Re: [PATCH v8 03/27] x86/fpu/xstate: Change names to separate XSAVES system and user states

[Borislav Petkov]

On Tue, Aug 13, 2019 at 01:52:01PM -0700, Yu-cheng Yu wrote:
> Control-flow Enforcement (CET) MSR contents are XSAVES system states.
> To support CET, introduce XSAVES system states first.
> 
> XSAVES is a "supervisor" instruction and, comparing to XSAVE, saves
> additional "supervisor" states that can be modified only from CPL 0.
> However, these states are per-task and not kernel's own.  Rename
> "supervisor" states to "system" states to clearly separate them from
> "user" states.
> 
> Signed-off-by: Yu-cheng Yu <yu-cheng.yu@xxxxxxxxx>
> ---
>  arch/x86/include/asm/fpu/internal.h |  4 +-
>  arch/x86/include/asm/fpu/xstate.h   | 20 +++----
>  arch/x86/kernel/fpu/init.c          |  2 +-
>  arch/x86/kernel/fpu/signal.c        | 10 ++--
>  arch/x86/kernel/fpu/xstate.c        | 86 ++++++++++++++---------------
>  5 files changed, 60 insertions(+), 62 deletions(-)

...

> diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
> index e5cb67d67c03..d560e8861a3c 100644
> --- a/arch/x86/kernel/fpu/xstate.c
> +++ b/arch/x86/kernel/fpu/xstate.c
> @@ -54,13 +54,16 @@ static short xsave_cpuid_features[] __initdata = {
>  };
>  
>  /*
> - * Mask of xstate features supported by the CPU and the kernel:
> + * XSAVES system states can only be modified from CPL 0 and saved by
> + * XSAVES.  The rest are user states.  The following is a mask of
> + * supported user state features derived from boot_cpu_has() and

...derived from detected CPUID feature flags and
SUPPORTED_XFEATURES_MASK.

-- 
Regards/Gruss,
    Boris.

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