linux-kernel - Re: [patch V3 17/66] x86/fpu: Make copy_xstate_to_kernel() usable for [x]fpregs

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Date:   Mon, 21 Jun 2021 14:32:18 +0200
From:   Borislav Petkov <bp@...e.de>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Tony Luck <tony.luck@...el.com>,
        Yu-cheng Yu <yu-cheng.yu@...el.com>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Kan Liang <kan.liang@...ux.intel.com>
Subject: Re: [patch V3 17/66] x86/fpu: Make copy_xstate_to_kernel() usable
 for [x]fpregs_get()

On Fri, Jun 18, 2021 at 04:18:40PM +0200, Thomas Gleixner wrote:
> When xsave with init state optimization is used then a component's state
> in the task's xsave buffer can be stale when the corresponding feature bit
> is not set.
> 
> fpregs_get() and xfpregs_get() invoke fpstate_sanitize_xstate() to update
> the task's xsave buffer before retrieving the FX or FP state. That's just
> duplicated code as copy_xstate_to_kernel() already handles this correctly.
> 
> Add a copy mode argument to the function which allows to restrict the state
> copy to the FP and SSE features.
> 
> Also rename the function to copy_xstate_to_uabi_buf() so the name reflects
> what it is doing.
> 
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> ---
> V3: Rename to copy_xstate_to_uabi_buf() - Boris
> V2: New patch
> ---
>  arch/x86/include/asm/fpu/xstate.h |   12 +++++++++-
>  arch/x86/kernel/fpu/regset.c      |    2 -
>  arch/x86/kernel/fpu/xstate.c      |   42 ++++++++++++++++++++++++++++----------
>  3 files changed, 42 insertions(+), 14 deletions(-)

Reviewed-by: Borislav Petkov <bp@...e.de>

-- 
Regards/Gruss,
    Boris.

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