x86/mce: Fix possibly incorrect severity calculation on AMD

The function mce_severity_amd_smca() requires m->bank to be initialized
for correct operation. Fix the one case, where mce_severity() is called
without doing so.

Fixes: 6bda529e ("x86/mce: Grade uncorrected errors for SMCA-enabled systems")
Fixes: d28af26f ("x86/MCE: Initialize mce.bank in the case of a fatal error in mce_no_way_out()")
Signed-off-by: NJan H. Schönherr <jschoenh@amazon.de>
Signed-off-by: NBorislav Petkov <bp@suse.de>
Reviewed-by: NTony Luck <tony.luck@intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: linux-edac <linux-edac@vger.kernel.org>
Cc: <stable@vger.kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86-ml <x86@kernel.org>
Cc: Yazen Ghannam <Yazen.Ghannam@amd.com>
Link: https://lkml.kernel.org/r/20191210000733.17979-4-jschoenh@amazon.de

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

@@ -819,8 +819,8 @@ static int mce_no_way_out(struct mce *m, char **msg, unsigned long *validp,
 		if (quirk_no_way_out)
 			quirk_no_way_out(i, m, regs);
 
+		m->bank = i;
 		if (mce_severity(m, mca_cfg.tolerant, &tmp, true) >= MCE_PANIC_SEVERITY) {
-			m->bank = i;
 			mce_read_aux(m, i);
 			*msg = tmp;
 			return 1;