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Date:   Thu, 17 Feb 2022 16:24:05 +0100
From:   Borislav Petkov <bp@alien8.de>
To:     "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc:     Dave Hansen <dave.hansen@intel.com>,
        Tom Lendacky <thomas.lendacky@amd.com>, tglx@linutronix.de,
        mingo@redhat.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,
        hpa@zytor.com, jgross@suse.com, jmattson@google.com,
        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: [PATCHv2 22/29] x86/tdx: Make pages shared in ioremap()
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On Wed, Feb 16, 2022 at 06:37:03PM +0300, Kirill A. Shutemov wrote:
> 	bool cc_platform_has(enum cc_attr attr)
> 	{
> 		if (cpu_feature_enabled(X86_FEATURE_TDX_GUEST))
> 			return intel_cc_platform_has(attr);
> 		else if (cc_mask)
> 			return amd_cc_platform_has(attr);

It is exactly stuff like that I'd like to avoid because that is
dependent on the order the test happens.

It would be a lot more robust if this did:

	switch (cc_vendor) {
	case INTEL:  return intel_cc_platform_has(attr);
	case AMD:    return amd_cc_platform_has(attr);
	case HYPERV: return hyperv_cc_platform_has(attr);
	default: return false;
	}

-- 
Regards/Gruss,
    Boris.

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