ena: Reinit netmap adapter struct upon sysctl changes

When attaching ENA driver, ena_netmap_attach() is invoked which, in turn
calls netmap_attach which, initializes a struct netmap_adapter,
allocating the struct's netmap_ring and the struct selinfo.

When we change the interface number of queues we need to reinit the
netmap adapter struct as well, so we need to detach it in order to free
the memory allocated by netmap_attach and allocate new memory based on
the new parameters like number of rings, ring size etc...

Without detaching and attaching the netmap interface, if we're to change
the number of queues from 8 to 2 for example and try to enable netmap,
the kernel will panic since the original netmap struct within the
kernel's possession still thinks that the driver has 8 queues which will
eventually cause a non-allocated virtual address access fault.

Approved by: cperciva (mentor)
MFC after: 2 weeks
Sponsored by: Amazon, Inc.

1 files changed, 50 insertions, 1 deletions

diff --git a/sys/dev/ena/ena.c b/sys/dev/ena/ena.c
index bbc857004671..bfde950cb2b1 100644
--- a/sys/dev/ena/ena.c
+++ b/sys/dev/ena/ena.c
@@ -171,7 +171,9 @@ static int ena_copy_customer_metrics(struct ena_adapter *);
 static void ena_timer_service(void *);
 static enum ena_regs_reset_reason_types check_cdesc_in_tx_cq(struct ena_adapter *,
     struct ena_ring *);
-
+#ifdef DEV_NETMAP
+static int ena_reinit_netmap(struct ena_adapter *adapter);
+#endif
 
 static char ena_version[] = ENA_DEVICE_NAME ENA_DRV_MODULE_NAME
     " v" ENA_DRV_MODULE_VERSION;
@@ -1162,6 +1164,21 @@ ena_refill_rx_bufs(struct ena_ring *rx_ring, uint32_t num)
 	return (i);
 }
 
+#ifdef DEV_NETMAP
+static int
+ena_reinit_netmap(struct ena_adapter *adapter)
+{
+	int rc;
+
+	netmap_detach(adapter->ifp);
+	rc = ena_netmap_attach(adapter);
+	if (rc != 0)
+		ena_log(adapter->pdev, ERR, "netmap attach failed: %d\n", rc);
+
+	return rc;
+}
+
+#endif /* DEV_NETMAP */
 int
 ena_update_buf_ring_size(struct ena_adapter *adapter,
     uint32_t new_buf_ring_size)
@@ -1179,6 +1196,12 @@ ena_update_buf_ring_size(struct ena_adapter *adapter,
 	/* Reconfigure buf ring for all Tx rings. */
 	ena_free_all_io_rings_resources(adapter);
 	ena_init_io_rings_advanced(adapter);
+#ifdef DEV_NETMAP
+	rc = ena_reinit_netmap(adapter);
+	if (rc != 0)
+		return rc;
+
+#endif /* DEV_NETMAP */
 	if (dev_was_up) {
 		/*
 		 * If ena_up() fails, it's not because of recent buf_ring size
@@ -1196,7 +1219,12 @@ ena_update_buf_ring_size(struct ena_adapter *adapter,
 			adapter->buf_ring_size = old_buf_ring_size;
 			ena_free_all_io_rings_resources(adapter);
 			ena_init_io_rings_advanced(adapter);
+#ifdef DEV_NETMAP
+			rc = ena_reinit_netmap(adapter);
+			if (rc != 0)
+				return rc;
 
+#endif /* DEV_NETMAP */
 			ENA_FLAG_SET_ATOMIC(ENA_FLAG_DEV_UP_BEFORE_RESET,
 			    adapter);
 			ena_trigger_reset(adapter, ENA_REGS_RESET_OS_TRIGGER);
@@ -1224,6 +1252,12 @@ ena_update_queue_size(struct ena_adapter *adapter, uint32_t new_tx_size,
 
 	/* Configure queues with new size. */
 	ena_init_io_rings_basic(adapter);
+#ifdef DEV_NETMAP
+	rc = ena_reinit_netmap(adapter);
+	if (rc != 0)
+		return rc;
+
+#endif /* DEV_NETMAP */
 	if (dev_was_up) {
 		rc = ena_up(adapter);
 		if (unlikely(rc != 0)) {
@@ -1235,7 +1269,12 @@ ena_update_queue_size(struct ena_adapter *adapter, uint32_t new_tx_size,
 			adapter->requested_tx_ring_size = old_tx_size;
 			adapter->requested_rx_ring_size = old_rx_size;
 			ena_init_io_rings_basic(adapter);
+#ifdef DEV_NETMAP
+			rc = ena_reinit_netmap(adapter);
+			if (rc != 0)
+				return rc;
 
+#endif /* DEV_NETMAP */
 			/* And try again. */
 			rc = ena_up(adapter);
 			if (unlikely(rc != 0)) {
@@ -1359,7 +1398,12 @@ ena_update_io_queue_nb(struct ena_adapter *adapter, uint32_t new_num)
 	ena_down(adapter);
 
 	ena_update_io_rings(adapter, new_num);
+#ifdef DEV_NETMAP
+	rc = ena_reinit_netmap(adapter);
+	if (rc != 0)
+		return rc;
 
+#endif /* DEV_NETMAP */
 	if (dev_was_up) {
 		rc = ena_up(adapter);
 		if (unlikely(rc != 0)) {
@@ -1369,7 +1413,12 @@ ena_update_io_queue_nb(struct ena_adapter *adapter, uint32_t new_num)
 			    new_num, old_num);
 
 			ena_update_io_rings(adapter, old_num);
+#ifdef DEV_NETMAP
+			rc = ena_reinit_netmap(adapter);
+			if (rc != 0)
+				return rc;
 
+#endif /* DEV_NETMAP */
 			rc = ena_up(adapter);
 			if (unlikely(rc != 0)) {
 				ena_log(adapter->pdev, ERR,