x86/mce/AMD: Reset Threshold Limit after logging error

The error count field in MCA_MISC does not get reset by hardware when the
threshold has been reached. Software is expected to reset it. Currently,
the threshold limit only gets reset during init or when a user writes to
sysfs.

If the user is not monitoring threshold interrupts and resetting
the limit then the user will only see 1 interrupt when the limit is first
hit. So if, for example, the limit is set to 10 then only 1 interrupt will
be recorded after 10 errors even if 100 errors have occurred. The user may
then assume that only 10 errors have occurred.

Signed-off-by: Yazen Ghannam <Yazen.Ghannam@amd.com>
Cc: Aravind Gopalakrishnan <aravindksg.lkml@gmail.com>
Cc: linux-edac <linux-edac@vger.kernel.org>
Cc: x86-ml <x86@kernel.org>
Link: http://lkml.kernel.org/r/1479244433-69267-1-git-send-email-Yazen.Ghannam@amd.com
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

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

@@ -665,6 +665,7 @@ static void amd_threshold_interrupt(void)
 {
 	u32 low = 0, high = 0, address = 0;
 	unsigned int bank, block, cpu = smp_processor_id();
+	struct thresh_restart tr;
 
 	/* assume first bank caused it */
 	for (bank = 0; bank < mca_cfg.banks; ++bank) {
@@ -701,6 +702,11 @@ static void amd_threshold_interrupt(void)
 
 log:
 	__log_error(bank, false, true, ((u64)high << 32) | low);
+
+	/* Reset threshold block after logging error. */
+	memset(&tr, 0, sizeof(tr));
+	tr.b = &per_cpu(threshold_banks, cpu)[bank]->blocks[block];
+	threshold_restart_bank(&tr);
 }
 
 /*