linux-kernel - [PATCH] x86/CPU/AMD: Ensure clearing of SME/SEV features is maintained

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Date:   Wed, 15 Jan 2020 16:05:16 -0600
From:   Tom Lendacky <thomas.lendacky@....com>
To:     linux-kernel@...r.kernel.org, x86@...nel.org
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Joerg Roedel <joro@...tes.org>,
        Brijesh Singh <brijesh.singh@....com>, stable@...r.kernel.org
Subject: [PATCH] x86/CPU/AMD: Ensure clearing of SME/SEV features is maintained

If the SME and SEV features are present via CPUID, but memory encryption
support is not enabled (MSR 0xC001_0010[23]), the features are cleared
using clear_cpu_cap(). However, if get_cpu_cap() is later called, these
features will be reset back to present, which is not desired.

Change from using clear_cpu_cap() to setup_clear_cpu_cap() so that the
clearing of the features is maintained.

Cc: <stable@...r.kernel.org> # 4.16.x-
Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
---
 arch/x86/kernel/cpu/amd.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 90f75e515876..62c30279be77 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -615,9 +615,9 @@ static void early_detect_mem_encrypt(struct cpuinfo_x86 *c)
 		return;
 
 clear_all:
-		clear_cpu_cap(c, X86_FEATURE_SME);
+		setup_clear_cpu_cap(X86_FEATURE_SME);
 clear_sev:
-		clear_cpu_cap(c, X86_FEATURE_SEV);
+		setup_clear_cpu_cap(X86_FEATURE_SEV);
 	}
 }
 
-- 
2.17.1