linux-kernel - [PATCH v4 16/16] x86/cpu: Make LAM depend on LASS

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Message-ID: <20240710160655.3402786-17-alexander.shishkin@linux.intel.com>
Date: Wed, 10 Jul 2024 19:06:52 +0300
From: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
To: Andy Lutomirski <luto@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
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	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
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Subject: [PATCH v4 16/16] x86/cpu: Make LAM depend on LASS

To prevent exploits for Spectre based on LAM as demonstrated by the
whitepaper [1], make LAM depend on LASS, which avoids this type of
vulnerability.

[1] https://download.vusec.net/papers/slam_sp24.pdf

Signed-off-by: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
---
 arch/x86/kernel/cpu/cpuid-deps.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/kernel/cpu/cpuid-deps.c b/arch/x86/kernel/cpu/cpuid-deps.c
index 22612e01ec2e..8986e990beb0 100644
--- a/arch/x86/kernel/cpu/cpuid-deps.c
+++ b/arch/x86/kernel/cpu/cpuid-deps.c
@@ -85,6 +85,7 @@ static const struct cpuid_dep cpuid_deps[] = {
 	{ X86_FEATURE_FRED,			X86_FEATURE_LKGS      },
 	{ X86_FEATURE_FRED,			X86_FEATURE_WRMSRNS   },
 	{ X86_FEATURE_LASS,			X86_FEATURE_SMAP      },
+	{ X86_FEATURE_LAM,			X86_FEATURE_LASS      },
 	{}
 };
 
-- 
2.43.0