linux-kernel - Re: [PATCH v10 03/28] x86/fpu/xstate: Modify state copy helpers to handle both static and dynamic buffers

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Message-ID: <D6BE7E70-896D-4192-86CD-F075705B2DBB@intel.com>
Date:   Sun, 3 Oct 2021 22:42:22 +0000
From:   "Bae, Chang Seok" <chang.seok.bae@...el.com>
To:     Thomas Gleixner <tglx@...utronix.de>
CC:     "bp@...e.de" <bp@...e.de>, "Lutomirski, Andy" <luto@...nel.org>,
        "mingo@...nel.org" <mingo@...nel.org>,
        "x86@...nel.org" <x86@...nel.org>,
        "Brown, Len" <len.brown@...el.com>,
        "lenb@...nel.org" <lenb@...nel.org>,
        "Hansen, Dave" <dave.hansen@...el.com>,
        "Macieira, Thiago" <thiago.macieira@...el.com>,
        "Liu, Jing2" <jing2.liu@...el.com>,
        "Shankar, Ravi V" <ravi.v.shankar@...el.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v10 03/28] x86/fpu/xstate: Modify state copy helpers to
 handle both static and dynamic buffers

On Oct 1, 2021, at 05:47, Thomas Gleixner <tglx@...utronix.de> wrote:
> On Wed, Aug 25 2021 at 08:53, Chang S. Bae wrote:
>> Have all the functions copying XSTATE take a struct fpu * pointer in
>> preparation for dynamic state buffer support.
> 
> Which is something different than the subject line claims to do and
> still does not explain why this code needs access to struct fpu later
> on.

This was liked by Boris [1]:

    What I would've written is:

    "Have all functions handling FPU state take a struct fpu * pointer in
     preparation for dynamic state buffer support."

    Plain and simple.

How about this (as similar to [2]):

    “To prepare dynamic features, change XSTATE copy functions' arguments to a
     struct fpu * pointer instead of a struct fpregs_state * pointer.  It will
     have new fields for dynamic features.”

Along with this title:

    “Prepare XSTATE copy functions to handle dynamic features”

Thanks,
Chang

[1] https://lore.kernel.org/lkml/20210115131802.GD11337@zn.tnic/
[2]https://lore.kernel.org/lkml/5767911A-6F1F-4EDE-92A4-D4C3E5A3AABF@intel.com/