x86/cpu: Remove LASS restriction on EFI

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>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Tested-by: Tony Luck <tony.luck@intel.com>
Tested-by: Maciej Wieczor-Retman <maciej.wieczor-retman@intel.com>
Link: https://patch.msgid.link/20260120234730.2215498-4-sohil.mehta@intel.com

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 8c56d5970d616dddf45a99c5b79a515d2d7fd685..3557f0e6b3aa5cda738fafc368352bec2d2b0648 100644 (file)
--- 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)