From: JP Kobryn <inwardvessel@gmail.com>
Date: Fri, 27 Jun 2025 17:49:35 +0000 (-0700)
Subject: x86/mce: Make sure CMCI banks are cleared during shutdown on Intel
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=30ad231a5029bfa16e46ce868497b1a5cdd3c24d;p=linux-2.6-block.git

x86/mce: Make sure CMCI banks are cleared during shutdown on Intel

CMCI banks are not cleared during shutdown on Intel CPUs. As a side effect,
when a kexec is performed, CPUs coming back online are unable to
rediscover/claim these occupied banks which breaks MCE reporting.

Clear the CPU ownership during shutdown via cmci_clear() so the banks can
be reclaimed and MCE reporting will become functional once more.

  [ bp: Massage commit message. ]

Reported-by: Aijay Adams <aijay@meta.com>
Signed-off-by: JP Kobryn <inwardvessel@gmail.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
Cc: <stable@kernel.org>
Link: https://lore.kernel.org/20250627174935.95194-1-inwardvessel@gmail.com
---

diff --git a/arch/x86/kernel/cpu/mce/intel.c b/arch/x86/kernel/cpu/mce/intel.c
index efcf21e9552e..9b149b9c4109 100644
--- a/arch/x86/kernel/cpu/mce/intel.c
+++ b/arch/x86/kernel/cpu/mce/intel.c
@@ -478,6 +478,7 @@ void mce_intel_feature_init(struct cpuinfo_x86 *c)
 void mce_intel_feature_clear(struct cpuinfo_x86 *c)
 {
 	intel_clear_lmce();
+	cmci_clear();
 }
 
 bool intel_filter_mce(struct mce *m)