The following commit has been merged into the x86/urgent branch of tip:

Commit-ID: c9a4b55431e5220347881e148725bed69c84e037 Gitweb: https://git.kernel.org/tip/c9a4b55431e5220347881e148725bed69c84e037 Author: Len Brown len.brown@intel.com AuthorDate: Tue, 12 Nov 2024 21:07:00 -05:00 Committer: Dave Hansen dave.hansen@linux.intel.com CommitterDate: Wed, 04 Dec 2024 12:30:14 -08:00

x86/cpu: Add Lunar Lake to list of CPUs with a broken MONITOR implementation

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@intel.com Signed-off-by: Dave Hansen dave.hansen@linux.intel.com Reviewed-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Cc:stable@vger.kernel.org Link: https://lore.kernel.org/all/a4aa8842a3c3bfdb7fe9807710eef159cbf0e705.1731463... --- arch/x86/kernel/cpu/intel.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c index d1de300..8ded9f8 100644 --- a/arch/x86/kernel/cpu/intel.c +++ b/arch/x86/kernel/cpu/intel.c @@ -555,7 +555,9 @@ 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