This is a note to let you know that I've just added the patch titled
x86/CPU/AMD: WARN when setting EFER.AUTOIBRS if and only if the WRMSR fails
to the 6.6-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-cpu-amd-warn-when-setting-efer.autoibrs-if-and-o.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 3d30b30f731b3d19bbc80129460575e7bdd7ff3a
Author: Sean Christopherson <seanjc@xxxxxxxxxx>
Date: Fri Dec 6 08:20:06 2024 -0800
x86/CPU/AMD: WARN when setting EFER.AUTOIBRS if and only if the WRMSR fails
[ Upstream commit 492077668fb453b8b16c842fcf3fafc2ebc190e9 ]
When ensuring EFER.AUTOIBRS is set, WARN only on a negative return code
from msr_set_bit(), as '1' is used to indicate the WRMSR was successful
('0' indicates the MSR bit was already set).
Fixes: 8cc68c9c9e92 ("x86/CPU/AMD: Make sure EFER[AIBRSE] is set")
Reported-by: Nathan Chancellor <nathan@xxxxxxxxxx>
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Link: https://lore.kernel.org/r/Z1MkNofJjt7Oq0G6@xxxxxxxxxx
Closes: https://lore.kernel.org/all/20241205220604.GA2054199@thelio-3990X
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 145c81c68394b..9413fb767c6a7 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -1205,7 +1205,7 @@ static void init_amd(struct cpuinfo_x86 *c)
*/
if (spectre_v2_in_eibrs_mode(spectre_v2_enabled) &&
cpu_has(c, X86_FEATURE_AUTOIBRS))
- WARN_ON_ONCE(msr_set_bit(MSR_EFER, _EFER_AUTOIBRS));
+ WARN_ON_ONCE(msr_set_bit(MSR_EFER, _EFER_AUTOIBRS) < 0);
if (!cpu_has(c, X86_FEATURE_HYPERVISOR) &&
cpu_has_amd_erratum(c, amd_erratum_1485))
