linux-kernel - [PATCH v2 02/12] KVM: x86: Add a common TSC scaling ratio field in kvm_vcpu

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Date:	Tue, 20 Oct 2015 15:39:02 +0800
From:	Haozhong Zhang <haozhong.zhang@...el.com>
To:	kvm@...r.kernel.org
Cc:	Gleb Natapov <gleb@...nel.org>,
	Paolo Bonzini <pbonzini@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	Joerg Roedel <joro@...tes.org>,
	Wanpeng Li <wanpeng.li@...mail.com>,
	Xiao Guangrong <guangrong.xiao@...ux.intel.com>,
	mdontu@...defender.com, Kai Huang <kai.huang@...ux.intel.com>,
	Andy Lutomirski <luto@...nel.org>,
	linux-kernel@...r.kernel.org,
	Haozhong Zhang <haozhong.zhang@...el.com>
Subject: [PATCH v2 02/12] 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@...el.com>
---
 arch/x86/include/asm/kvm_host.h |  1 +
 arch/x86/kvm/svm.c              | 23 +++++++++--------------
 arch/x86/kvm/x86.c              |  5 ++++-
 3 files changed, 14 insertions(+), 15 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 0540dc8..1e08ad5 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/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 */
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 55f5f49..04b58cf 100644
--- a/arch/x86/kvm/svm.c
+++ b/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;
 };
@@ -992,24 +990,22 @@ 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;
 	}
 
@@ -1034,7 +1030,7 @@ 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)
@@ -1068,7 +1064,7 @@ 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);
 	}
@@ -1240,8 +1236,6 @@ 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;
@@ -1311,6 +1305,7 @@ static void svm_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);
 	int i;
+	u64 tsc_ratio = vcpu->arch.tsc_scaling_ratio;
 
 	if (unlikely(cpu != vcpu->cpu)) {
 		svm->asid_generation = 0;
@@ -1328,9 +1323,9 @@ static void svm_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 		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);
+	    tsc_ratio != __this_cpu_read(current_tsc_ratio)) {
+		__this_cpu_write(current_tsc_ratio, tsc_ratio);
+		wrmsrl(MSR_AMD64_TSC_RATIO, tsc_ratio);
 	}
 }
 
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 79cbbb5..8849e8b 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1258,8 +1258,11 @@ 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,
-- 
2.4.8

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