From be7b263ea925324e54e48c3558d4719be5374053 Mon Sep 17 00:00:00 2001 From: Haozhong Zhang Date: Tue, 20 Oct 2015 15:39:11 +0800 Subject: [PATCH] KVM: VMX: Use a scaled host TSC for guest readings of MSR_IA32_TSC This patch makes kvm-intel to return a scaled host TSC plus the TSC offset when handling guest readings to MSR_IA32_TSC. Signed-off-by: Haozhong Zhang Signed-off-by: Paolo Bonzini --- arch/x86/kvm/vmx.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 890295287afa..c6016e4a5af0 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -2371,15 +2371,16 @@ static void setup_msrs(struct vcpu_vmx *vmx) /* * reads and returns guest's timestamp counter "register" - * guest_tsc = host_tsc + tsc_offset -- 21.3 + * guest_tsc = (host_tsc * tsc multiplier) >> 48 + tsc_offset + * -- Intel TSC Scaling for Virtualization White Paper, sec 1.3 */ -static u64 guest_read_tsc(void) +static u64 guest_read_tsc(struct kvm_vcpu *vcpu) { u64 host_tsc, tsc_offset; host_tsc = rdtsc(); tsc_offset = vmcs_read64(TSC_OFFSET); - return host_tsc + tsc_offset; + return kvm_scale_tsc(vcpu, host_tsc) + tsc_offset; } /* @@ -2771,7 +2772,7 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) case MSR_EFER: return kvm_get_msr_common(vcpu, msr_info); case MSR_IA32_TSC: - msr_info->data = guest_read_tsc(); + msr_info->data = guest_read_tsc(vcpu); break; case MSR_IA32_SYSENTER_CS: msr_info->data = vmcs_read32(GUEST_SYSENTER_CS); -- 2.20.1