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From: Sean Christopherson <seanjc@google.com>
To: Borislav Petkov <bp@alien8.de>
Cc: Babu Moger <babu.moger@amd.com>,
	pbonzini@redhat.com, tglx@linutronix.de, mingo@redhat.com,
	fenghua.yu@intel.com, tony.luck@intel.com, wanpengli@tencent.com,
	kvm@vger.kernel.org, thomas.lendacky@amd.com,
	peterz@infradead.org, joro@8bytes.org, x86@kernel.org,
	kyung.min.park@intel.com, linux-kernel@vger.kernel.org,
	krish.sadhukhan@oracle.com, hpa@zytor.com,
	mgross@linux.intel.com, vkuznets@redhat.com,
	kim.phillips@amd.com, wei.huang2@amd.com, jmattson@google.com
Subject: Re: [PATCH v2 2/2] KVM: SVM: Add support for Virtual SPEC_CTRL
Date: Wed, 30 Dec 2020 08:08:07 -0800	[thread overview]
Message-ID: <X+yl57S8vuU2pRil@google.com> (raw)
In-Reply-To: <20201230071501.GB22022@zn.tnic>

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().

  reply	other threads:[~2020-12-30 16:09 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-22 22:31 [PATCH v2 0/2] x86: Add the feature Virtual SPEC_CTRL Babu Moger
2020-12-22 22:31 ` [PATCH v2 1/2] x86/cpufeatures: Add the Virtual SPEC_CTRL feature Babu Moger
2020-12-30  7:15   ` Borislav Petkov
2020-12-22 22:31 ` [PATCH v2 2/2] KVM: SVM: Add support for Virtual SPEC_CTRL Babu Moger
2020-12-30  7:15   ` Borislav Petkov
2020-12-30 16:08     ` Sean Christopherson [this message]
2021-01-04 18:37       ` Babu Moger
2021-01-04 15:47   ` Tom Lendacky
2021-01-04 18:35     ` Babu Moger

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