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  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]
Date:   Thu, 19 Nov 2020 21:02:26 -0800
From:   Andy Lutomirski <luto@...nel.org>
To:     "Chang S. Bae" <chang.seok.bae@...el.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>, Borislav Petkov <bp@...e.de>,
        Andrew Lutomirski <luto@...nel.org>, X86 ML <x86@...nel.org>,
        Len Brown <len.brown@...el.com>,
        Dave Hansen <dave.hansen@...el.com>,
        "Liu, Jing2" <jing2.liu@...el.com>,
        "Ravi V. Shankar" <ravi.v.shankar@...el.com>,
        LKML <linux-kernel@...r.kernel.org>,
        "open list:DOCUMENTATION" <linux-doc@...r.kernel.org>
Subject: Re: [PATCH v2 22/22] x86/fpu/xstate: Introduce boot-parameters for
 control some state component support

On Thu, Nov 19, 2020 at 3:37 PM Chang S. Bae <chang.seok.bae@...el.com> wrote:
>
> Rename XFEATURE_MASK_USER_SUPPORTED to XFEATURE_MASK_USER_ENABLED to
> literally align with new boot-parameters.
>
> "xstate.disable=0x60000" will disable AMX on a system that has AMX compiled
> into XFEATURE_MASK_USER_ENABLED.
>
> "xstate.enable=0x60000" will enable AMX on a system that does NOT have AMX
> compiled into XFEATURE_MASK_USER_ENABLED (assuming the kernel is new enough
> to support this feature).
>

What's the purpose of xstate.enable?  I can't really imagine it's
useful for AMX.  I suppose it could be useful for hypothetical
post-AMX features, but that sounds extremely dangerous.  Intel has
changed its strategy so many times on XSTATE extensibility that I find
it quite hard to believe that supporting unknown states is wise.

Powered by blists - more mailing lists