nvme: fix handling of EINVAL on pci_alloc_irq_vectors_affinity()

At least on SPARC, if MSI/MSI-X isn't supported, we get EINVAL if
we ask for more than one vector. This isn't covered by our ENOSPC
check.

If we get EINVAL, decrease our ask to just one vector, instead of
bailing out in error.

Fixes: 3b6592f7 ("nvme: utilize two queue maps, one for reads and one for writes")
Reported-by: Guenter Roeck <linux@roeck-us.net>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/nvme/host/pci.c

@@ -2088,15 +2088,11 @@ static int nvme_setup_irqs(struct nvme_dev *dev, int nr_io_queues)
 			affd.nr_sets = 1;
 
 		/*
-		 * Need IRQs for read+write queues, and one for the admin queue.
-		 * If we can't get more than one vector, we have to share the
-		 * admin queue and IO queue vector. For that case, don't add
-		 * an extra vector for the admin queue, or we'll continue
-		 * asking for 2 and get -ENOSPC in return.
+		 * If we got a failure and we're down to asking for just
+		 * 1 + 1 queues, just ask for a single vector. We'll share
+		 * that between the single IO queue and the admin queue.
 		 */
-		if (result == -ENOSPC && nr_io_queues == 1)
-			nr_io_queues = 1;
-		else
+		if (!(result < 0 && nr_io_queues == 1))
 			nr_io_queues = irq_sets[0] + irq_sets[1] + 1;
 
 		result = pci_alloc_irq_vectors_affinity(pdev, nr_io_queues,
@@ -2104,13 +2100,19 @@ static int nvme_setup_irqs(struct nvme_dev *dev, int nr_io_queues)
 				PCI_IRQ_ALL_TYPES | PCI_IRQ_AFFINITY, &affd);
 
 		/*
-		 * Need to reduce our vec counts
+		 * Need to reduce our vec counts. If we get ENOSPC, the
+		 * platform should support mulitple vecs, we just need
+		 * to decrease our ask. If we get EINVAL, the platform
+		 * likely does not. Back down to ask for just one vector.
 		 */
 		if (result == -ENOSPC) {
 			nr_io_queues--;
 			if (!nr_io_queues)
 				return result;
 			continue;
+		} else if (result == -EINVAL) {
+			nr_io_queues = 1;
+			continue;
 		} else if (result <= 0)
 			return -EIO;
 		break;