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Commit be7b263e authored by Haozhong Zhang's avatar Haozhong Zhang Committed by Paolo Bonzini
Browse files

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: default avatarHaozhong Zhang <haozhong.zhang@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent ff2c3a18

arch/x86/kvm/vmx.c

+5 −4
Original line number Diff line number Diff line
@@ -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);