val); + has_guest_poll = !(val & 1); +#endif + return 0; +} + +static void kvm_resume(void) +{ + kvm_cpu_online(raw_smp_processor_id()); + +#ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL + if (kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL) && has_guest_poll) + wrmsrl(MSR_KVM_POLL_CONTROL, 0); +#endif +} + +static struct syscore_ops kvm_syscore_ops = { + .suspend = kvm_suspend, + .resume = kvm_resume, +}; + +static void kvm_pv_guest_cpu_reboot(void *unused) +{ + kvm_guest_cpu_offline(true); +} + +static int kvm_pv_reboot_notify(struct notifier_block *nb, + unsigned long code, void *unused) +{ + if (code == SYS_RESTART) + on_each_cpu(kvm_pv_guest_cpu_reboot, NULL, 1); + return NOTIFY_DONE; +} + +static struct notifier_block kvm_pv_reboot_nb = { + .notifier_call = kvm_pv_reboot_notify, +}; + +/* + * After a PV feature is registered, the host will keep writing to the + * registered memory location. If the guest happens to shutdown, this memory + * won't be valid. In cases like kexec, in which you install a new kernel, this + * means a random memory location will be kept being written. + */ +#ifdef CONFIG_KEXEC_CORE +static void kvm_crash_shutdown(struct pt_regs *regs) +{ + kvm_guest_cpu_offline(true); + native_machine_crash_shutdown(regs); +} +#endif + +#if defined(CONFIG_X86_32) || !defined(CONFIG_SMP) +bool __kvm_vcpu_is_preempted(long cpu); + +__visible bool __kvm_vcpu_is_preempted(long cpu) +{ + struct kvm_steal_time *src = &per_cpu(steal_time, cpu); + + return !!(src->preempted & KVM_VCPU_PREEMPTED); +} +PV_CALLEE_SAVE_REGS_THUNK(__kvm_vcpu_is_preempted); + +#else + +#include <asm/asm-offsets.h> + +extern bool __raw_callee_save___kvm_vcpu_is_preempted(long); + +/* + * Hand-optimize version for x86-64 to avoid 8 64-bit register saving and + * restoring to/from the stack. + */ +asm( +".pushsection .text;" +".global __raw_callee_save___kvm_vcpu_is_preempted;" +".type __raw_callee_save___kvm_vcpu_is_preempted, @function;" +"__raw_callee_save___kvm_vcpu_is_preempted:" +ASM_ENDBR +"movq __per_cpu_offset(,%rdi,8), %rax;" +"cmpb $0, " __stringify(KVM_STEAL_TIME_preempted) "+steal_time(%rax);" +"setne %al;" +ASM_RET +".size __raw_callee_save___kvm_vcpu_is_preempted, .-__raw_callee_save___kvm_vcpu_is_preempted;" +".popsection"); + +#endif + +static void __init kvm_guest_init(void) +{ + int i; + + paravirt_ops_setup(); + register_reboot_notifier(&kvm_pv_reboot_nb); + for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++) + raw_spin_lock_init(&async_pf_sleepers[i].lock); + + if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) { + has_steal_clock = 1; + static_call_update(pv_steal_clock, kvm_steal_clock); + + pv_ops.lock.vcpu_is_preempted = + PV_CALLEE_SAVE(__kvm_vcpu_is_preempted); + } + + if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) + apic_set_eoi_write(kvm_guest_apic_eoi_write); + + if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_INT) && kvmapf) { + static_branch_enable(&kvm_async_pf_enabled); + alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR, asm_sysvec_kvm_asyncpf_interrupt); + } + +#ifdef CONFIG_SMP + if (pv_tlb_flush_supported()) { + pv_ops.mmu.flush_tlb_multi = kvm_flush_tlb_multi; + pv_ops.mmu.tlb_remove_table = tlb_remove_table; + pr_info("KVM setup pv remote TLB flush\n"); + } + + smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu; + if (pv_sched_yield_supported()) { + smp_ops.send_call_func_ipi = kvm_smp_send_call_func_ipi; + pr_info("setup PV sched yield\n"); + } + if (cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "x86/kvm:online", + kvm_cpu_online, kvm_cpu_down_prepare) < 0) + pr_err("failed to install cpu hotplug callbacks\n"); +#else + sev_map_percpu_data(); + kvm_guest_cpu_init(); +#endif + +#ifdef CONFIG_KEXEC_CORE + machine_ops.crash_shutdown = kvm_crash_shutdown; +#endif + + register_syscore_ops(&kvm_syscore_ops); + + /* + * Hard lockup detection is enabled by default. Disable it, as guests + * can get false positives too easily, for example if the host is + * overcommitted. + */ + hardlockup_detector_disable(); +} + +static noinline uint32_t __kvm_cpuid_base(void) +{ + if (boot_cpu_data.cpuid_level < 0) + return 0; /* So we don't blow up on old processors */ + + if (boot_cpu_has(X86_FEATURE_HYPERVISOR)) + return hypervisor_cpuid_base(KVM_SIGNATURE, 0); + + return 0; +} + +static inline uint32_t kvm_cpuid_base(void) +{ + static int kvm_cpuid_base = -1; + + if (kvm_cpuid_base == -1) + kvm_cpuid_base = __kvm_cpuid_base(); + + return kvm_cpuid_base; +} + +bool kvm_para_available(void) +{ + return kvm_cpuid_base() != 0; +} +EXPORT_SYMBOL_GPL(kvm_para_available); + +unsigned int kvm_arch_para_features(void) +{ + return cpuid_eax(kvm_cpuid_base() | KVM_CPUID_FEATURES); +} + +unsigned int kvm_arch_para_hints(void) +{ + return cpuid_edx(kvm_cpuid_base() | KVM_CPUID_FEATURES); +} +EXPORT_SYMBOL_GPL(kvm_arch_para_hints); + +static uint32_t __init kvm_detect(void) +{ + return kvm_cpuid_base(); +} + +static void __init kvm_apic_init(void) +{ +#ifdef CONFIG_SMP + if (pv_ipi_supported()) + kvm_setup_pv_ipi(); +#endif +} + +static bool __init kvm_msi_ext_dest_id(void) +{ + return kvm_para_has_feature(KVM_FEATURE_MSI_EXT_DEST_ID); +} + +static void kvm_sev_hc_page_enc_status(unsigned long pfn, int npages, bool enc) +{ + kvm_sev_hypercall3(KVM_HC_MAP_GPA_RANGE, pfn << PAGE_SHIFT, npages, + KVM_MAP_GPA_RANGE_ENC_STAT(enc) | KVM_MAP_GPA_RANGE_PAGE_SZ_4K); +} + +static void __init kvm_init_platform(void) +{ + if (cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT) && + kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL)) { + unsigned long nr_pages; + int i; + + pv_ops.mmu.notify_page_enc_status_changed = + kvm_sev_hc_page_enc_status; + + /* + * Reset the host's shared pages list related to kernel + * specific page encryption status settings before we load a + * new kernel by kexec. Reset the page encryption status + * during early boot intead of just before kexec to avoid SMP + * races during kvm_pv_guest_cpu_reboot(). + * NOTE: We cannot reset the complete shared pages list + * here as we need to retain the UEFI/OVMF firmware + * specific settings. + */ + + for (i = 0; i < e820_table->nr_entries; i++) { + struct e820_entry *entry = &e820_table->entries[i]; + + if (entry->type != E820_TYPE_RAM) + continue; + + nr_pages = DIV_ROUND_UP(entry->size, PAGE_SIZE); + + kvm_sev_hypercall3(KVM_HC_MAP_GPA_RANGE, entry->addr, + nr_pages, + KVM_MAP_GPA_RANGE_ENCRYPTED | KVM_MAP_GPA_RANGE_PAGE_SZ_4K); + } + + /* + * Ensure that _bss_decrypted section is marked as decrypted in the + * shared pages list. + */ + early_set_mem_enc_dec_hypercall((unsigned long)__start_bss_decrypted, + __end_bss_decrypted - __start_bss_decrypted, 0); + + /* + * If not booted using EFI, enable Live migration support. + */ + if (!efi_enabled(EFI_BOOT)) + wrmsrl(MSR_KVM_MIGRATION_CONTROL, + KVM_MIGRATION_READY); + } + kvmclock_init(); + x86_platform.apic_post_init = kvm_apic_init; +} + +#if defined(CONFIG_AMD_MEM_ENCRYPT) +static void kvm_sev_es_hcall_prepare(struct ghcb *ghcb, struct pt_regs *regs) +{ + /* RAX and CPL are already in the GHCB */ + ghcb_set_rbx(ghcb, regs->bx); + ghcb_set_rcx(ghcb, regs->cx); + ghcb_set_rdx(ghcb, regs->dx); + ghcb_set_rsi(ghcb, regs->si); +} + +static bool kvm_sev_es_hcall_finish(struct ghcb *ghcb, struct pt_regs *regs) +{ + /* No checking of the return state needed */ + return true; +} +#endif + +const __initconst struct hypervisor_x86 x86_hyper_kvm = { + .name = "KVM", + .detect = kvm_detect, + .type = X86_HYPER_KVM, + .init.guest_late_init = kvm_guest_init, + .init.x2apic_available = kvm_para_available, + .init.msi_ext_dest_id = kvm_msi_ext_dest_id, + .init.init_platform = kvm_init_platform, +#if defined(CONFIG_AMD_MEM_ENCRYPT) + .runtime.sev_es_hcall_prepare = kvm_sev_es_hcall_prepare, + .runtime.sev_es_hcall_finish = kvm_sev_es_hcall_finish, +#endif +}; + +static __init int activate_jump_labels(void) +{ + if (has_steal_clock) { + static_key_slow_inc(¶virt_steal_enabled); + if (steal_acc) + static_key_slow_inc(¶virt_steal_rq_enabled); + } + + return 0; +} +arch_initcall(activate_jump_labels); + +#ifdef CONFIG_PARAVIRT_SPINLOCKS + +/* Kick a cpu by its apicid. Used to wake up a halted vcpu */ +static void kvm_kick_cpu(int cpu) +{ + int apicid; + unsigned long flags = 0; + + apicid = per_cpu(x86_cpu_to_apicid, cpu); + kvm_hypercall2(KVM_HC_KICK_CPU, flags, apicid); +} + +#include <asm/qspinlock.h> + +static void kvm_wait(u8 *ptr, u8 val) +{ + if (in_nmi()) + return; + + /* + * halt until it's our turn and kicked. Note that we do safe halt + * for irq enabled case to avoid hang when lock info is overwritten + * in irq spinlock slowpath and no spurious interrupt occur to save us. + */ + if (irqs_disabled()) { + if (READ_ONCE(*ptr) == val) + halt(); + } else { + local_irq_disable(); + + /* safe_halt() will enable IRQ */ + if (READ_ONCE(*ptr) == val) + safe_halt(); + else + local_irq_enable(); + } +} + +/* + * Setup pv_lock_ops to exploit KVM_FEATURE_PV_UNHALT if present. + */ +void __init kvm_spinlock_init(void) +{ + /* + * In case host doesn't support KVM_FEATURE_PV_UNHALT there is still an + * advantage of keeping virt_spin_lock_key enabled: virt_spin_lock() is + * preferred over native qspinlock when vCPU is preempted. + */ + if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT)) { + pr_info("PV spinlocks disabled, no host support\n"); + return; + } + + /* + * Disable PV spinlocks and use native qspinlock when dedicated pCPUs + * are available. + */ + if (kvm_para_has_hint(KVM_HINTS_REALTIME)) { + pr_info("PV spinlocks disabled with KVM_HINTS_REALTIME hints\n"); + goto out; + } + + if (num_possible_cpus() == 1) { + pr_info("PV spinlocks disabled, single CPU\n"); + goto out; + } + + if (nopvspin) { + pr_info("PV spinlocks disabled, forced by \"nopvspin\" parameter\n"); + goto out; + } + + pr_info("PV spinlocks enabled\n"); + + __pv_init_lock_hash(); + pv_ops.lock.queued_spin_lock_slowpath = __pv_queued_spin_lock_slowpath; + pv_ops.lock.queued_spin_unlock = + PV_CALLEE_SAVE(__pv_queued_spin_unlock); + pv_ops.lock.wait = kvm_wait; + pv_ops.lock.kick = kvm_kick_cpu; + + /* + * When PV spinlock is enabled which is preferred over + * virt_spin_lock(), virt_spin_lock_key's value is meaningless. + * Just disable it anyway. + */ +out: + static_branch_disable(&virt_spin_lock_key); +} + +#endif /* CONFIG_PARAVIRT_SPINLOCKS */ + +#ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL + +static void kvm_disable_host_haltpoll(void *i) +{ + wrmsrl(MSR_KVM_POLL_CONTROL, 0); +} + +static void kvm_enable_host_haltpoll(void *i) +{ + wrmsrl(MSR_KVM_POLL_CONTROL, 1); +} + +void arch_haltpoll_enable(unsigned int cpu) +{ + if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL)) { + pr_err_once("host does not support poll control\n"); + pr_err_once("host upgrade recommended\n"); + return; + } + + /* Enable guest halt poll disables host halt poll */ + smp_call_function_single(cpu, kvm_disable_host_haltpoll, NULL, 1); +} +EXPORT_SYMBOL_GPL(arch_haltpoll_enable); + +void arch_haltpoll_disable(unsigned int cpu) +{ + if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL)) + return; + + /* Disable guest halt poll enables host halt poll */ + smp_call_function_single(cpu, kvm_enable_host_haltpoll, NULL, 1); +} +EXPORT_SYMBOL_GPL(arch_haltpoll_disable); +#endif |