linux-kernel - [PATCH v2 11/12] x86/cpu: Set LASS CR4 bit as pinning sensitive

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Message-Id: <20230530114247.21821-12-alexander.shishkin@linux.intel.com>
Date:   Tue, 30 May 2023 14:42:46 +0300
From:   Alexander Shishkin <alexander.shishkin@...ux.intel.com>
To:     linux-kernel@...r.kernel.org, x86@...nel.org,
        Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Ravi Shankar <ravi.v.shankar@...el.com>,
        Tony Luck <tony.luck@...el.com>,
        Sohil Mehta <sohil.mehta@...el.com>,
        Paul Lai <paul.c.lai@...el.com>
Cc:     Yian Chen <yian.chen@...el.com>
Subject: [PATCH v2 11/12] 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>
Reviewed-by: Tony Luck <tony.luck@...el.com>
---
 arch/x86/kernel/cpu/common.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index f26c56fe9963..9ddc19c8832d 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -422,7 +422,7 @@ 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_FSGSBASE | X86_CR4_CET | X86_CR4_LASS;
 static DEFINE_STATIC_KEY_FALSE_RO(cr_pinning);
 static unsigned long cr4_pinned_bits __ro_after_init;
 
-- 
2.39.2