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

commit 30ad231 upstream.

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
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: inwardvessel

arch/x86/kernel/cpu/mce/intel.c

@@ -500,6 +500,7 @@ 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)