Joerg Roedel <[email protected]> writes: > On Thu, Oct 01, 2015 at 06:31:27PM -0400, Bandan Das wrote: >> >> @@ -514,7 +514,7 @@ static void skip_emulated_instruction(struct kvm_vcpu >> >> *vcpu) >> >> struct vcpu_svm *svm = to_svm(vcpu); >> >> >> >> if (svm->vmcb->control.next_rip != 0) { >> >> - WARN_ON(!static_cpu_has(X86_FEATURE_NRIPS)); >> >> + WARN_ON_ONCE(!static_cpu_has(X86_FEATURE_NRIPS)); >> >> svm->next_rip = svm->vmcb->control.next_rip; >> >> } > > I looked again how this could possibly be triggered, and I am somewhat > confused now. > > So svm->vmcb->control.next_rip is only written by hardware or in > svm_check_intercept(). Both cases write only to this field, if the > hardware supports X86_FEATURE_NRIPS. The write in nested_svm_vmexit only
Not until commit f104765b4f81fd74d69e0eb161e89096deade2db. So, an older L1 kernel will trigger it. > targets the guests VMCB, and we don't use that one again. > > So I can't see how the WARN_ON above could be triggered. Do I miss > something or might this also be a miscompilation of static_cpu_has? > > > Joerg -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
