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

JIRA: https://issues.redhat.com/browse/RHEL-113399

commit 30ad231
Author: JP Kobryn <inwardvessel@gmail.com>
Date:   Fri Jun 27 10:49:35 2025 -0700

    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

Signed-off-by: Steve Best <sbest@redhat.com>

Author: sfbest

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)