linux-kernel - Re: [PATCH 1/2] x86: Use CPUID 0x8000001f to confirm SME availability

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Message-ID: <d476d448-cd68-0c93-c98c-4f952d7caef6@amd.com>
Date:   Fri, 11 Feb 2022 15:09:12 -0600
From:   Tom Lendacky <thomas.lendacky@....com>
To:     "Limonciello, Mario" <mario.limonciello@....com>,
        Borislav Petkov <bp@...en8.de>,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>
Cc:     Kees Cook <keescook@...omium.org>, hughsient@...il.com,
        Martin Fernandez <martin.fernandez@...ypsium.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] x86: Use CPUID 0x8000001f to confirm SME availability

On 2/11/22 13:51, Limonciello, Mario wrote:
> On 2/11/2022 08:55, Tom Lendacky wrote:
>> On 2/10/22 23:36, Mario Limonciello wrote:

>      1254:       f6 45 d8 01             testb  $0x1,-0x28(%rbp)
>      1258:       74 02                   je     125c <stop_this_cpu+0x8c>
>      125a:       0f 09                   wbinvd
>      125c:       eb 07                   jmp    1265 <stop_this_cpu+0x95>
>      125e:       0f 00 2d 00 00 00 00    verw   0x0(%rip)        # 1265 
> <stop_this_cpu+0x95>
>      1265:       f4                      hlt
>      1266:       eb f4                   jmp    125c <stop_this_cpu+0x8c>

That appears to be the same as today after the WBINVD is issued, so should 
be good.

Thanks,
Tom

>