x86, MCE, AMD: Drop software-defined bank in error thresholding

Aravind had the good question about why we're assigning a
software-defined bank when reporting error thresholding errors instead
of simply using the bank which reports the last error causing the
overflow.

Digging through git history, it pointed to

95268664390b ("[PATCH] x86_64: mce_amd support for family 0x10 processors")

which added that functionality. The problem with this, however, is that
tools don't know about software-defined banks and get puzzled. So drop
that K8_MCE_THRESHOLD_BASE and simply use the hw bank reporting the
thresholding interrupt.

Save us a couple of MSR reads while at it.

Reported-by: Aravind Gopalakrishnan <aravind.gopalakrishnan@amd.com>
Link: https://lkml.kernel.org/r/5435B206.60402@amd.com
Signed-off-by: Borislav Petkov <bp@suse.de>

arch/x86/include/asm/mce.h

@@ -78,7 +78,6 @@
 /* Software defined banks */
 #define MCE_EXTENDED_BANK	128
 #define MCE_THERMAL_BANK	(MCE_EXTENDED_BANK + 0)
-#define K8_MCE_THRESHOLD_BASE   (MCE_EXTENDED_BANK + 1)
 
 #define MCE_LOG_LEN 32
 #define MCE_LOG_SIGNATURE	"MACHINECHECK"

arch/x86/kernel/cpu/mcheck/mce_amd.c

@@ -318,10 +318,9 @@ static void amd_threshold_interrupt(void)
 
 log:
 	mce_setup(&m);
-	rdmsrl(MSR_IA32_MCG_STATUS, m.mcgstatus);
-	rdmsrl(address, m.misc);
 	rdmsrl(MSR_IA32_MCx_STATUS(bank), m.status);
-	m.bank = K8_MCE_THRESHOLD_BASE + bank * NR_BLOCKS + block;
+	m.misc = ((u64)high << 32) | low;
+	m.bank = bank;
 	mce_log(&m);
 
 	wrmsrl(MSR_IA32_MCx_STATUS(bank), 0);