February 25, 2025 at 11:47 AM, "Sean Christopherson" <seanjc@xxxxxxxxxx> wrote: > > On Wed, Feb 19, 2025, Yosry Ahmed wrote: > > > > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c > > index 6c56d5235f0f3..729a8ee24037b 100644 > > --- a/arch/x86/kvm/vmx/vmx.c > > +++ b/arch/x86/kvm/vmx/vmx.c > > @@ -1478,7 +1478,8 @@ void vmx_vcpu_load_vmcs(struct kvm_vcpu *vcpu, int cpu, > > * may switch the active VMCS multiple times). > > */ > > if (!buddy || WARN_ON_ONCE(buddy->vmcs != prev)) > > - indirect_branch_prediction_barrier(); > > + if (cpu_feature_enabled(X86_FEATURE_USE_IBPB)) > > Combine this into a single if-statement, to make it readable and because as-is > the outer if would need curly braces. > And since this check will stay around in the form of a static_branch, I vote to > check it first so that the checks on "buddy" are elided if vcpu_load_ibpb is disabled. > That'll mean the WARN_ON_ONCE() won't fire if we have a bug and someone is running > with mitigations disabled, but I'm a-ok with that. SGTM, will do that in the next version. Thanks!
