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From:   "Liu, Jing2" <jing2.liu@intel.com>
To:     Thomas Gleixner <tglx@linutronix.de>,
        Paolo Bonzini <pbonzini@redhat.com>,
        LKML <linux-kernel@vger.kernel.org>
CC:     "x86@kernel.org" <x86@kernel.org>,
        "Bae, Chang Seok" <chang.seok.bae@intel.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        "Arjan van de Ven" <arjan@linux.intel.com>,
        "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
        "Nakajima, Jun" <jun.nakajima@intel.com>,
        Jing Liu <jing2.liu@linux.intel.com>,
        "seanjc@google.com" <seanjc@google.com>
Subject: RE: [patch 13/31] x86/fpu: Move KVMs FPU swapping to FPU core
Thread-Topic: [patch 13/31] x86/fpu: Move KVMs FPU swapping to FPU core
Thread-Index: AQHXv42x8Iw8v1bdT0WqN+QXiZLaIqvQcYTggACYyYCAAR5hgA==
Date:   Thu, 14 Oct 2021 08:21:02 +0000
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> > 1. KVM dynamic allocation API:
> > Since KVM also uses dynamic allocation, after KVM detects guest
> > requesting AMX by #NM trap, KVM need alloc extra buffer for this
> > vcpu's current->thread.fpu.fpstate and guest_fpu related.
> > So far, the kernel itself has such API like fpstate_realloc(), but
> > it's static. How about making a common function usable for KVM?
>=20
> Just making that function usable without a proper design how this should
> work at all does not solve anything.
>=20
> We first need a conclusion vs. buffer reallocation.
>=20
> Once that is sorted then we can create proper infrastructure for that in =
the
> FPU core code and not just expose a random function to KVM and hack it in=
to
> submssion.
Yes, we need a consensus on the way we choose and then to see if need a
kernel function for KVM usage.

Thanks,
Jing

>=20
> Thanks,
>=20
>         tglx