KVM: Fix kvmclock on !constant_tsc boxes (c8076604) · Commits · 戴 / test

arch/x86/kvm/x86.c

+94 −9

Original line number	Diff line number	Diff line
		@@ -36,6 +36,7 @@
		#include <linux/highmem.h>
		#include <linux/iommu.h>
		#include <linux/intel-iommu.h>
		#include <linux/cpufreq.h>

		#include <asm/uaccess.h>
		#include <asm/msr.h>
		@@ -617,6 +618,8 @@ static void kvm_set_time_scale(uint32_t tsc_khz, struct pvclock_vcpu_time_info *
		hv_clock->tsc_to_system_mul);
		}

		static DEFINE_PER_CPU(unsigned long, cpu_tsc_khz);

		static void kvm_write_guest_time(struct kvm_vcpu *v)
		{
		struct timespec ts;
		@@ -627,9 +630,9 @@ static void kvm_write_guest_time(struct kvm_vcpu *v)
		if ((!vcpu->time_page))
		return;

		if (unlikely(vcpu->hv_clock_tsc_khz != tsc_khz)) {
		kvm_set_time_scale(tsc_khz, &vcpu->hv_clock);
		vcpu->hv_clock_tsc_khz = tsc_khz;
		if (unlikely(vcpu->hv_clock_tsc_khz != __get_cpu_var(cpu_tsc_khz))) {
		kvm_set_time_scale(__get_cpu_var(cpu_tsc_khz), &vcpu->hv_clock);
		vcpu->hv_clock_tsc_khz = __get_cpu_var(cpu_tsc_khz);
		}

		/* Keep irq disabled to prevent changes to the clock */
		@@ -660,6 +663,16 @@ static void kvm_write_guest_time(struct kvm_vcpu *v)
		mark_page_dirty(v->kvm, vcpu->time >> PAGE_SHIFT);
		}

		static int kvm_request_guest_time_update(struct kvm_vcpu *v)
		{
		struct kvm_vcpu_arch *vcpu = &v->arch;

		if (!vcpu->time_page)
		return 0;
		set_bit(KVM_REQ_KVMCLOCK_UPDATE, &v->requests);
		return 1;
		}

		static bool msr_mtrr_valid(unsigned msr)
		{
		switch (msr) {
		@@ -790,7 +803,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
		vcpu->arch.time_page = NULL;
		}

		kvm_write_guest_time(vcpu);
		kvm_request_guest_time_update(vcpu);
		break;
		}
		default:
		@@ -1000,6 +1013,7 @@ int kvm_dev_ioctl_check_extension(long ext)
		case KVM_CAP_MMU_SHADOW_CACHE_CONTROL:
		case KVM_CAP_SET_TSS_ADDR:
		case KVM_CAP_EXT_CPUID:
		case KVM_CAP_CLOCKSOURCE:
		case KVM_CAP_PIT:
		case KVM_CAP_NOP_IO_DELAY:
		case KVM_CAP_MP_STATE:
		@@ -1025,9 +1039,6 @@ int kvm_dev_ioctl_check_extension(long ext)
		case KVM_CAP_IOMMU:
		r = iommu_found();
		break;
		case KVM_CAP_CLOCKSOURCE:
		r = boot_cpu_has(X86_FEATURE_CONSTANT_TSC);
		break;
		default:
		r = 0;
		break;
		@@ -1098,7 +1109,7 @@ out:
		void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
		{
		kvm_x86_ops->vcpu_load(vcpu, cpu);
		kvm_write_guest_time(vcpu);
		kvm_request_guest_time_update(vcpu);
		}

		void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
		@@ -2642,9 +2653,72 @@ int kvm_emulate_pio_string(struct kvm_vcpu vcpu, struct kvm_run run, int in,
		}
		EXPORT_SYMBOL_GPL(kvm_emulate_pio_string);

		static void bounce_off(void *info)
		{
		/* nothing */
		}

		static unsigned int ref_freq;
		static unsigned long tsc_khz_ref;

		static int kvmclock_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
		void *data)
		{
		struct cpufreq_freqs *freq = data;
		struct kvm *kvm;
		struct kvm_vcpu *vcpu;
		int i, send_ipi = 0;

		if (!ref_freq)
		ref_freq = freq->old;

		if (val == CPUFREQ_PRECHANGE && freq->old > freq->new)
		return 0;
		if (val == CPUFREQ_POSTCHANGE && freq->old < freq->new)
		return 0;
		per_cpu(cpu_tsc_khz, freq->cpu) = cpufreq_scale(tsc_khz_ref, ref_freq, freq->new);

		spin_lock(&kvm_lock);
		list_for_each_entry(kvm, &vm_list, vm_list) {
		for (i = 0; i < KVM_MAX_VCPUS; ++i) {
		vcpu = kvm->vcpus[i];
		if (!vcpu)
		continue;
		if (vcpu->cpu != freq->cpu)
		continue;
		if (!kvm_request_guest_time_update(vcpu))
		continue;
		if (vcpu->cpu != smp_processor_id())
		send_ipi++;
		}
		}
		spin_unlock(&kvm_lock);

		if (freq->old < freq->new && send_ipi) {
		/*
		* We upscale the frequency. Must make the guest
		* doesn't see old kvmclock values while running with
		* the new frequency, otherwise we risk the guest sees
		* time go backwards.
		*
		* In case we update the frequency for another cpu
		* (which might be in guest context) send an interrupt
		* to kick the cpu out of guest context. Next time
		* guest context is entered kvmclock will be updated,
		* so the guest will not see stale values.
		*/
		smp_call_function_single(freq->cpu, bounce_off, NULL, 1);
		}
		return 0;
		}

		static struct notifier_block kvmclock_cpufreq_notifier_block = {
		.notifier_call = kvmclock_cpufreq_notifier
		};

		int kvm_arch_init(void *opaque)
		{
		int r;
		int r, cpu;
		struct kvm_x86_ops ops = (struct kvm_x86_ops )opaque;

		if (kvm_x86_ops) {
		@@ -2675,6 +2749,15 @@ int kvm_arch_init(void *opaque)
		kvm_mmu_set_base_ptes(PT_PRESENT_MASK);
		kvm_mmu_set_mask_ptes(PT_USER_MASK, PT_ACCESSED_MASK,
		PT_DIRTY_MASK, PT64_NX_MASK, 0, 0);

		for_each_possible_cpu(cpu)
		per_cpu(cpu_tsc_khz, cpu) = tsc_khz;
		if (!boot_cpu_has(X86_FEATURE_CONSTANT_TSC)) {
		tsc_khz_ref = tsc_khz;
		cpufreq_register_notifier(&kvmclock_cpufreq_notifier_block,
		CPUFREQ_TRANSITION_NOTIFIER);
		}

		return 0;

		out:
		@@ -3010,6 +3093,8 @@ static int vcpu_enter_guest(struct kvm_vcpu vcpu, struct kvm_run kvm_run)
		if (vcpu->requests) {
		if (test_and_clear_bit(KVM_REQ_MIGRATE_TIMER, &vcpu->requests))
		__kvm_migrate_timers(vcpu);
		if (test_and_clear_bit(KVM_REQ_KVMCLOCK_UPDATE, &vcpu->requests))
		kvm_write_guest_time(vcpu);
		if (test_and_clear_bit(KVM_REQ_MMU_SYNC, &vcpu->requests))
		kvm_mmu_sync_roots(vcpu);
		if (test_and_clear_bit(KVM_REQ_TLB_FLUSH, &vcpu->requests))

include/linux/kvm_host.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -37,6 +37,7 @@
		#define KVM_REQ_PENDING_TIMER 5
		#define KVM_REQ_UNHALT 6
		#define KVM_REQ_MMU_SYNC 7
		#define KVM_REQ_KVMCLOCK_UPDATE 8

		#define KVM_USERSPACE_IRQ_SOURCE_ID 0

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