x86/gsseg: Use the LKGS instruction if available for load_gs_index()

Browse source

The LKGS instruction atomically loads a segment descriptor into the
%gs descriptor registers, *except* that %gs.base is unchanged, and the
base is instead loaded into MSR_IA32_KERNEL_GS_BASE, which is exactly
what we want this function to do.

Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>
Signed-off-by: Xin Li <xin3.li@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230112072032.35626-6-xin3.li@intel.com
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>

...

This commit is contained in:

H. Peter Anvin (Intel) 2023-01-11 23:20:32 -08:00 • committed by Ingo Molnar

parent ae53fa1870

commit 92cbbadf73

3 changed files with 31 additions and 4 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

33

arch/x86/include/asm/gsseg.h

View file

1

arch/x86/kernel/cpu/common.c

View file

1

arch/x86/xen/enlighten_pv.c

View file