Commit fc9fd3f9 authored by Josh Poimboeuf's avatar Josh Poimboeuf Committed by Ingo Molnar
Browse files

x86/bugs: Use SBPB in write_ibpb() if applicable 



write_ibpb() does IBPB, which (among other things) flushes branch type
predictions on AMD.  If the CPU has SRSO_NO, or if the SRSO mitigation
has been disabled, branch type flushing isn't needed, in which case the
lighter-weight SBPB can be used.

The 'x86_pred_cmd' variable already keeps track of whether IBPB or SBPB
should be used.  Use that instead of hardcoding IBPB.

Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/17c5dcd14b29199b75199d67ff7758de9d9a4928.1744148254.git.jpoimboe@kernel.org
parent 13235d6d

arch/x86/entry/entry.S

+1 −1
Original line number Diff line number Diff line
@@ -21,7 +21,7 @@ 
SYM_FUNC_START(write_ibpb)

	ANNOTATE_NOENDBR

	movl	$MSR_IA32_PRED_CMD, %ecx

	movl	$PRED_CMD_IBPB, %eax

	movl	_ASM_RIP(x86_pred_cmd), %eax

	xorl	%edx, %edx

	wrmsr