[PATCH v2 3/3] x86/cpu: Remove LASS restriction on EFI

Sohil Mehta posted 3 patches 2 weeks, 5 days ago
[PATCH v2 3/3] x86/cpu: Remove LASS restriction on EFI
Posted by Sohil Mehta 2 weeks, 5 days ago
The initial LASS enabling has been deferred to much later during boot,
and EFI runtime services now run with LASS temporarily disabled. This
removes LASS from the path of all EFI services.

Remove the LASS restriction on EFI config, as the two can now coexist.

Signed-off-by: Sohil Mehta <sohil.mehta@intel.com>
---
v2:
 - No change
---
 arch/x86/kernel/cpu/common.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index cefd0722e6cc..5833849f0b52 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -415,14 +415,9 @@ static __always_inline void setup_lass(struct cpuinfo_x86 *c)
 	 * Legacy vsyscall page access causes a #GP when LASS is active.
 	 * Disable LASS because the #GP handler doesn't support vsyscall
 	 * emulation.
-	 *
-	 * Also disable LASS when running under EFI, as some runtime and
-	 * boot services rely on 1:1 mappings in the lower half.
 	 */
-	if (IS_ENABLED(CONFIG_X86_VSYSCALL_EMULATION) ||
-	    IS_ENABLED(CONFIG_EFI)) {
+	if (IS_ENABLED(CONFIG_X86_VSYSCALL_EMULATION))
 		setup_clear_cpu_cap(X86_FEATURE_LASS);
-	}
 }
 
 static int enable_lass(unsigned int cpu)
-- 
2.43.0