Re: [PATCH v3 07/10] x86/fpu/xstate: Update copy_kernel_to_xregs_err() for XSAVES supervisor states

[Borislav Petkov]

On Sat, Mar 28, 2020 at 09:43:04AM -0700, Yu-cheng Yu wrote:
> The function copy_kernel_to_xregs_err() uses XRSTOR, which can work with
> standard or compacted format without supervisor xstates.  However, when
> supervisor xstates are present, XRSTORS must be used.  Fix it by using
> XRSTORS when XSAVES is enabled.
> 
> I also considered if there were additional cases where XRSTOR might be
> mistakenly called instead of XRSTORS.  There are only three XRSTOR sites
> in kernel:
> 
> 1. copy_kernel_to_xregs_booting(), already switches between XRSTOR and
>    XRSTORS based on X86_FEATURE_XSAVES.
> 2. copy_user_to_xregs(), which *needs* XRSTOR because it is copying from
>    userspace and must never copy supervisor state with XRSTORS.
> 3. copy_kernel_to_xregs_err() mistakenly used XRSTOR only.  Fixed in
>    this patch.

Avoid having "This patch" or "This commit" in the commit message. It is
tautologically useless.

Also, do

$ git grep 'This patch' Documentation/process

for more details.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette