Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1251398

[PATCH v2 11/12] KVM: VMX: Use a scaled host TSC for guest readings of MSR_IA32_TSC

Show all headers | View raw

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 | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index c241ff3..a02b59c 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2372,15 +2372,16 @@ 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;
 }
 
 /*
@@ -2772,7 +2773,7 @@ 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);
-- 
2.4.8

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH v2 00/12] KVM: x86: add support for VMX TSC scaling Haozhong Zhang <haozhong.zhang@intel.com> - 2015-10-20 09:50 +0200
  [PATCH v2 09/12] KVM: VMX: Enable and initialize VMX TSC scaling Haozhong Zhang <haozhong.zhang@intel.com> - 2015-10-20 09:50 +0200
  [PATCH v2 03/12] KVM: x86: Add a common TSC scaling function Haozhong Zhang <haozhong.zhang@intel.com> - 2015-10-20 09:50 +0200
  [PATCH v2 02/12] KVM: x86: Add a common TSC scaling ratio field in kvm_vcpu_arch Haozhong Zhang <haozhong.zhang@intel.com> - 2015-10-20 09:50 +0200
  [PATCH v2 12/12] KVM: VMX: Dump TSC multiplier in dump_vmcs() Haozhong Zhang <haozhong.zhang@intel.com> - 2015-10-20 09:50 +0200
  [PATCH v2 06/12] KVM: x86: Move TSC scaling logic out of call-back adjust_tsc_offset() Haozhong Zhang <haozhong.zhang@intel.com> - 2015-10-20 09:50 +0200
  [PATCH v2 11/12] KVM: VMX: Use a scaled host TSC for guest readings of MSR_IA32_TSC Haozhong Zhang <haozhong.zhang@intel.com> - 2015-10-20 10:00 +0200
  [PATCH v2 01/12] KVM: x86: Collect information for setting TSC scaling ratio Haozhong Zhang <haozhong.zhang@intel.com> - 2015-10-20 10:00 +0200
  [PATCH v2 05/12] KVM: x86: Replace call-back compute_tsc_offset() with a common function Haozhong Zhang <haozhong.zhang@intel.com> - 2015-10-20 10:00 +0200
  [PATCH v2 04/12] KVM: x86: Replace call-back set_tsc_khz() with a common function Haozhong Zhang <haozhong.zhang@intel.com> - 2015-10-20 10:00 +0200
  Re: [PATCH v2 00/12] KVM: x86: add support for VMX TSC scaling Joerg Roedel <joro@8bytes.org> - 2015-10-23 12:10 +0200
    Re: [PATCH v2 00/12] KVM: x86: add support for VMX TSC scaling Haozhong Zhang <haozhong.zhang@intel.com> - 2015-10-23 14:40 +0200
      Re: [PATCH v2 00/12] KVM: x86: add support for VMX TSC scaling Joerg Roedel <joro@8bytes.org> - 2015-10-23 14:50 +0200
        Re: [PATCH v2 00/12] KVM: x86: add support for VMX TSC scaling Paolo Bonzini <pbonzini@redhat.com> - 2015-10-23 15:00 +0200
          Re: [PATCH v2 00/12] KVM: x86: add support for VMX TSC scaling Haozhong Zhang <haozhong.zhang@intel.com> - 2015-10-23 16:40 +0200
        Re: [PATCH v2 00/12] KVM: x86: add support for VMX TSC scaling Haozhong Zhang <haozhong.zhang@intel.com> - 2015-10-23 15:00 +0200
  Re: [PATCH v2 00/12] KVM: x86: add support for VMX TSC scaling Haozhong Zhang <haozhong.zhang@intel.com> - 2015-10-23 16:40 +0200

csiph-web