linux-kernel - [PATCH 2/2] x86/cpu: clear SME/SEV/SEV

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Message-ID: <20220211053652.64655-2-mario.limonciello@amd.com>
Date:   Thu, 10 Feb 2022 23:36:52 -0600
From:   Mario Limonciello <mario.limonciello@....com>
To:     Borislav Petkov <bp@...en8.de>,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>
CC:     Kees Cook <keescook@...omium.org>,
        Thomas Lendacky <Thomas.Lendacky@....com>,
        <hughsient@...il.com>,
        Martin Fernandez <martin.fernandez@...ypsium.com>,
        <linux-kernel@...r.kernel.org>,
        "Mario Limonciello" <mario.limonciello@....com>
Subject: [PATCH 2/2] x86/cpu: clear SME/SEV/SEV_ES features when not in use

Currently SME/SEV/SEV_ES features are reflective of whether the CPU
supports the features but not whether they have been activated by the
kernel.

Change this around to clear the features if the kernel is not using
them so userspace can determine if they are available and in use
from `/proc/cpuinfo`.

Signed-off-by: Mario Limonciello <mario.limonciello@....com>
---
 arch/x86/kernel/cpu/amd.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 4edb6f0f628c..4a7d4801fa0b 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -611,12 +611,20 @@ static void early_detect_mem_encrypt(struct cpuinfo_x86 *c)
 		if (!(msr & MSR_K7_HWCR_SMMLOCK))
 			goto clear_sev;
 
+		if (!cc_platform_has(CC_ATTR_MEM_ENCRYPT))
+			goto clear_all;
+		if (!cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT))
+			goto clear_sev;
+		if (!cc_platform_has(CC_ATTR_GUEST_STATE_ENCRYPT))
+			goto clear_sev_es;
+
 		return;
 
 clear_all:
 		setup_clear_cpu_cap(X86_FEATURE_SME);
 clear_sev:
 		setup_clear_cpu_cap(X86_FEATURE_SEV);
+clear_sev_es:
 		setup_clear_cpu_cap(X86_FEATURE_SEV_ES);
 	}
 }
-- 
2.34.1