This is a note to let you know that I've just added the patch titled
x86/cpu: Add Lunar Lake to list of CPUs with a broken MONITOR implementation
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-add-lunar-lake-to-list-of-cpus-with-a-broken.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 bf904cc805fac95a390aeac49d2965907662b208
Author: Len Brown <len.brown@xxxxxxxxx>
Date: Tue Nov 12 21:07:00 2024 -0500
x86/cpu: Add Lunar Lake to list of CPUs with a broken MONITOR implementation
[ Upstream commit c9a4b55431e5220347881e148725bed69c84e037 ]
Under some conditions, MONITOR wakeups on Lunar Lake processors
can be lost, resulting in significant user-visible delays.
Add Lunar Lake to X86_BUG_MONITOR so that wake_up_idle_cpu()
always sends an IPI, avoiding this potential delay.
Reported originally here:
https://bugzilla.kernel.org/show_bug.cgi?id=219364
[ dhansen: tweak subject ]
Signed-off-by: Len Brown <len.brown@xxxxxxxxx>
Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Cc:stable@xxxxxxxxxxxxxxx
Link: https://lore.kernel.org/all/a4aa8842a3c3bfdb7fe9807710eef159cbf0e705.1731463305.git.len.brown%40intel.com
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index 78f34ff32c9b..97259485c111 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -666,7 +666,9 @@ static void init_intel(struct cpuinfo_x86 *c)
c->x86_vfm == INTEL_WESTMERE_EX))
set_cpu_bug(c, X86_BUG_CLFLUSH_MONITOR);
- if (boot_cpu_has(X86_FEATURE_MWAIT) && c->x86_vfm == INTEL_ATOM_GOLDMONT)
+ if (boot_cpu_has(X86_FEATURE_MWAIT) &&
+ (c->x86_vfm == INTEL_ATOM_GOLDMONT ||
+ c->x86_vfm == INTEL_LUNARLAKE_M))
set_cpu_bug(c, X86_BUG_MONITOR);
#ifdef CONFIG_X86_64
