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Message-Id: <20250414132729.679254-23-sashal@kernel.org>
Date: Mon, 14 Apr 2025 09:27:17 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
stable@...r.kernel.org
Cc: Josh Poimboeuf <jpoimboe@...nel.org>,
Ingo Molnar <mingo@...nel.org>,
Sasha Levin <sashal@...nel.org>,
luto@...nel.org,
tglx@...utronix.de,
mingo@...hat.com,
bp@...en8.de,
dave.hansen@...ux.intel.com,
x86@...nel.org
Subject: [PATCH AUTOSEL 6.13 23/34] x86/bugs: Use SBPB in write_ibpb() if applicable
From: Josh Poimboeuf <jpoimboe@...nel.org>
[ Upstream commit fc9fd3f98423367c79e0bd85a9515df26dc1b3cc ]
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: Josh Poimboeuf <jpoimboe@...nel.org>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Link: https://lore.kernel.org/r/17c5dcd14b29199b75199d67ff7758de9d9a4928.1744148254.git.jpoimboe@kernel.org
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
arch/x86/entry/entry.S | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/entry/entry.S b/arch/x86/entry/entry.S
index b7ea3e8e9eccd..58e3124ee2b42 100644
--- a/arch/x86/entry/entry.S
+++ b/arch/x86/entry/entry.S
@@ -18,7 +18,7 @@
SYM_FUNC_START(entry_ibpb)
movl $MSR_IA32_PRED_CMD, %ecx
- movl $PRED_CMD_IBPB, %eax
+ movl _ASM_RIP(x86_pred_cmd), %eax
xorl %edx, %edx
wrmsr
--
2.39.5
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