Re: [PATCH v2 05/39] x86/fpu/xstate: Introduce CET MSR and XSAVES supervisor states

[Kees Cook]

On Thu, Sep 29, 2022 at 03:29:02PM -0700, Rick Edgecombe wrote:
> [...]
> xfeatures. So refactor these check's by having XCHECK_SZ() set a bool when
> it actually check's the xfeature. This ends up exceeding 80 chars, but was

Spelling nit through-out all patches: possessive used for plurals. E.g.
the above "check's" instances should be "checks". Please review all the
documentation and commit logs; it shows up a lot. :)

> [...]
> diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
> index c8340156bfd2..5e6a4867fd05 100644
> --- a/arch/x86/kernel/fpu/xstate.c
> +++ b/arch/x86/kernel/fpu/xstate.c
> @@ -39,26 +39,26 @@
>   */
>  static const char *xfeature_names[] =
>  {
> -	"x87 floating point registers"	,
> -	"SSE registers"			,
> -	"AVX registers"			,
> -	"MPX bounds registers"		,
> -	"MPX CSR"			,
> -	"AVX-512 opmask"		,
> -	"AVX-512 Hi256"			,
> -	"AVX-512 ZMM_Hi256"		,
> -	"Processor Trace (unused)"	,
> -	"Protection Keys User registers",
> -	"PASID state",
> -	"unknown xstate feature"	,
> -	"unknown xstate feature"	,
> -	"unknown xstate feature"	,
> -	"unknown xstate feature"	,
> -	"unknown xstate feature"	,
> -	"unknown xstate feature"	,
> -	"AMX Tile config"		,
> -	"AMX Tile data"			,
> -	"unknown xstate feature"	,
> +	"x87 floating point registers"			,
> +	"SSE registers"					,
> +	"AVX registers"					,
> +	"MPX bounds registers"				,
> +	"MPX CSR"					,
> +	"AVX-512 opmask"				,
> +	"AVX-512 Hi256"					,
> +	"AVX-512 ZMM_Hi256"				,
> +	"Processor Trace (unused)"			,
> +	"Protection Keys User registers"		,
> +	"PASID state"					,
> +	"Control-flow User registers"			,
> +	"Control-flow Kernel registers (unused)"	,
> +	"unknown xstate feature"			,
> +	"unknown xstate feature"			,
> +	"unknown xstate feature"			,
> +	"unknown xstate feature"			,
> +	"AMX Tile config"				,
> +	"AMX Tile data"					,
> +	"unknown xstate feature"			,

What a strange style. Why not just leave the commas after the " ? Then
these kinds of multi-line updates aren't needed in the future.

> [...]
> -	/*
> -	 * Make *SURE* to add any feature numbers in below if
> -	 * there are "holes" in the xsave state component
> -	 * numbers.
> -	 */
> -	if ((nr < XFEATURE_YMM) ||
> -	    (nr >= XFEATURE_MAX) ||
> -	    (nr == XFEATURE_PT_UNIMPLEMENTED_SO_FAR) ||
> -	    ((nr >= XFEATURE_RSRVD_COMP_11) && (nr <= XFEATURE_RSRVD_COMP_16))) {
> +	if (!chked) {
>  		WARN_ONCE(1, "no structure for xstate: %d\n", nr);
>  		XSTATE_WARN_ON(1);
>  		return false;

This clean-up feels like it should be part of a separate patch, but
okay. :)

Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>

-- 
Kees Cook