s390/pci: handle stale deconfiguration events

The PCIs event with PEC 0x0303 or 0x0304 are a request to deconfigure
a PCI function, respectively an indication that it was already
deconfigured by the platform. If such an event is queued during boot it
may happen that the platform has already adjusted the configuration flag
of the relevant function in the CLP List PCI Functions result. In this
case we might not have configured the PCI function at all and should
thus ignore the event. Note that no locking is necessary as event
handling only starts after we have fully initialized the zPCI subsystem
and scanned all PCI devices listed in the CLP result.

Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Acked-by: Pierre Morel <pmorel@linux.ibm.com>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

1 files changed, 18 insertions, 8 deletions

diff --git a/arch/s390/pci/pci_event.c b/arch/s390/pci/pci_event.c
index 8ecc256d27a5..cd447b96b4b1 100644
--- a/arch/s390/pci/pci_event.c
+++ b/arch/s390/pci/pci_event.c
@@ -76,8 +76,6 @@ void zpci_event_error(void *data)
 
 static void zpci_event_hard_deconfigured(struct zpci_dev *zdev, u32 fh)
 {
-	enum zpci_state state;
-
 	zdev->fh = fh;
 	/* Give the driver a hint that the function is
 	 * already unusable.
@@ -88,15 +86,12 @@ static void zpci_event_hard_deconfigured(struct zpci_dev *zdev, u32 fh)
 	 */
 	zpci_disable_device(zdev);
 	zdev->state = ZPCI_FN_STATE_STANDBY;
-	if (!clp_get_state(zdev->fid, &state) &&
-	    state == ZPCI_FN_STATE_RESERVED) {
-		zpci_zdev_put(zdev);
-	}
 }
 
 static void __zpci_event_availability(struct zpci_ccdf_avail *ccdf)
 {
 	struct zpci_dev *zdev = get_zdev_by_fid(ccdf->fid);
+	enum zpci_state state;
 
 	zpci_err("avail CCDF:\n");
 	zpci_err_hex(ccdf, sizeof(*ccdf));
@@ -123,13 +118,28 @@ static void __zpci_event_availability(struct zpci_ccdf_avail *ccdf)
 		break;
 	case 0x0303: /* Deconfiguration requested */
 		if (zdev) {
+			/* The event may have been queued before we confirgured
+			 * the device.
+			 */
+			if (zdev->state != ZPCI_FN_STATE_CONFIGURED)
+				break;
 			zdev->fh = ccdf->fh;
 			zpci_deconfigure_device(zdev);
 		}
 		break;
 	case 0x0304: /* Configured -> Standby|Reserved */
-		if (zdev)
-			zpci_event_hard_deconfigured(zdev, ccdf->fh);
+		if (zdev) {
+			/* The event may have been queued before we confirgured
+			 * the device.:
+			 */
+			if (zdev->state == ZPCI_FN_STATE_CONFIGURED)
+				zpci_event_hard_deconfigured(zdev, ccdf->fh);
+			/* The 0x0304 event may immediately reserve the device */
+			if (!clp_get_state(zdev->fid, &state) &&
+			    state == ZPCI_FN_STATE_RESERVED) {
+				zpci_zdev_put(zdev);
+			}
+		}
 		break;
 	case 0x0306: /* 0x308 or 0x302 for multiple devices */
 		zpci_remove_reserved_devices();