This is a note to let you know that I've just added the patch titled
x86/bugs: Fix handling when SRSO mitigation is disabled
to the 6.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-bugs-fix-handling-when-srso-mitigation-is-disabl.patch
and it can be found in the queue-6.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 986dc2c2467899b7682044ebe7521334f2f4cede
Author: David Kaplan <david.kaplan@xxxxxxx>
Date: Wed Sep 4 10:07:11 2024 -0500
x86/bugs: Fix handling when SRSO mitigation is disabled
[ Upstream commit 1dbb6b1495d472806fef1f4c94f5b3e4c89a3c1d ]
When the SRSO mitigation is disabled, either via mitigations=off or
spec_rstack_overflow=off, the warning about the lack of IBPB-enhancing
microcode is printed anyway.
This is unnecessary since the user has turned off the mitigation.
[ bp: Massage, drop SBPB rationale as it doesn't matter because when
mitigations are disabled x86_pred_cmd is not being used anyway. ]
Signed-off-by: David Kaplan <david.kaplan@xxxxxxx>
Signed-off-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Acked-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20240904150711.193022-1-david.kaplan@xxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index b6f927f6c567e..47c84503ad9be 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -2545,10 +2545,9 @@ static void __init srso_select_mitigation(void)
{
bool has_microcode = boot_cpu_has(X86_FEATURE_IBPB_BRTYPE);
- if (cpu_mitigations_off())
- return;
-
- if (!boot_cpu_has_bug(X86_BUG_SRSO)) {
+ if (!boot_cpu_has_bug(X86_BUG_SRSO) ||
+ cpu_mitigations_off() ||
+ srso_cmd == SRSO_CMD_OFF) {
if (boot_cpu_has(X86_FEATURE_SBPB))
x86_pred_cmd = PRED_CMD_SBPB;
return;
@@ -2579,11 +2578,6 @@ static void __init srso_select_mitigation(void)
}
switch (srso_cmd) {
- case SRSO_CMD_OFF:
- if (boot_cpu_has(X86_FEATURE_SBPB))
- x86_pred_cmd = PRED_CMD_SBPB;
- return;
-
case SRSO_CMD_MICROCODE:
if (has_microcode) {
srso_mitigation = SRSO_MITIGATION_MICROCODE;
@@ -2637,6 +2631,8 @@ static void __init srso_select_mitigation(void)
pr_err("WARNING: kernel not compiled with MITIGATION_SRSO.\n");
}
break;
+ default:
+ break;
}
out:
