Messages in this thread | | | Date | Mon, 27 Mar 2023 11:46:25 +0800 | Subject | Re: [PATCH 2/6] KVM: VMX: Passthrough MSR_IA32_PRED_CMD based purely on host+guest CPUID | From | Xiaoyao Li <> |
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On 3/22/2023 9:14 AM, Sean Christopherson wrote: > Passthrough MSR_IA32_PRED_CMD based purely on whether or not the MSR is > supported and enabled, i.e. don't wait until the first write. There's no > benefit to deferred passthrough, and the extra logic only adds complexity.
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
> Signed-off-by: Sean Christopherson <seanjc@google.com> > --- > arch/x86/kvm/vmx/vmx.c | 16 +++------------- > 1 file changed, 3 insertions(+), 13 deletions(-) > > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c > index f777509ecf17..5c01c76c0d45 100644 > --- a/arch/x86/kvm/vmx/vmx.c > +++ b/arch/x86/kvm/vmx/vmx.c > @@ -2298,19 +2298,6 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) > break; > > wrmsrl(MSR_IA32_PRED_CMD, PRED_CMD_IBPB); > - > - /* > - * For non-nested: > - * When it's written (to non-zero) for the first time, pass > - * it through. > - * > - * For nested: > - * The handling of the MSR bitmap for L2 guests is done in > - * nested_vmx_prepare_msr_bitmap. We should not touch the > - * vmcs02.msr_bitmap here since it gets completely overwritten > - * in the merging. > - */ > - vmx_disable_intercept_for_msr(vcpu, MSR_IA32_PRED_CMD, MSR_TYPE_W); > break; > case MSR_IA32_CR_PAT: > if (!kvm_pat_valid(data)) > @@ -7743,6 +7730,9 @@ static void vmx_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu) > vmx_set_intercept_for_msr(vcpu, MSR_IA32_XFD_ERR, MSR_TYPE_R, > !guest_cpuid_has(vcpu, X86_FEATURE_XFD)); > > + if (boot_cpu_has(X86_FEATURE_IBPB)) > + vmx_set_intercept_for_msr(vcpu, MSR_IA32_PRED_CMD, MSR_TYPE_W, > + !guest_has_pred_cmd_msr(vcpu)); > > set_cr4_guest_host_mask(vmx); >
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