linux-kernel - RE: [PATCH v5 16/21] kvm: x86: Add CPUID support for Intel AMX

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Message-ID: <BN9PR11MB527646BB14CE77A8FE1A639B8C4C9@BN9PR11MB5276.namprd11.prod.outlook.com>
Date:   Thu, 6 Jan 2022 00:52:55 +0000
From:   "Tian, Kevin" <kevin.tian@...el.com>
To:     "Christopherson,, Sean" <seanjc@...gle.com>,
        "Zhong, Yang" <yang.zhong@...el.com>
CC:     "x86@...nel.org" <x86@...nel.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
        "linux-kselftest@...r.kernel.org" <linux-kselftest@...r.kernel.org>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "bp@...en8.de" <bp@...en8.de>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
        "pbonzini@...hat.com" <pbonzini@...hat.com>,
        "corbet@....net" <corbet@....net>,
        "shuah@...nel.org" <shuah@...nel.org>,
        "Nakajima, Jun" <jun.nakajima@...el.com>,
        "jing2.liu@...ux.intel.com" <jing2.liu@...ux.intel.com>,
        "Liu, Jing2" <jing2.liu@...el.com>,
        "Zeng, Guang" <guang.zeng@...el.com>,
        "Wang, Wei W" <wei.w.wang@...el.com>
Subject: RE: [PATCH v5 16/21] kvm: x86: Add CPUID support for Intel AMX

> From: Sean Christopherson <seanjc@...gle.com>
> Sent: Thursday, January 6, 2022 6:29 AM
> 
> On Wed, Jan 05, 2022, Yang Zhong wrote:
> > From: Jing Liu <jing2.liu@...el.com>
> >
> > Extend CPUID emulation to support XFD, AMX_TILE, AMX_INT8 and
> > AMX_BF16. Adding those bits into kvm_cpu_caps finally activates all
> > previous logics in this series.
> >
> > Hide XFD on 32bit host kernels. Otherwise it leads to a weird situation
> > where KVM tells userspace to migrate MSR_IA32_XFD and then rejects
> > attempts to read/write the MSR.
> >
> > Signed-off-by: Jing Liu <jing2.liu@...el.com>
> > Signed-off-by: Sean Christopherson <seanjc@...gle.com>
> 
> No need for my SoB, I provided a very tiny snippet of code review.
> 

It's not tiny if compared to the rest of the patch, but we certainly can
remove it. anyway thanks for all your suggestions which are all good. 😊