Re: [PATCH v9 33/43] x86/compressed: Add SEV-SNP feature detection/setup

From: Borislav Petkov <bp@alien8.de>
To: Michael Roth <michael.roth@amd.com>
Cc: Brijesh Singh <brijesh.singh@amd.com>,
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Subject: Re: [PATCH v9 33/43] x86/compressed: Add SEV-SNP feature detection/setup
Date: Tue, 8 Feb 2022 16:02:02 +0100	[thread overview]
Message-ID: <YgKF6kzR87WuXj/a@zn.tnic> (raw)
In-Reply-To: <20220208135009.7rfrau33kxivx5h3@amd.com>

On Tue, Feb 08, 2022 at 07:50:09AM -0600, Michael Roth wrote:
> I'm assuming that would be considered 'non-static' since it would need
> to be exported if sev-shared.c was compiled separately instead of
> directly #include'd.

No, that one can lose the prefix too. We'll cross that bridge when we
get to it.

> And then there's also these which are static helpers that are only used
> within sev-shared.c:
> 
>   snp_cpuid_info_get_ptr()

So looking at that one - and it felt weird reading that code because it
said "cpuid_info" but that's not an "info" - that should be:

struct snp_cpuid_table {
        u32 count;
        u32 __reserved1;
        u64 __reserved2;
        struct snp_cpuid_fn fn[SNP_CPUID_COUNT_MAX];
} __packed;

just call it what it is - a SNP CPUID *table*.

And then you can have

	const struct snp_cpuid_table *cpuid_tbl = snp_cpuid_get_table();

and that makes it crystal clear what this does.

>   snp_cpuid_calc_xsave_size()
>   snp_cpuid_get_validated_func()
>
>   snp_cpuid_check_range()

You can merge that small function into its only call site and put a
comment above the code:

	/* Check function is within the supported CPUID leafs ranges */

>   snp_cpuid_hv()
>   snp_cpuid_postprocess()
>   snp_cpuid()
> 
> but in those cases it seems useful to keep them grouped under the
> snp_cpuid_* prefix since they become ambiguous otherwise, and
> just using cpuid_* as a prefix (or suffix/etc) makes it unclear
> that they are only used for SNP and not for general CPUID handling.
> Should we leave those as-is?

Yap, the rest make sense to denote to what functionality they belong to.

Thx.

-- 
Regards/Gruss,
    Boris.

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