NVMe: Add pci suspend/resume driver callbacks

Used for going in and out of low power states. Resuming reuses the IO
queues from the previous initialization, freeing any allocated queues
that are no longer usable.
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>

drivers/block/nvme-core.c

@@ -789,6 +789,12 @@ static void nvme_make_request(struct request_queue *q, struct bio *bio)
 	struct nvme_queue *nvmeq = get_nvmeq(ns->dev);
 	int result = -EBUSY;
 
+	if (!nvmeq) {
+		put_nvmeq(NULL);
+		bio_endio(bio, -EIO);
+		return;
+	}
+
 	spin_lock_irq(&nvmeq->q_lock);
 	if (!nvmeq->q_suspended && bio_list_empty(&nvmeq->sq_cong))
 		result = nvme_submit_bio_queue(nvmeq, ns, bio);
@@ -1256,9 +1262,13 @@ static int nvme_configure_admin_queue(struct nvme_dev *dev)
 	if (result < 0)
 		return result;
 
-	nvmeq = nvme_alloc_queue(dev, 0, 64, 0);
-	if (!nvmeq)
-		return -ENOMEM;
+	nvmeq = dev->queues[0];
+	if (!nvmeq) {
+		nvmeq = nvme_alloc_queue(dev, 0, 64, 0);
+		if (!nvmeq)
+			return -ENOMEM;
+		dev->queues[0] = nvmeq;
+	}
 
 	aqa = nvmeq->q_depth - 1;
 	aqa |= aqa << 16;
@@ -1275,21 +1285,16 @@ static int nvme_configure_admin_queue(struct nvme_dev *dev)
 
 	result = nvme_enable_ctrl(dev, cap);
 	if (result)
-		goto free_q;
+		return result;
 
 	result = queue_request_irq(dev, nvmeq, "nvme admin");
 	if (result)
-		goto free_q;
+		return result;
 
-	dev->queues[0] = nvmeq;
 	spin_lock(&nvmeq->q_lock);
 	nvme_init_queue(nvmeq, 0);
 	spin_unlock(&nvmeq->q_lock);
 	return result;
-
- free_q:
-	nvme_free_queue(nvmeq);
-	return result;
 }
 
 struct nvme_iod *nvme_map_user_pages(struct nvme_dev *dev, int write,
@@ -1797,6 +1802,21 @@ static int nvme_setup_io_queues(struct nvme_dev *dev)
 	if (result)
 		goto free_queues;
 
+	/* Free previously allocated queues that are no longer usable */
+	spin_lock(&dev_list_lock);
+	for (i = dev->queue_count - 1; i > nr_io_queues; i--) {
+		struct nvme_queue *nvmeq = dev->queues[i];
+
+		spin_lock(&nvmeq->q_lock);
+		nvme_cancel_ios(nvmeq, false);
+		spin_unlock(&nvmeq->q_lock);
+
+		nvme_free_queue(nvmeq);
+		dev->queue_count--;
+		dev->queues[i] = NULL;
+	}
+	spin_unlock(&dev_list_lock);
+
 	cpu = cpumask_first(cpu_online_mask);
 	for (i = 0; i < nr_io_queues; i++) {
 		irq_set_affinity_hint(dev->entry[i].vector, get_cpu_mask(cpu));
@@ -1805,7 +1825,7 @@ static int nvme_setup_io_queues(struct nvme_dev *dev)
 
 	q_depth = min_t(int, NVME_CAP_MQES(readq(&dev->bar->cap)) + 1,
 								NVME_Q_DEPTH);
-	for (i = 0; i < nr_io_queues; i++) {
+	for (i = dev->queue_count - 1; i < nr_io_queues; i++) {
 		dev->queues[i + 1] = nvme_alloc_queue(dev, i + 1, q_depth, i);
 		if (!dev->queues[i + 1]) {
 			result = -ENOMEM;
@@ -2191,8 +2211,30 @@ static void nvme_remove(struct pci_dev *pdev)
 #define nvme_link_reset NULL
 #define nvme_slot_reset NULL
 #define nvme_error_resume NULL
-#define nvme_suspend NULL
-#define nvme_resume NULL
+
+static int nvme_suspend(struct device *dev)
+{
+	struct pci_dev *pdev = to_pci_dev(dev);
+	struct nvme_dev *ndev = pci_get_drvdata(pdev);
+
+	nvme_dev_shutdown(ndev);
+	return 0;
+}
+
+static int nvme_resume(struct device *dev)
+{
+	struct pci_dev *pdev = to_pci_dev(dev);
+	struct nvme_dev *ndev = pci_get_drvdata(pdev);
+	int ret;
+
+	ret = nvme_dev_start(ndev);
+	/* XXX: should remove gendisks if resume fails */
+	if (ret)
+		nvme_free_queues(ndev);
+	return ret;
+}
+
+static SIMPLE_DEV_PM_OPS(nvme_dev_pm_ops, nvme_suspend, nvme_resume);
 
 static const struct pci_error_handlers nvme_err_handler = {
 	.error_detected	= nvme_error_detected,
@@ -2216,8 +2258,9 @@ static struct pci_driver nvme_driver = {
 	.id_table	= nvme_id_table,
 	.probe		= nvme_probe,
 	.remove		= nvme_remove,
-	.suspend	= nvme_suspend,
-	.resume		= nvme_resume,
+	.driver		= {
+		.pm	= &nvme_dev_pm_ops,
+	},
 	.err_handler	= &nvme_err_handler,
 };