Re: [patch V3 56/66] x86/fpu: Dont store PKRU in xstate in fpu_reset_fpstate()

[Borislav Petkov]

On Fri, Jun 18, 2021 at 04:19:19PM +0200, Thomas Gleixner wrote:
> PKRU for a task is stored in task->thread.pkru when the task is scheduled
> out. For 'current' the authoritative source of PKRU is the hardware.
> 
> fpu_reset_fpstate() has two callers:
> 
>   1) fpu__clear_user_states() for !FPU systems. For those PKRU is irrelevant
> 
>   2) fpu_flush_thread() which is invoked from flush_thread(). flush_thread()
>      resets the hardware to the kernel restrictive default value.
> 
> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> ---
>  arch/x86/kernel/fpu/core.c |   22 ++++------------------
>  1 file changed, 4 insertions(+), 18 deletions(-)

Reviewed-by: Borislav Petkov <bp@xxxxxxx>

-- 
Regards/Gruss,
    Boris.

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