powerpc/eeh: Add eeh_force_recover to debugfs

This patch adds a debugfs interface to force scheduling a recovery event.
This can be used to recover a specific PE or schedule a "special" recovery
even that checks for errors at the PHB level.
To force a recovery of a normal PE, use:

 echo '<#pe>:<#phb>' > /sys/kernel/debug/powerpc/eeh_force_recover

To force a scan for broken PHBs:

 echo 'hwcheck' > /sys/kernel/debug/powerpc/eeh_force_recover

Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/include/asm/eeh_event.h

@@ -33,6 +33,7 @@ struct eeh_event {
 
 int eeh_event_init(void);
 int eeh_send_failure_event(struct eeh_pe *pe);
+int __eeh_send_failure_event(struct eeh_pe *pe);
 void eeh_remove_event(struct eeh_pe *pe, bool force);
 void eeh_handle_normal_event(struct eeh_pe *pe);
 void eeh_handle_special_event(void);

arch/powerpc/kernel/eeh.c

@@ -1838,6 +1838,62 @@ static int eeh_enable_dbgfs_get(void *data, u64 *val)
 
 DEFINE_DEBUGFS_ATTRIBUTE(eeh_enable_dbgfs_ops, eeh_enable_dbgfs_get,
 			 eeh_enable_dbgfs_set, "0x%llx\n");
+
+static ssize_t eeh_force_recover_write(struct file *filp,
+				const char __user *user_buf,
+				size_t count, loff_t *ppos)
+{
+	struct pci_controller *hose;
+	uint32_t phbid, pe_no;
+	struct eeh_pe *pe;
+	char buf[20];
+	int ret;
+
+	ret = simple_write_to_buffer(buf, sizeof(buf), ppos, user_buf, count);
+	if (!ret)
+		return -EFAULT;
+
+	/*
+	 * When PE is NULL the event is a "special" event. Rather than
+	 * recovering a specific PE it forces the EEH core to scan for failed
+	 * PHBs and recovers each. This needs to be done before any device
+	 * recoveries can occur.
+	 */
+	if (!strncmp(buf, "hwcheck", 7)) {
+		__eeh_send_failure_event(NULL);
+		return count;
+	}
+
+	ret = sscanf(buf, "%x:%x", &phbid, &pe_no);
+	if (ret != 2)
+		return -EINVAL;
+
+	hose = pci_find_controller_for_domain(phbid);
+	if (!hose)
+		return -ENODEV;
+
+	/* Retrieve PE */
+	pe = eeh_pe_get(hose, pe_no, 0);
+	if (!pe)
+		return -ENODEV;
+
+	/*
+	 * We don't do any state checking here since the detection
+	 * process is async to the recovery process. The recovery
+	 * thread *should* not break even if we schedule a recovery
+	 * from an odd state (e.g. PE removed, or recovery of a
+	 * non-isolated PE)
+	 */
+	__eeh_send_failure_event(pe);
+
+	return ret < 0 ? ret : count;
+}
+
+static const struct file_operations eeh_force_recover_fops = {
+	.open	= simple_open,
+	.llseek	= no_llseek,
+	.write	= eeh_force_recover_write,
+};
 #endif
 
 static int __init eeh_init_proc(void)
@@ -1853,6 +1909,9 @@ static int __init eeh_init_proc(void)
 		debugfs_create_bool("eeh_disable_recovery", 0600,
 				powerpc_debugfs_root,
 				&eeh_debugfs_no_recover);
+		debugfs_create_file_unsafe("eeh_force_recover", 0600,
+				powerpc_debugfs_root, NULL,
+				&eeh_force_recover_fops);
 		eeh_cache_debugfs_init();
 #endif
 	}

arch/powerpc/kernel/eeh_event.c

@@ -121,20 +121,11 @@ int eeh_event_init(void)
  * the actual event will be delivered in a normal context
  * (from a workqueue).
  */
-int eeh_send_failure_event(struct eeh_pe *pe)
+int __eeh_send_failure_event(struct eeh_pe *pe)
 {
 	unsigned long flags;
 	struct eeh_event *event;
 
-	/*
-	 * If we've manually supressed recovery events via debugfs
-	 * then just drop it on the floor.
-	 */
-	if (eeh_debugfs_no_recover) {
-		pr_err("EEH: Event dropped due to no_recover setting\n");
-		return 0;
-	}
-
 	event = kzalloc(sizeof(*event), GFP_ATOMIC);
 	if (!event) {
 		pr_err("EEH: out of memory, event not handled\n");
@@ -153,6 +144,20 @@ int eeh_send_failure_event(struct eeh_pe *pe)
 	return 0;
 }
 
+int eeh_send_failure_event(struct eeh_pe *pe)
+{
+	/*
+	 * If we've manually supressed recovery events via debugfs
+	 * then just drop it on the floor.
+	 */
+	if (eeh_debugfs_no_recover) {
+		pr_err("EEH: Event dropped due to no_recover setting\n");
+		return 0;
+	}
+
+	return __eeh_send_failure_event(pe);
+}
+
 /**
  * eeh_remove_event - Remove EEH event from the queue
  * @pe: Event binding to the PE