x86/mce: Use severity table to handle uncorrected errors in kernel

mce_severity_intel() has a special case to promote UC and AR errors
in kernel context to PANIC severity.

The "AR" case is already handled with separate entries in the severity
table for all instruction fetch errors, and those data fetch errors that
are not in a recoverable area of the kernel (i.e. have an extable fixup
entry).

Add an entry to the severity table for UC errors in kernel context that
reports severity = PANIC. Delete the special case code from
mce_severity_intel().

Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220922195136.54575-2-tony.luck@intel.com

Author: aegl

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

@@ -202,6 +202,11 @@ static struct severity {
 		PANIC, "Overflowed uncorrected",
 		BITSET(MCI_STATUS_OVER|MCI_STATUS_UC)
 		),
+	MCESEV(
+		PANIC, "Uncorrected in kernel",
+		BITSET(MCI_STATUS_UC),
+		KERNEL
+		),
 	MCESEV(
 		UC, "Uncorrected",
 		BITSET(MCI_STATUS_UC)
@@ -391,9 +396,6 @@ static noinstr int mce_severity_intel(struct mce *m, struct pt_regs *regs, char
 			*msg = s->msg;
 		s->covered = 1;
 
-		if (s->sev >= MCE_UC_SEVERITY && ctx == IN_KERNEL)
-			return MCE_PANIC_SEVERITY;
-
 		return s->sev;
 	}
 }