x86, mce, severity: Extend the the mce_severity mechanism to handle UCNA/DEFERRED error

Until now, the mce_severity mechanism can only identify the severity
of UCNA error as MCE_KEEP_SEVERITY. Meanwhile, it is not able to filter
out DEFERRED error for AMD platform.

This patch extends the mce_severity mechanism for handling
UCNA/DEFERRED error. In order to do this, the patch introduces a new
severity level - MCE_UCNA/DEFERRED_SEVERITY.

In addition, mce_severity is specific to machine check exception,
and it will check MCIP/EIPV/RIPV bits. In order to use mce_severity
mechanism in non-exception context, the patch also introduces a new
argument (is_excp) for mce_severity. `is_excp' is used to explicitly
specify the calling context of mce_severity.

Reviewed-by: Aravind Gopalakrishnan <[e-mail]>
Signed-off-by: Chen Yucong <[e-mail]>
Signed-off-by: Tony Luck <[e-mail]>

arch/x86/include/asm/mce.h

···
 #define MCI_STATUS_S	 (1ULL<<56)  /* Signaled machine check */
 #define MCI_STATUS_AR	 (1ULL<<55)  /* Action required */
 
+/* AMD-specific bits */
+#define MCI_STATUS_DEFERRED	(1ULL<<44)  /* declare an uncorrected error */
+#define MCI_STATUS_POISON	(1ULL<<43)  /* access poisonous data */
+
 /*
  * Note that the full MCACOD field of IA32_MCi_STATUS MSR is
  * bits 15:0.  But bit 12 is the 'F' bit, defined for corrected

arch/x86/kernel/cpu/mcheck/mce-internal.h

···
 
 enum severity_level {
 	MCE_NO_SEVERITY,
+	MCE_DEFERRED_SEVERITY,
+	MCE_UCNA_SEVERITY = MCE_DEFERRED_SEVERITY,
 	MCE_KEEP_SEVERITY,
 	MCE_SOME_SEVERITY,
 	MCE_AO_SEVERITY,
···
 	char			attrname[ATTR_LEN];	/* attribute name */
 };
 
-int mce_severity(struct mce *a, int tolerant, char **msg);
+int mce_severity(struct mce *a, int tolerant, char **msg, bool is_excp);
 struct dentry *mce_get_debugfs_dir(void);
 
 extern struct mce_bank *mce_banks;

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

···
 
 enum context { IN_KERNEL = 1, IN_USER = 2 };
 enum ser { SER_REQUIRED = 1, NO_SER = 2 };
+enum exception { EXCP_CONTEXT = 1, NO_EXCP = 2 };
 
 static struct severity {
 	u64 mask;
···
 	unsigned char mcgres;
 	unsigned char ser;
 	unsigned char context;
+	unsigned char excp;
 	unsigned char covered;
 	char *msg;
 } severities[] = {
···
 #define  USER		.context = IN_USER
 #define  SER		.ser = SER_REQUIRED
 #define  NOSER		.ser = NO_SER
+#define  EXCP		.excp = EXCP_CONTEXT
+#define  NOEXCP		.excp = NO_EXCP
 #define  BITCLR(x)	.mask = x, .result = 0
 #define  BITSET(x)	.mask = x, .result = x
 #define  MCGMASK(x, y)	.mcgmask = x, .mcgres = y
···
 		),
 	MCESEV(
 		NO, "Not enabled",
-		BITCLR(MCI_STATUS_EN)
+		EXCP, BITCLR(MCI_STATUS_EN)
 		),
 	MCESEV(
 		PANIC, "Processor context corrupt",
···
 	/* When MCIP is not set something is very confused */
 	MCESEV(
 		PANIC, "MCIP not set in MCA handler",
-		MCGMASK(MCG_STATUS_MCIP, 0)
+		EXCP, MCGMASK(MCG_STATUS_MCIP, 0)
 		),
 	/* Neither return not error IP -- no chance to recover -> PANIC */
 	MCESEV(
 		PANIC, "Neither restart nor error IP",
-		MCGMASK(MCG_STATUS_RIPV|MCG_STATUS_EIPV, 0)
+		EXCP, MCGMASK(MCG_STATUS_RIPV|MCG_STATUS_EIPV, 0)
 		),
 	MCESEV(
 		PANIC, "In kernel and no restart IP",
-		KERNEL, MCGMASK(MCG_STATUS_RIPV, 0)
+		EXCP, KERNEL, MCGMASK(MCG_STATUS_RIPV, 0)
+		),
+	MCESEV(
+		DEFERRED, "Deferred error",
+		NOSER, MASK(MCI_STATUS_UC|MCI_STATUS_DEFERRED|MCI_STATUS_POISON, MCI_STATUS_DEFERRED)
 		),
 	MCESEV(
 		KEEP, "Corrected error",
···
 
 	/* ignore OVER for UCNA */
 	MCESEV(
-		KEEP, "Uncorrected no action required",
+		UCNA, "Uncorrected no action required",
 		SER, MASK(MCI_UC_SAR, MCI_STATUS_UC)
 		),
 	MCESEV(
···
 	return ((m->cs & 3) == 3) ? IN_USER : IN_KERNEL;
 }
 
-int mce_severity(struct mce *m, int tolerant, char **msg)
+int mce_severity(struct mce *m, int tolerant, char **msg, bool is_excp)
 {
+	enum exception excp = (is_excp ? EXCP_CONTEXT : NO_EXCP);
 	enum context ctx = error_context(m);
 	struct severity *s;
 
···
 		if (s->ser == NO_SER && mca_cfg.ser)
 			continue;
 		if (s->context && ctx != s->context)
+			continue;
+		if (s->excp && excp != s->excp)
 			continue;
 		if (msg)
 			*msg = s->msg;

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

···
 			if (quirk_no_way_out)
 				quirk_no_way_out(i, m, regs);
 		}
-		if (mce_severity(m, mca_cfg.tolerant, msg) >= MCE_PANIC_SEVERITY)
+		if (mce_severity(m, mca_cfg.tolerant, msg, true) >=
+		    MCE_PANIC_SEVERITY)
 			ret = 1;
 	}
 	return ret;
···
 	for_each_possible_cpu(cpu) {
 		int severity = mce_severity(&per_cpu(mces_seen, cpu),
 					    mca_cfg.tolerant,
-					    &nmsg);
+					    &nmsg, true);
 		if (severity > global_worst) {
 			msg = nmsg;
 			global_worst = severity;
···
 		 */
 		add_taint(TAINT_MACHINE_CHECK, LOCKDEP_NOW_UNRELIABLE);
 
-		severity = mce_severity(&m, cfg->tolerant, NULL);
+		severity = mce_severity(&m, cfg->tolerant, NULL, true);
 
 		/*
-		 * When machine check was for corrected handler don't touch,
-		 * unless we're panicing.
+		 * When machine check was for corrected/deferred handler don't
+		 * touch, unless we're panicing.
 		 */
-		if (severity == MCE_KEEP_SEVERITY && !no_way_out)
+		if ((severity == MCE_KEEP_SEVERITY ||
+		     severity == MCE_UCNA_SEVERITY) && !no_way_out)
 			continue;
 		__set_bit(i, toclear);
 		if (severity == MCE_NO_SEVERITY) {

drivers/edac/mce_amd.h

···
 #define R4(x)				(((x) >> 4) & 0xf)
 #define R4_MSG(x)			((R4(x) < 9) ?  rrrr_msgs[R4(x)] : "Wrong R4!")
 
-#define MCI_STATUS_DEFERRED		BIT_64(44)
-#define MCI_STATUS_POISON		BIT_64(43)
-
 extern const char * const pp_msgs[];
 
 enum tt_ids {