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[11/12] KVM: VMX: Use a scaled host TSC for guest readings of MSR_IA32_TSC

Message ID 1443418691-24050-12-git-send-email-haozhong.zhang@intel.com (mailing list archive)
State New, archived
Headers show

Commit Message

Haozhong Zhang Sept. 28, 2015, 5:38 a.m. UTC 
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 <haozhong.zhang@intel.com>
---
 arch/x86/kvm/vmx.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)
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Patch

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index e282eb8..d0a2928 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2245,15 +2245,15 @@  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
  */
-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;
 }
 
 /*
@@ -2636,7 +2636,7 @@  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);