linux-kernel - Re: [PATCH] x86/mm: Check cc_vendor when printing memory encryption info

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Message-ID: <58abbc79-64d4-41f9-9fd2-1de7826fbbf6@linux.microsoft.com>
Date:   Thu, 9 Nov 2023 17:35:39 +0100
From:   Jeremi Piotrowski <jpiotrowski@...ux.microsoft.com>
To:     Dave Hansen <dave.hansen@...el.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>,
        linux-kernel@...r.kernel.org,
        Michael Kelley <mhklinux@...look.com>,
        Dexuan Cui <decui@...rosoft.com>
Cc:     linux-hyperv@...r.kernel.org, stefan.bader@...onical.com,
        tim.gardner@...onical.com, roxana.nicolescu@...onical.com,
        cascardo@...onical.com, kys@...rosoft.com, haiyangz@...rosoft.com,
        wei.liu@...nel.org, kirill.shutemov@...ux.intel.com,
        sashal@...nel.org
Subject: Re: [PATCH] x86/mm: Check cc_vendor when printing memory encryption
 info

On 09/11/2023 17:25, Dave Hansen wrote:
> On 11/9/23 08:14, Jeremi Piotrowski wrote:
> ...
>>  	pr_info("Memory Encryption Features active:");
>>  
>> -	if (cpu_feature_enabled(X86_FEATURE_TDX_GUEST)) {
>> +	if (cc_vendor == CC_VENDOR_INTEL) {
>>  		pr_cont(" Intel TDX\n");
>>  		return;
>>  	}
> 
> Why aren't these guests setting X86_FEATURE_TDX_GUEST?

They could if we can confirm that the code gated behind
cpu_feature_enabled(X86_FEATURE_TDX_GUEST) is correct when running with TD partitioning.

It still makes sense to have these prints based on the cc_xxx abstractions.

Jeremi