linux-kernel - [PATCH v4 13/16] x86/cpu: Set LASS CR4 bit as pinning sensitive

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Message-ID: <20240710160655.3402786-14-alexander.shishkin@linux.intel.com>
Date: Wed, 10 Jul 2024 19:06:49 +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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Cc: Jonathan Corbet <corbet@....net>,
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Subject: [PATCH v4 13/16] x86/cpu: Set LASS CR4 bit as pinning sensitive

From: Yian Chen <yian.chen@...el.com>

Security features such as LASS are not expected to be disabled once
initialized. Add LASS to the CR4 pinned mask.

Signed-off-by: Yian Chen <yian.chen@...el.com>
Signed-off-by: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Reviewed-by: Tony Luck <tony.luck@...el.com>
---
 arch/x86/kernel/cpu/common.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index c93c59a27dfa..3dc443c349f0 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -407,7 +407,8 @@ static __always_inline void setup_lass(struct cpuinfo_x86 *c)
 
 /* These bits should not change their value after CPU init is finished. */
 static const unsigned long cr4_pinned_mask = X86_CR4_SMEP | X86_CR4_SMAP | X86_CR4_UMIP |
-					     X86_CR4_FSGSBASE | X86_CR4_CET | X86_CR4_FRED;
+					     X86_CR4_FSGSBASE | X86_CR4_CET | X86_CR4_FRED |
+					     X86_CR4_LASS;
 static DEFINE_STATIC_KEY_FALSE_RO(cr_pinning);
 static unsigned long cr4_pinned_bits __ro_after_init;
 
-- 
2.43.0