| Message ID | 1438917872-23908-1-git-send-email-haozhong.zhang@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 07/08/2015 05:24, Haozhong Zhang wrote: > When kvm_set_msr_common() handles a guest's write to > MSR_IA32_TSC_ADJUST, it will calcuate an adjustment based on the data > written by guest and then use it to adjust TSC offset by calling a > call-back adjust_tsc_offset(). The 3rd parameter of adjust_tsc_offset() > indicates whether the adjustment is in host TSC cycles or in guest TSC > cycles. If SVM TSC scaling is enabled, adjust_tsc_offset() > [i.e. svm_adjust_tsc_offset()] will first scale the adjustment; > otherwise, it will just use the unscaled one. As the MSR write here > comes from the guest, the adjustment is in guest TSC cycles. However, > the current kvm_set_msr_common() uses it as a value in host TSC > cycles (by using true as the 3rd parameter of adjust_tsc_offset()), > which can result in an incorrect adjustment of TSC offset if SVM TSC > scaling is enabled. This patch fixes this problem. > > Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com> > --- > arch/x86/kvm/x86.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 5ef2560..3cd6cd2 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -2105,7 +2105,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) > if (guest_cpuid_has_tsc_adjust(vcpu)) { > if (!msr_info->host_initiated) { > s64 adj = data - vcpu->arch.ia32_tsc_adjust_msr; > - kvm_x86_ops->adjust_tsc_offset(vcpu, adj, true); > + adjust_tsc_offset_guest(vcpu, adj); > } > vcpu->arch.ia32_tsc_adjust_msr = data; > } > -- > 1.7.9.5 > > -- > To unsubscribe from this list: send the line "unsubscribe kvm" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Thanks, applied! Paolo -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 5ef2560..3cd6cd2 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2105,7 +2105,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) if (guest_cpuid_has_tsc_adjust(vcpu)) { if (!msr_info->host_initiated) { s64 adj = data - vcpu->arch.ia32_tsc_adjust_msr; - kvm_x86_ops->adjust_tsc_offset(vcpu, adj, true); + adjust_tsc_offset_guest(vcpu, adj); } vcpu->arch.ia32_tsc_adjust_msr = data; }
When kvm_set_msr_common() handles a guest's write to MSR_IA32_TSC_ADJUST, it will calcuate an adjustment based on the data written by guest and then use it to adjust TSC offset by calling a call-back adjust_tsc_offset(). The 3rd parameter of adjust_tsc_offset() indicates whether the adjustment is in host TSC cycles or in guest TSC cycles. If SVM TSC scaling is enabled, adjust_tsc_offset() [i.e. svm_adjust_tsc_offset()] will first scale the adjustment; otherwise, it will just use the unscaled one. As the MSR write here comes from the guest, the adjustment is in guest TSC cycles. However, the current kvm_set_msr_common() uses it as a value in host TSC cycles (by using true as the 3rd parameter of adjust_tsc_offset()), which can result in an incorrect adjustment of TSC offset if SVM TSC scaling is enabled. This patch fixes this problem. Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com> --- arch/x86/kvm/x86.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html