linux-kernel - RE: [patch 13/31] x86/fpu: Move KVMs FPU swapping to FPU core

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <BL0PR11MB3252466D4A10A141F025F425A9B89@BL0PR11MB3252.namprd11.prod.outlook.com>
Date:   Thu, 14 Oct 2021 08:21:02 +0000
From:   "Liu, Jing2" <jing2.liu@...el.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Paolo Bonzini <pbonzini@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>
CC:     "x86@...nel.org" <x86@...nel.org>,
        "Bae, Chang Seok" <chang.seok.bae@...el.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "Arjan van de Ven" <arjan@...ux.intel.com>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "Nakajima, Jun" <jun.nakajima@...el.com>,
        Jing Liu <jing2.liu@...ux.intel.com>,
        "seanjc@...gle.com" <seanjc@...gle.com>
Subject: RE: [patch 13/31] x86/fpu: Move KVMs FPU swapping to FPU core



> > 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?
> 
> Just making that function usable without a proper design how this should
> work at all does not solve anything.
> 
> We first need a conclusion vs. buffer reallocation.
> 
> 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 into
> 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

> 
> Thanks,
> 
>         tglx