Commit 68400c1a authored by Sohil Mehta's avatar Sohil Mehta Committed by Dave Hansen
Browse files

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: default avatarSohil Mehta <sohil.mehta@intel.com>
Signed-off-by: default avatarDave Hansen <dave.hansen@linux.intel.com>
Tested-by: default avatarTony Luck <tony.luck@intel.com>
Tested-by: default avatarMaciej Wieczor-Retman <maciej.wieczor-retman@intel.com>
Link: https://patch.msgid.link/20260120234730.2215498-4-sohil.mehta@intel.com
parent 0021e71c

arch/x86/kernel/cpu/common.c

+1 −6
Original line number Diff line number Diff line
@@ -415,15 +415,10 @@ 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)

{