linux-kernel - Re: [PATCH v2 06/14] x86/microcode/intel: Expose microcode_sanity

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Date:   Fri, 11 Nov 2022 15:33:48 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Jithu Joseph <jithu.joseph@...el.com>
Cc:     hdegoede@...hat.com, markgross@...nel.org, tglx@...utronix.de,
        mingo@...hat.com, dave.hansen@...ux.intel.com, x86@...nel.org,
        hpa@...or.com, gregkh@...uxfoundation.org, ashok.raj@...el.com,
        tony.luck@...el.com, linux-kernel@...r.kernel.org,
        platform-driver-x86@...r.kernel.org, patches@...ts.linux.dev,
        ravi.v.shankar@...el.com, thiago.macieira@...el.com,
        athenas.jimenez.gonzalez@...el.com, sohil.mehta@...el.com
Subject: Re: [PATCH v2 06/14] x86/microcode/intel: Expose
 microcode_sanity_check()

On Mon, Nov 07, 2022 at 02:53:15PM -0800, Jithu Joseph wrote:
> IFS test image carries the same microcode header as regular Intel
> microcode blobs. Microcode blobs  use header version of 1,
> whereas IFS test images will use header version of 2.
> 
> microcode_sanity_check() can be used by IFS driver to perform
> sanity check of the IFS test images too.
> 
> Refactor header version as a parameter, move it to cpu/intel.c
> and expose this function. Qualify the function name with intel.

Same comments as before.

> Reviewed-by: Tony Luck <tony.luck@...el.com>
> Reviewed-by: Ashok Raj <ashok.raj@...el.com>
> Signed-off-by: Jithu Joseph <jithu.joseph@...el.com>
> ---
>  arch/x86/include/asm/cpu.h             |   1 +
>  arch/x86/include/asm/microcode_intel.h |   1 +
>  arch/x86/kernel/cpu/intel.c            | 100 ++++++++++++++++++++++++
>  arch/x86/kernel/cpu/microcode/intel.c  | 102 +------------------------
>  4 files changed, 104 insertions(+), 100 deletions(-)
> 
> diff --git a/arch/x86/include/asm/cpu.h b/arch/x86/include/asm/cpu.h
> index e853440b5c65..4aff5f263973 100644
> --- a/arch/x86/include/asm/cpu.h
> +++ b/arch/x86/include/asm/cpu.h
> @@ -96,5 +96,6 @@ static inline bool intel_cpu_signatures_match(unsigned int s1, unsigned int p1,
>  
>  extern u64 x86_read_arch_cap_msr(void);
>  int intel_find_matching_signature(void *mc, unsigned int csig, int cpf);
> +int intel_microcode_sanity_check(void *mc, bool print_err, int hdr_ver);
>  
>  #endif /* _ASM_X86_CPU_H */
> diff --git a/arch/x86/include/asm/microcode_intel.h b/arch/x86/include/asm/microcode_intel.h
> index 4c92cea7e4b5..6626744c577b 100644
> --- a/arch/x86/include/asm/microcode_intel.h
> +++ b/arch/x86/include/asm/microcode_intel.h
> @@ -41,6 +41,7 @@ struct extended_sigtable {
>  #define DEFAULT_UCODE_TOTALSIZE (DEFAULT_UCODE_DATASIZE + MC_HEADER_SIZE)
>  #define EXT_HEADER_SIZE		(sizeof(struct extended_sigtable))
>  #define EXT_SIGNATURE_SIZE	(sizeof(struct extended_signature))
> +#define MICROCODE_HEADER_VER_UCODE	1

"MICROCODE" ... "UCODE" - too much.

And "header version" sounds wrong when all you wanna say is, this header
is of this or that *type*. So you simply do:

#define MC_HEADER_TYPE_MICROCODE	1
#define MC_HEADER_TYPE_IFS		2

and that's it.

>  #define get_totalsize(mc) \
>  	(((struct microcode_intel *)mc)->hdr.datasize ? \
> diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
> index b6f9210fb31a..f8a5a25ab502 100644
> --- a/arch/x86/kernel/cpu/intel.c
> +++ b/arch/x86/kernel/cpu/intel.c
> @@ -245,6 +245,106 @@ int intel_find_matching_signature(void *mc, unsigned int csig, int cpf)
>  }
>  EXPORT_SYMBOL_GPL(intel_find_matching_signature);
>  
> +int intel_microcode_sanity_check(void *mc, bool print_err, int hdr_ver)

This is not how this is done:

1st patch: *only* mechanical code move, no semantic or functional changes
whatsoever.

2nd patch: Add semantical/functional changes.

Also, in the second patch, pls put a kernel-doc comment over the
function to explain what hdr_type - not hdr_ver - means here.

Thx.

-- 
Regards/Gruss,
    Boris.

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