---

yaml
---
r: 215912
b: refs/heads/master
c: c285545
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 34c238a1d1832d7b1f655641f52782e86396b30a
+refs/heads/master: c285545f813d7b0ce989fd34e42ad1fe785dc65d

trunk/arch/x86/include/asm/kvm_host.h

@@ -384,6 +384,9 @@ struct kvm_vcpu_arch {
 	u64 last_host_tsc;
 	u64 last_guest_tsc;
 	u64 last_kernel_ns;
+	u64 last_tsc_nsec;
+	u64 last_tsc_write;
+	bool tsc_catchup;
 
 	bool nmi_pending;
 	bool nmi_injected;
@@ -444,6 +447,9 @@ struct kvm_arch {
 	u64 last_tsc_nsec;
 	u64 last_tsc_offset;
 	u64 last_tsc_write;
+	u32 virtual_tsc_khz;
+	u32 virtual_tsc_mult;
+	s8 virtual_tsc_shift;
 
 	struct kvm_xen_hvm_config xen_hvm_config;
 

trunk/arch/x86/kvm/x86.c

@@ -962,6 +962,7 @@ static inline u64 get_kernel_ns(void)
 }
 
 static DEFINE_PER_CPU(unsigned long, cpu_tsc_khz);
+unsigned long max_tsc_khz;
 
 static inline int kvm_tsc_changes_freq(void)
 {
@@ -985,6 +986,24 @@ static inline u64 nsec_to_cycles(u64 nsec)
 	return ret;
 }
 
+static void kvm_arch_set_tsc_khz(struct kvm *kvm, u32 this_tsc_khz)
+{
+	/* Compute a scale to convert nanoseconds in TSC cycles */
+	kvm_get_time_scale(this_tsc_khz, NSEC_PER_SEC / 1000,
+			   &kvm->arch.virtual_tsc_shift,
+			   &kvm->arch.virtual_tsc_mult);
+	kvm->arch.virtual_tsc_khz = this_tsc_khz;
+}
+
+static u64 compute_guest_tsc(struct kvm_vcpu *vcpu, s64 kernel_ns)
+{
+	u64 tsc = pvclock_scale_delta(kernel_ns-vcpu->arch.last_tsc_nsec,
+				      vcpu->kvm->arch.virtual_tsc_mult,
+				      vcpu->kvm->arch.virtual_tsc_shift);
+	tsc += vcpu->arch.last_tsc_write;
+	return tsc;
+}
+
 void kvm_write_tsc(struct kvm_vcpu *vcpu, u64 data)
 {
 	struct kvm *kvm = vcpu->kvm;
@@ -1029,6 +1048,8 @@ void kvm_write_tsc(struct kvm_vcpu *vcpu, u64 data)
 
 	/* Reset of TSC must disable overshoot protection below */
 	vcpu->arch.hv_clock.tsc_timestamp = 0;
+	vcpu->arch.last_tsc_write = data;
+	vcpu->arch.last_tsc_nsec = ns;
 }
 EXPORT_SYMBOL_GPL(kvm_write_tsc);
 
@@ -1041,21 +1062,41 @@ static int kvm_guest_time_update(struct kvm_vcpu *v)
 	s64 kernel_ns, max_kernel_ns;
 	u64 tsc_timestamp;
 
-	if ((!vcpu->time_page))
-		return 0;
-
 	/* Keep irq disabled to prevent changes to the clock */
 	local_irq_save(flags);
 	kvm_get_msr(v, MSR_IA32_TSC, &tsc_timestamp);
 	kernel_ns = get_kernel_ns();
 	this_tsc_khz = __get_cpu_var(cpu_tsc_khz);
-	local_irq_restore(flags);
 
 	if (unlikely(this_tsc_khz == 0)) {
+		local_irq_restore(flags);
 		kvm_make_request(KVM_REQ_CLOCK_UPDATE, v);
 		return 1;
 	}
 
+	/*
+	 * We may have to catch up the TSC to match elapsed wall clock
+	 * time for two reasons, even if kvmclock is used.
+	 *   1) CPU could have been running below the maximum TSC rate
+	 *   2) Broken TSC compensation resets the base at each VCPU
+	 *      entry to avoid unknown leaps of TSC even when running
+	 *      again on the same CPU.  This may cause apparent elapsed
+	 *      time to disappear, and the guest to stand still or run
+	 *	very slowly.
+	 */
+	if (vcpu->tsc_catchup) {
+		u64 tsc = compute_guest_tsc(v, kernel_ns);
+		if (tsc > tsc_timestamp) {
+			kvm_x86_ops->adjust_tsc_offset(v, tsc - tsc_timestamp);
+			tsc_timestamp = tsc;
+		}
+	}
+
+	local_irq_restore(flags);
+
+	if (!vcpu->time_page)
+		return 0;
+
 	/*
 	 * Time as measured by the TSC may go backwards when resetting the base
 	 * tsc_timestamp.  The reason for this is that the TSC resolution is
@@ -1122,16 +1163,6 @@ static int kvm_guest_time_update(struct kvm_vcpu *v)
 	return 0;
 }
 
-static int kvm_request_guest_time_update(struct kvm_vcpu *v)
-{
-	struct kvm_vcpu_arch *vcpu = &v->arch;
-
-	if (!vcpu->time_page)
-		return 0;
-	kvm_make_request(KVM_REQ_CLOCK_UPDATE, v);
-	return 1;
-}
-
 static bool msr_mtrr_valid(unsigned msr)
 {
 	switch (msr) {
@@ -1455,6 +1486,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
 		}
 
 		vcpu->arch.time = data;
+		kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu);
 
 		/* we verify if the enable bit is set... */
 		if (!(data & 1))
@@ -1470,8 +1502,6 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
 			kvm_release_page_clean(vcpu->arch.time_page);
 			vcpu->arch.time_page = NULL;
 		}
-
-		kvm_request_guest_time_update(vcpu);
 		break;
 	}
 	case MSR_IA32_MCG_CTL:
@@ -2028,9 +2058,13 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 				native_read_tsc() - vcpu->arch.last_host_tsc;
 		if (tsc_delta < 0)
 			mark_tsc_unstable("KVM discovered backwards TSC");
-		if (check_tsc_unstable())
+		if (check_tsc_unstable()) {
 			kvm_x86_ops->adjust_tsc_offset(vcpu, -tsc_delta);
-		kvm_migrate_timers(vcpu);
+			vcpu->arch.tsc_catchup = 1;
+			kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu);
+		}
+		if (vcpu->cpu != cpu)
+			kvm_migrate_timers(vcpu);
 		vcpu->cpu = cpu;
 	}
 }
@@ -4461,8 +4495,7 @@ static int kvmclock_cpufreq_notifier(struct notifier_block *nb, unsigned long va
 		kvm_for_each_vcpu(i, vcpu, kvm) {
 			if (vcpu->cpu != freq->cpu)
 				continue;
-			if (!kvm_request_guest_time_update(vcpu))
-				continue;
+			kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu);
 			if (vcpu->cpu != smp_processor_id())
 				send_ipi = 1;
 		}
@@ -4517,11 +4550,20 @@ static void kvm_timer_init(void)
 {
 	int cpu;
 
+	max_tsc_khz = tsc_khz;
 	register_hotcpu_notifier(&kvmclock_cpu_notifier_block);
 	if (!boot_cpu_has(X86_FEATURE_CONSTANT_TSC)) {
+#ifdef CONFIG_CPU_FREQ
+		struct cpufreq_policy policy;
+		memset(&policy, 0, sizeof(policy));
+		cpufreq_get_policy(&policy, get_cpu());
+		if (policy.cpuinfo.max_freq)
+			max_tsc_khz = policy.cpuinfo.max_freq;
+#endif
 		cpufreq_register_notifier(&kvmclock_cpufreq_notifier_block,
 					  CPUFREQ_TRANSITION_NOTIFIER);
 	}
+	pr_debug("kvm: max_tsc_khz = %ld\n", max_tsc_khz);
 	for_each_online_cpu(cpu)
 		smp_call_function_single(cpu, tsc_khz_changed, NULL, 1);
 }
@@ -5752,7 +5794,7 @@ int kvm_arch_hardware_enable(void *garbage)
 	list_for_each_entry(kvm, &vm_list, vm_list)
 		kvm_for_each_vcpu(i, vcpu, kvm)
 			if (vcpu->cpu == smp_processor_id())
-				kvm_request_guest_time_update(vcpu);
+				kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu);
 	return kvm_x86_ops->hardware_enable(garbage);
 }
 
@@ -5803,6 +5845,9 @@ int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
 	}
 	vcpu->arch.pio_data = page_address(page);
 
+	if (!kvm->arch.virtual_tsc_khz)
+		kvm_arch_set_tsc_khz(kvm, max_tsc_khz);
+
 	r = kvm_mmu_create(vcpu);
 	if (r < 0)
 		goto fail_free_pio_data;