linux-kernel - Re: [PATCHv3 13/32] x86/tdx: Detect TDX at early kernel decompression time

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Message-ID: <20220221135334.zzcozxu6vyskxjzo@black.fi.intel.com>
Date:   Mon, 21 Feb 2022 16:53:34 +0300
From:   "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To:     Cyrill Gorcunov <gorcunov@...il.com>
Cc:     tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
        dave.hansen@...el.com, luto@...nel.org, peterz@...radead.org,
        sathyanarayanan.kuppuswamy@...ux.intel.com, aarcange@...hat.com,
        ak@...ux.intel.com, dan.j.williams@...el.com, david@...hat.com,
        hpa@...or.com, jgross@...e.com, jmattson@...gle.com,
        joro@...tes.org, jpoimboe@...hat.com, knsathya@...nel.org,
        pbonzini@...hat.com, sdeep@...are.com, seanjc@...gle.com,
        tony.luck@...el.com, vkuznets@...hat.com, wanpengli@...cent.com,
        x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCHv3 13/32] x86/tdx: Detect TDX at early kernel
 decompression time

On Mon, Feb 21, 2022 at 02:37:29PM +0300, Cyrill Gorcunov wrote:
> On Fri, Feb 18, 2022 at 07:16:59PM +0300, Kirill A. Shutemov wrote:
> ...
> > 
> > +
> > +void early_tdx_detect(void)
> > +{
> > +	u32 eax, sig[3];
> > +
> > +	cpuid_count(TDX_CPUID_LEAF_ID, 0, &eax, &sig[0], &sig[2],  &sig[1]);
> > +
> > +	if (memcmp(TDX_IDENT, sig, 12))
> > +		return;
> 
> Maybe worth to guard ourself, like
> 
> 	BUILD_BUG_ON(sizeof(sig) != (sizeof(TDX_IDENT)-1));
> 	if (memcmp(TDX_IDENT, sig, sizeof(sig))
> 		return;

Sure. Will do.

-- 
 Kirill A. Shutemov