From: Babu Moger <babu.moger@amd.com>
To: Jim Mattson <jmattson@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"Yu, Fenghua" <fenghua.yu@intel.com>,
Tony Luck <tony.luck@intel.com>,
Wanpeng Li <wanpengli@tencent.com>,
kvm list <kvm@vger.kernel.org>,
Tom Lendacky <thomas.lendacky@amd.com>,
Peter Zijlstra <peterz@infradead.org>,
Sean Christopherson <seanjc@google.com>,
Joerg Roedel <joro@8bytes.org>,
the arch/x86 maintainers <x86@kernel.org>,
kyung.min.park@intel.com, LKML <linux-kernel@vger.kernel.org>,
Krish Sadhukhan <krish.sadhukhan@oracle.com>,
"H . Peter Anvin" <hpa@zytor.com>,
mgross@linux.intel.com, Vitaly Kuznetsov <vkuznets@redhat.com>,
kim.phillips@amd.com, wei.huang2@amd.com
Subject: Re: [PATCH 1/2] x86/cpufeatures: Add the Virtual SPEC_CTRL feature
Date: Wed, 9 Dec 2020 16:39:31 -0600 [thread overview]
Message-ID: <2e929c9a-9da9-e7da-9fd4-8e0ea2163a19@amd.com> (raw)
In-Reply-To: <CALMp9eTk6B2832EN8EhL51m8UqmHLTfeOjdKs8TvFSSAUxGk2Q@mail.gmail.com>
On 12/7/20 5:22 PM, Jim Mattson wrote:
> On Mon, Dec 7, 2020 at 2:38 PM Babu Moger <babu.moger@amd.com> wrote:
>>
>> Newer AMD processors have a feature to virtualize the use of the SPEC_CTRL
>> MSR. This feature is identified via CPUID 0x8000000A_EDX[20]. When present,
>> the SPEC_CTRL MSR is automatically virtualized and no longer requires
>> hypervisor intervention.
>>
>> Signed-off-by: Babu Moger <babu.moger@amd.com>
>> ---
>> arch/x86/include/asm/cpufeatures.h | 1 +
>> 1 file changed, 1 insertion(+)
>>
>> diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
>> index dad350d42ecf..d649ac5ed7c7 100644
>> --- a/arch/x86/include/asm/cpufeatures.h
>> +++ b/arch/x86/include/asm/cpufeatures.h
>> @@ -335,6 +335,7 @@
>> #define X86_FEATURE_AVIC (15*32+13) /* Virtual Interrupt Controller */
>> #define X86_FEATURE_V_VMSAVE_VMLOAD (15*32+15) /* Virtual VMSAVE VMLOAD */
>> #define X86_FEATURE_VGIF (15*32+16) /* Virtual GIF */
>> +#define X86_FEATURE_V_SPEC_CTRL (15*32+20) /* Virtual SPEC_CTRL */
>
> Shouldn't this bit be reported by KVM_GET_SUPPORTED_CPUID when it's
> enumerated on the host?
Jim, I am not sure if this needs to be reported by
KVM_GET_SUPPORTED_CPUID. I dont see V_VMSAVE_VMLOAD or VGIF being reported
via KVM_GET_SUPPORTED_CPUID. Do you see the need for that?
>> /* Intel-defined CPU features, CPUID level 0x00000007:0 (ECX), word 16 */
>> #define X86_FEATURE_AVX512VBMI (16*32+ 1) /* AVX512 Vector Bit Manipulation instructions*/
>>
next prev parent reply other threads:[~2020-12-09 22:41 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-07 22:37 [PATCH 0/2] x86: Add the feature Virtual SPEC_CTRL Babu Moger
2020-12-07 22:37 ` [PATCH 1/2] x86/cpufeatures: Add the Virtual SPEC_CTRL feature Babu Moger
2020-12-07 23:22 ` Jim Mattson
2020-12-09 22:39 ` Babu Moger [this message]
2020-12-09 23:11 ` Jim Mattson
2020-12-22 16:14 ` Babu Moger
2020-12-22 17:41 ` Sean Christopherson
2020-12-22 18:07 ` Babu Moger
2020-12-07 22:37 ` [PATCH 2/2] KVM: SVM: Add support for Virtual SPEC_CTRL Babu Moger
2020-12-07 23:06 ` Jim Mattson
2020-12-10 21:26 ` Babu Moger
2020-12-10 21:36 ` Jim Mattson
2020-12-10 22:57 ` Babu Moger
2020-12-22 16:14 ` Babu Moger
2020-12-07 23:13 ` Sean Christopherson
2020-12-10 21:31 ` Babu Moger
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