kvm: svm: move WARN_ON in svm_adjust_tsc_offset (d913b904) · Commits · 戴 / test

When running the tsc_adjust kvm-unit-test on an AMD processor with the IA32_TSC_ADJUST feature enabled, the WARN_ON in svm_adjust_tsc_offset can be triggered. This WARN_ON checks for a negative adjustment in case __scale_tsc is called; however it may trigger unnecessary warnings. This patch moves the WARN_ON to trigger only if __scale_tsc will actually be called from svm_adjust_tsc_offset. In addition make adj in kvm_set_msr_common s64 since this can have signed values. Signed-off-by:

Chris J Arges <chris.j.arges@canonical.com> Signed-off-by:

Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/svm.c

+5 −3

Original line number	Diff line number	Diff line
		@@ -1056,9 +1056,11 @@ static void svm_adjust_tsc_offset(struct kvm_vcpu *vcpu, s64 adjustment, bool ho
		{
		struct vcpu_svm *svm = to_svm(vcpu);

		if (host) {
		if (svm->tsc_ratio != TSC_RATIO_DEFAULT)
		WARN_ON(adjustment < 0);
		if (host)
		adjustment = svm_scale_tsc(vcpu, adjustment);
		adjustment = svm_scale_tsc(vcpu, (u64)adjustment);
		}

		svm->vmcb->control.tsc_offset += adjustment;
		if (is_guest_mode(vcpu))

arch/x86/kvm/x86.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -2143,7 +2143,7 @@ int kvm_set_msr_common(struct kvm_vcpu vcpu, struct msr_data msr_info)
		case MSR_IA32_TSC_ADJUST:
		if (guest_cpuid_has_tsc_adjust(vcpu)) {
		if (!msr_info->host_initiated) {
		u64 adj = data - vcpu->arch.ia32_tsc_adjust_msr;
		s64 adj = data - vcpu->arch.ia32_tsc_adjust_msr;
		kvm_x86_ops->adjust_tsc_offset(vcpu, adj, true);
		}
		vcpu->arch.ia32_tsc_adjust_msr = data;

Admin message