From: Borislav Petkov <bp@alien8.de>
To: Jiaxi Chen <jiaxi.chen@linux.intel.com>
Cc: kvm@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com,
dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com,
pbonzini@redhat.com, ndesaulniers@google.com,
alexandre.belloni@bootlin.com, peterz@infradead.org,
jpoimboe@kernel.org, chang.seok.bae@intel.com,
pawan.kumar.gupta@linux.intel.com, babu.moger@amd.com,
jmattson@google.com, sandipan.das@amd.com, tony.luck@intel.com,
sathyanarayanan.kuppuswamy@linux.intel.com, fenghua.yu@intel.com,
keescook@chromium.org, jane.malalane@citrix.com,
nathan@kernel.org, linux-kernel@vger.kernel.org,
Sean Christopherson <seanjc@google.com>
Subject: Re: [PATCH 1/6] x86: KVM: Enable CMPccXADD CPUID and expose it to guest
Date: Wed, 26 Oct 2022 19:15:06 +0200 [thread overview]
Message-ID: <Y1lrGgyIcgweVGup@zn.tnic> (raw)
In-Reply-To: <cce514da-32b4-3b84-cfad-67a05705bc9f@linux.intel.com>
On Wed, Oct 26, 2022 at 11:40:31AM +0800, Jiaxi Chen wrote:
> > What do you think about moving CPUID_7_1_EAX to be a KVM-only leaf too? AFAICT,
> > KVM passthrough is the only reason the existing features are defined.
Yap, looking at the patches which added those 2 feature flags upstream,
they don't look like some particular use was the goal but rather to
expose it to guests. Besides, AVX512 apps do their own CPUID detection.
> Since CPUID_7_1_EAX has only 5 features now, it is a big waste,
> should we move it to KVM-only leaf as Sean suggested. What's your
> opinion about this?
Yes, pls do.
And when you do, make sure to undo what
b302e4b176d0 ("x86/cpufeatures: Enumerate the new AVX512 BFLOAT16 instructions")
added.
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2022-10-26 17:15 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-19 8:47 [PATCH 0/6] x86: KVM: Expose CPUID to guest for new Intel platform instructions Jiaxi Chen
2022-10-19 8:47 ` [PATCH 1/6] x86: KVM: Enable CMPccXADD CPUID and expose it to guest Jiaxi Chen
2022-10-19 15:15 ` Sean Christopherson
2022-10-20 7:27 ` Chen, Jiaxi
2022-10-26 3:40 ` Jiaxi Chen
2022-10-26 17:15 ` Borislav Petkov [this message]
2022-10-27 2:27 ` Jiaxi Chen
2022-11-01 9:07 ` Jiaxi Chen
2022-11-01 15:07 ` Sean Christopherson
2022-11-03 2:35 ` Jiaxi Chen
2022-10-19 8:47 ` [PATCH 2/6] x86: KVM: Enable AMX-FP16 " Jiaxi Chen
2022-11-02 18:14 ` Dave Hansen
2022-11-02 18:16 ` Paolo Bonzini
2022-11-02 18:21 ` Dave Hansen
2022-11-03 2:38 ` Jiaxi Chen
2022-10-19 8:47 ` [PATCH 3/6] x86: KVM: Enable AVX-IFMA " Jiaxi Chen
2022-10-19 8:47 ` [PATCH 4/6] x86: KVM: Enable AVX-VNNI-INT8 " Jiaxi Chen
2022-10-19 8:52 ` Borislav Petkov
2022-10-19 14:57 ` Sean Christopherson
2022-10-19 15:09 ` Sean Christopherson
2022-10-26 3:33 ` Jiaxi Chen
2022-10-20 7:13 ` Chen, Jiaxi
2022-10-19 8:47 ` [PATCH 5/6] x86: KVM: Enable AVX-NE-CONVERT " Jiaxi Chen
2022-10-19 8:47 ` [PATCH 6/6] x86: KVM: Enable PREFETCHIT0/1 " Jiaxi Chen
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