[PATCH v10 04/15] x86/cpu: Set LASS CR4 bit as pinning sensitive

Sohil Mehta
2025-10-07T06:54:00Z

From: Yian Chen <yian.chen@intel.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@intel.com>
Signed-off-by: Sohil Mehta <sohil.mehta@intel.com>
---
v10:
- No change.
---
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 c7d3512914ca..61ab332eaf73 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;

--
2.43.0