KVM: x86: Add a common TSC scaling ratio field in kvm_vcpu_arch

This patch moves the field of TSC scaling ratio from the architecture
struct vcpu_svm to the common struct kvm_vcpu_arch.
Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/include/asm/kvm_host.h

@@ -505,6 +505,7 @@ struct kvm_vcpu_arch {
 	u32 virtual_tsc_mult;
 	u32 virtual_tsc_khz;
 	s64 ia32_tsc_adjust_msr;
+	u64 tsc_scaling_ratio;
 
 	atomic_t nmi_queued;  /* unprocessed asynchronous NMIs */
 	unsigned nmi_pending; /* NMI queued after currently running handler */

arch/x86/kvm/svm.c

@@ -158,8 +158,6 @@ struct vcpu_svm {
 	unsigned long int3_rip;
 	u32 apf_reason;
 
-	u64  tsc_ratio;
-
 	/* cached guest cpuid flags for faster access */
 	bool nrips_enabled	: 1;
 };
@@ -991,24 +989,22 @@ static u64 __scale_tsc(u64 ratio, u64 tsc)
 
 static u64 svm_scale_tsc(struct kvm_vcpu *vcpu, u64 tsc)
 {
-	struct vcpu_svm *svm = to_svm(vcpu);
 	u64 _tsc = tsc;
 
-	if (svm->tsc_ratio != TSC_RATIO_DEFAULT)
-		_tsc = __scale_tsc(svm->tsc_ratio, tsc);
+	if (vcpu->arch.tsc_scaling_ratio != TSC_RATIO_DEFAULT)
+		_tsc = __scale_tsc(vcpu->arch.tsc_scaling_ratio, tsc);
 
 	return _tsc;
 }
 
 static void svm_set_tsc_khz(struct kvm_vcpu *vcpu, u32 user_tsc_khz, bool scale)
 {
-	struct vcpu_svm *svm = to_svm(vcpu);
 	u64 ratio;
 	u64 khz;
 
 	/* Guest TSC same frequency as host TSC? */
 	if (!scale) {
-		svm->tsc_ratio = TSC_RATIO_DEFAULT;
+		vcpu->arch.tsc_scaling_ratio = TSC_RATIO_DEFAULT;
 		return;
 	}
 
@@ -1033,7 +1029,7 @@ static void svm_set_tsc_khz(struct kvm_vcpu *vcpu, u32 user_tsc_khz, bool scale)
 				user_tsc_khz);
 		return;
 	}
-	svm->tsc_ratio             = ratio;
+	vcpu->arch.tsc_scaling_ratio = ratio;
 }
 
 static u64 svm_read_tsc_offset(struct kvm_vcpu *vcpu)
@@ -1067,7 +1063,7 @@ static void svm_adjust_tsc_offset(struct kvm_vcpu *vcpu, s64 adjustment, bool ho
 	struct vcpu_svm *svm = to_svm(vcpu);
 
 	if (host) {
-		if (svm->tsc_ratio != TSC_RATIO_DEFAULT)
+		if (vcpu->arch.tsc_scaling_ratio != TSC_RATIO_DEFAULT)
 			WARN_ON(adjustment < 0);
 		adjustment = svm_scale_tsc(vcpu, (u64)adjustment);
 	}
@@ -1238,8 +1234,6 @@ static struct kvm_vcpu *svm_create_vcpu(struct kvm *kvm, unsigned int id)
 		goto out;
 	}
 
-	svm->tsc_ratio = TSC_RATIO_DEFAULT;
-
 	err = kvm_vcpu_init(&svm->vcpu, kvm, id);
 	if (err)
 		goto free_svm;
@@ -1325,10 +1319,12 @@ static void svm_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 	for (i = 0; i < NR_HOST_SAVE_USER_MSRS; i++)
 		rdmsrl(host_save_user_msrs[i], svm->host_user_msrs[i]);
 
-	if (static_cpu_has(X86_FEATURE_TSCRATEMSR) &&
-	    svm->tsc_ratio != __this_cpu_read(current_tsc_ratio)) {
-		__this_cpu_write(current_tsc_ratio, svm->tsc_ratio);
-		wrmsrl(MSR_AMD64_TSC_RATIO, svm->tsc_ratio);
+	if (static_cpu_has(X86_FEATURE_TSCRATEMSR)) {
+		u64 tsc_ratio = vcpu->arch.tsc_scaling_ratio;
+		if (tsc_ratio != __this_cpu_read(current_tsc_ratio)) {
+			__this_cpu_write(current_tsc_ratio, tsc_ratio);
+			wrmsrl(MSR_AMD64_TSC_RATIO, tsc_ratio);
+		}
 	}
 }
 

arch/x86/kvm/x86.c

@@ -113,6 +113,7 @@ u8   __read_mostly kvm_tsc_scaling_ratio_frac_bits;
 EXPORT_SYMBOL_GPL(kvm_tsc_scaling_ratio_frac_bits);
 u64  __read_mostly kvm_max_tsc_scaling_ratio;
 EXPORT_SYMBOL_GPL(kvm_max_tsc_scaling_ratio);
+static u64 __read_mostly kvm_default_tsc_scaling_ratio;
 
 /* tsc tolerance in parts per million - default to 1/2 of the NTP threshold */
 static u32 __read_mostly tsc_tolerance_ppm = 250;
@@ -1258,8 +1259,11 @@ static void kvm_set_tsc_khz(struct kvm_vcpu *vcpu, u32 this_tsc_khz)
 	int use_scaling = 0;
 
 	/* tsc_khz can be zero if TSC calibration fails */
-	if (this_tsc_khz == 0)
+	if (this_tsc_khz == 0) {
+		/* set tsc_scaling_ratio to a safe value */
+		vcpu->arch.tsc_scaling_ratio = kvm_default_tsc_scaling_ratio;
 		return;
+	}
 
 	/* Compute a scale to convert nanoseconds in TSC cycles */
 	kvm_get_time_scale(this_tsc_khz, NSEC_PER_SEC / 1000,
@@ -7367,6 +7371,9 @@ int kvm_arch_hardware_setup(void)
 	if (r != 0)
 		return r;
 
+	if (kvm_has_tsc_control)
+		kvm_default_tsc_scaling_ratio = 1ULL << kvm_tsc_scaling_ratio_frac_bits;
+
 	kvm_init_msr_list();
 	return 0;
 }