linux-kernel - Re: [PATCH v4] x86/cpu: clear SME feature flag when not in use

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Message-ID: <579aec6b-78d1-57af-8e17-59cbe59f168a@amd.com>
Date:   Wed, 16 Feb 2022 07:41:59 -0600
From:   "Limonciello, Mario" <mario.limonciello@....com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>,
        Kees Cook <keescook@...omium.org>,
        Thomas Lendacky <Thomas.Lendacky@....com>, hughsient@...il.com,
        Martin Fernandez <martin.fernandez@...ypsium.com>,
        linux-kernel@...r.kernel.org, Brijesh Singh <brijesh.singh@....com>
Subject: Re: [PATCH v4] x86/cpu: clear SME feature flag when not in use

On 2/16/2022 04:33, Borislav Petkov wrote:
> On Tue, Feb 15, 2022 at 09:44:46PM -0600, Mario Limonciello wrote:
>> @@ -607,6 +609,9 @@ static void early_detect_mem_encrypt(struct cpuinfo_x86 *c)
>>   		if (IS_ENABLED(CONFIG_X86_32))
>>   			goto clear_all;
>>   
>> +		if (!sme_me_mask)
>> +			setup_clear_cpu_cap(X86_FEATURE_SME);
> 
> Why not "goto clear_all;" ?
> 

"clear_all" clears SEV and SEV_ES as well which as pointed out in v2 is 
incorrect.