From: Sohil Mehta Date: Tue, 20 Jan 2026 23:47:30 +0000 (-0800) Subject: x86/cpu: Remove LASS restriction on EFI X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=68400c1aaf02636a97c45ba198110b66feb270a9;p=thirdparty%2Flinux.git 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 --- diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 8c56d5970d616..3557f0e6b3aa5 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)