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Date:   Mon, 21 Feb 2022 14:37:29 +0300
From:   Cyrill Gorcunov <gorcunov@gmail.com>
To:     "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc:     tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
        dave.hansen@intel.com, luto@kernel.org, peterz@infradead.org,
        sathyanarayanan.kuppuswamy@linux.intel.com, aarcange@redhat.com,
        ak@linux.intel.com, dan.j.williams@intel.com, david@redhat.com,
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        joro@8bytes.org, jpoimboe@redhat.com, knsathya@kernel.org,
        pbonzini@redhat.com, sdeep@vmware.com, seanjc@google.com,
        tony.luck@intel.com, vkuznets@redhat.com, wanpengli@tencent.com,
        x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCHv3 13/32] x86/tdx: Detect TDX at early kernel
 decompression time
Message-ID: <YhN5edJQ+LkVc0us@grain>
References: <20220218161718.67148-1-kirill.shutemov@linux.intel.com>
 <20220218161718.67148-14-kirill.shutemov@linux.intel.com>
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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;