linux-kernel - RE: Thoughts of AMX KVM support based on latest kernel

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Message-ID: <87tugb3r7w.ffs@tglx>
Date:   Wed, 17 Nov 2021 13:24:19 +0100
From:   Thomas Gleixner <tglx@...utronix.de>
To:     "Tian, Kevin" <kevin.tian@...el.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        "Nakajima, Jun" <jun.nakajima@...el.com>
Cc:     "Liu, Jing2" <jing2.liu@...el.com>,
        LKML <linux-kernel@...r.kernel.org>,
        "x86@...nel.org" <x86@...nel.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Arjan van de Ven <arjan@...ux.intel.com>,
        Jing Liu <jing2.liu@...ux.intel.com>,
        "seanjc@...gle.com" <seanjc@...gle.com>,
        "Cooper, Andrew" <andrew.cooper3@...rix.com>,
        "Bae, Chang Seok" <chang.seok.bae@...el.com>
Subject: RE: Thoughts of AMX KVM support based on latest kernel

Tian,

On Wed, Nov 17 2021 at 10:15, Tian, Kevin wrote:
> We are not sure whether such trick is worthwhile, since a sane
> guest shouldn't set XFD[AMX]=1 before storing the AMX state. This
> is why we want to seek SDM change to mark out that the software
> should not assume XTILEDATA is still valid when XFD[AMX]=1.

Yes, please. Anything else is just causing too much hackery for no
value.

Thanks,

        tglx