[PATCHv6 11/16] x86/cpu: Set LASS CR4 bit as pinning sensitive
From: Kirill A. Shutemov
Date: Fri Jun 20 2025 - 09:56:18 EST
From: Yian Chen <yian.chen@xxxxxxxxx>
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@xxxxxxxxx>
Signed-off-by: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Reviewed-by: Tony Luck <tony.luck@xxxxxxxxx>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---
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 1a779e302872..d12ce36a76f5 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -403,7 +403,8 @@ static __always_inline void setup_umip(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;
--
2.47.2