From d7add05458084a5e3d65925764a02ca9c8202c1e Mon Sep 17 00:00:00 2001 From: Haozhong Zhang Date: Fri, 7 Aug 2015 11:24:32 +0800 Subject: [PATCH] KVM: x86: Use adjustment in guest cycles when handling MSR_IA32_TSC_ADJUST 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 Cc: stable@vger.linux.org Signed-off-by: Paolo Bonzini --- 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 c5e88a881899..8f0f6eca69da 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; } -- 2.20.1