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Commit d913b904 authored by Chris J Arges's avatar Chris J Arges Committed by Paolo Bonzini
Browse files

kvm: svm: move WARN_ON in svm_adjust_tsc_offset 



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: default avatarChris J Arges <chris.j.arges@canonical.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 54b98bff

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;