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>

diff --git a/drivers/block/nvme-core.c b/drivers/block/nvme-core.c
index a57d3bcec80316176dcc3b60a78d0b8d07b18f0b..ce79a590b45bff7c9c9e3e5ed206f1d7342c1a55 100644 (file)
--- 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: