NVMe: Add MSI support

Some devices only have support for MSI, not MSI-X.  While MSI is more
limited, it still provides better performance than line-based interrupts.

Signed-off-by: Ramachandra Gajula <rama@fastorsystems.com>
Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>

1 files changed, 32 insertions, 8 deletions

diff --git a/drivers/block/nvme-core.c b/drivers/block/nvme-core.c
index a57d3bcec803..ce79a590b45b 100644
--- a/drivers/block/nvme-core.c
+++ b/drivers/block/nvme-core.c
@@ -1637,7 +1637,8 @@ static int set_queue_count(struct nvme_dev *dev, int count)
 
 static int nvme_setup_io_queues(struct nvme_dev *dev)
 {
-        int result, cpu, i, nr_io_queues, db_bar_size, q_depth;
+        struct pci_dev *pdev = dev->pci_dev;
+        int result, cpu, i, nr_io_queues, db_bar_size, q_depth, q_count;
 
         nr_io_queues = num_online_cpus();
         result = set_queue_count(dev, nr_io_queues);
@@ -1646,14 +1647,14 @@ static int nvme_setup_io_queues(struct nvme_dev *dev)
         if (result < nr_io_queues)
                 nr_io_queues = result;
 
+        q_count = nr_io_queues;
         /* Deregister the admin queue's interrupt */
         free_irq(dev->entry[0].vector, dev->queues[0]);
 
         db_bar_size = 4096 + ((nr_io_queues + 1) << (dev->db_stride + 3));
         if (db_bar_size > 8192) {
                 iounmap(dev->bar);
-                dev->bar = ioremap(pci_resource_start(dev->pci_dev, 0),
-                                                                db_bar_size);
+                dev->bar = ioremap(pci_resource_start(pdev, 0), db_bar_size);
                 dev->dbs = ((void __iomem *)dev->bar) + 4096;
                 dev->queues[0]->q_db = dev->dbs;
         }
@@ -1661,19 +1662,36 @@ static int nvme_setup_io_queues(struct nvme_dev *dev)
         for (i = 0; i < nr_io_queues; i++)
                 dev->entry[i].entry = i;
         for (;;) {
-                result = pci_enable_msix(dev->pci_dev, dev->entry,
-                                                                nr_io_queues);
+                result = pci_enable_msix(pdev, dev->entry, nr_io_queues);
                 if (result == 0) {
                         break;
                 } else if (result > 0) {
                         nr_io_queues = result;
                         continue;
                 } else {
-                        nr_io_queues = 1;
+                        nr_io_queues = 0;
                         break;
                 }
         }
 
+        if (nr_io_queues == 0) {
+                nr_io_queues = q_count;
+                for (;;) {
+                        result = pci_enable_msi_block(pdev, nr_io_queues);
+                        if (result == 0) {
+                                for (i = 0; i < nr_io_queues; i++)
+                                        dev->entry[i].vector = i + pdev->irq;
+                                break;
+                        } else if (result > 0) {
+                                nr_io_queues = result;
+                                continue;
+                        } else {
+                                nr_io_queues = 1;
+                                break;
+                        }
+                }
+        }
+
         result = queue_request_irq(dev, dev->queues[0], "nvme admin");
         /* XXX: handle failure here */
 
@@ -1854,7 +1872,10 @@ static void nvme_free_dev(struct kref *kref)
 {
         struct nvme_dev *dev = container_of(kref, struct nvme_dev, kref);
         nvme_dev_remove(dev);
-        pci_disable_msix(dev->pci_dev);
+        if (dev->pci_dev->msi_enabled)
+                pci_disable_msi(dev->pci_dev);
+        else if (dev->pci_dev->msix_enabled)
+                pci_disable_msix(dev->pci_dev);
         iounmap(dev->bar);
         nvme_release_instance(dev);
         nvme_release_prp_pools(dev);
@@ -1987,7 +2008,10 @@ static int nvme_probe(struct pci_dev *pdev, const struct pci_device_id *id)
  unmap:
         iounmap(dev->bar);
  disable_msix:
-        pci_disable_msix(pdev);
+        if (dev->pci_dev->msi_enabled)
+                pci_disable_msi(dev->pci_dev);
+        else if (dev->pci_dev->msix_enabled)
+                pci_disable_msix(dev->pci_dev);
         nvme_release_instance(dev);
         nvme_release_prp_pools(dev);
  disable: