linux-kernel - Re: [PATCH] x86/coco, x86/sev: Use cpu_feature

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Date:   Tue, 5 Dec 2023 15:46:19 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Cc:     Tom Lendacky <thomas.lendacky@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        linux-coco@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86/coco, x86/sev: Use cpu_feature_enabled() to detect
 SEV guest flavor

On Tue, Dec 05, 2023 at 05:37:38PM +0300, Kirill A. Shutemov wrote:
> The SEV code uses cc_platform_has() checks to detect the SEV flavor.
> However, these checks can sometimes produce false positives depending on
> the context.
> 
> For example, sev_map_percpu_data() uses CC_ATTR_GUEST_MEM_ENCRYPT to
> detect SEV guest, but this check will also pass for TDX guests.

Well, a function prefixed with "sev_" should check cc_vendor first...

-- 
Regards/Gruss,
    Boris.

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