From 68400c1aaf02636a97c45ba198110b66feb270a9 Mon Sep 17 00:00:00 2001 From: Sohil Mehta Date: Tue, 20 Jan 2026 15:47:30 -0800 Subject: [PATCH] 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 Signed-off-by: Dave Hansen Tested-by: Tony Luck Tested-by: Maciej Wieczor-Retman Link: https://patch.msgid.link/20260120234730.2215498-4-sohil.mehta@intel.com --- 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 8c56d5970d61..3557f0e6b3aa 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)