linux-kernel - [KVM timekeeping 23/35] Set initial TSC rate conversion factors

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Date:	Thu, 19 Aug 2010 22:07:37 -1000
From:	Zachary Amsden <zamsden@...hat.com>
To:	kvm@...r.kernel.org
Cc:	Zachary Amsden <zamsden@...hat.com>, Avi Kivity <avi@...hat.com>,
	Marcelo Tosatti <mtosatti@...hat.com>,
	Glauber Costa <glommer@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	John Stultz <johnstul@...ibm.com>, linux-kernel@...r.kernel.org
Subject: [KVM timekeeping 23/35] Set initial TSC rate conversion factors

Signed-off-by: Zachary Amsden <zamsden@...hat.com>
---
 arch/x86/include/asm/kvm_host.h |    3 +++
 arch/x86/kvm/x86.c              |   12 ++++++++++++
 2 files changed, 15 insertions(+), 0 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 638cae5..3a54cc1 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -403,6 +403,9 @@ 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;
 
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 3691e70..d715ec0 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -918,6 +918,15 @@ static inline u64 nsec_to_cycles(u64 nsec)
 	return (nsec * __get_cpu_var(cpu_tsc_khz)) / USEC_PER_SEC;
 }
 
+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;
+}
+
 void kvm_write_tsc(struct kvm_vcpu *vcpu, u64 data)
 {
 	struct kvm *kvm = vcpu->kvm;
@@ -5636,6 +5645,9 @@ 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;
-- 
1.7.1

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