> -----Original Message-----
> From: Sean Christopherson <sea...@google.com>
> Sent: Wednesday, December 30, 2020 10:08 AM
> To: Borislav Petkov <b...@alien8.de>
> Cc: Moger, Babu <babu.mo...@amd.com>; pbonz...@redhat.com;
> t...@linutronix.de; mi...@redhat.com; fenghua...@intel.com;
> tony.l...@intel.com; wanpen...@tencent.com; k...@vger.kernel.org;
> Lendacky, Thomas <thomas.lenda...@amd.com>; pet...@infradead.org;
> j...@8bytes.org; x...@kernel.org; kyung.min.p...@intel.com; linux-
> ker...@vger.kernel.org; krish.sadhuk...@oracle.com; h...@zytor.com;
> mgr...@linux.intel.com; vkuzn...@redhat.com; Phillips, Kim
> <kim.phill...@amd.com>; Huang2, Wei <wei.hua...@amd.com>;
> jmatt...@google.com
> Subject: Re: [PATCH v2 2/2] KVM: SVM: Add support for Virtual SPEC_CTRL
>
> On Wed, Dec 30, 2020, Borislav Petkov wrote:
> > On Tue, Dec 22, 2020 at 04:31:55PM -0600, Babu Moger wrote:
> > > @@ -2549,7 +2559,10 @@ static int svm_get_msr(struct kvm_vcpu *vcpu,
> struct msr_data *msr_info)
> > > !guest_cpuid_has(vcpu, X86_FEATURE_AMD_SSBD))
> > > return 1;
> > >
> > > - msr_info->data = svm->spec_ctrl;
> > > + if (static_cpu_has(X86_FEATURE_V_SPEC_CTRL))
> > > + msr_info->data = svm->vmcb->save.spec_ctrl;
> > > + else
> > > + msr_info->data = svm->spec_ctrl;
> > > break;
> > > case MSR_AMD64_VIRT_SPEC_CTRL:
> > > if (!msr_info->host_initiated &&
> > > @@ -2640,6 +2653,8 @@ static int svm_set_msr(struct kvm_vcpu *vcpu,
> struct msr_data *msr)
> > > return 1;
> > >
> > > svm->spec_ctrl = data;
> > > + if (static_cpu_has(X86_FEATURE_V_SPEC_CTRL))
> > > + svm->vmcb->save.spec_ctrl = data;
> > > if (!data)
> > > break;
> > >
> >
> > Are the get/set_msr() accessors such a fast path that they need
> > static_cpu_has() ?
>
> Nope, they can definitely use boot_cpu_has().
With Tom's latest comment, this change may not be required.
I will remove these changes.
Thanks
Babu
