virtio_pci: optional MSI-X support
This implements optional MSI-X support in virtio_pci. MSI-X is used whenever the host supports at least 2 MSI-X vectors: 1 for configuration changes and 1 for virtqueues. Per-virtqueue vectors are allocated if enough vectors available. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Acked-by: Anthony Liguori <aliguori@us.ibm.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (+ whitespace, style)
This commit is contained in:
Michael S. Tsirkin
Rusty Russell
parent
77cf524654
commit
82af8ce84e
2 changed files with 218 additions and 20 deletions
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@ -42,6 +42,26 @@ struct virtio_pci_device
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/* a list of queues so we can dispatch IRQs */
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spinlock_t lock;
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struct list_head virtqueues;
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/* MSI-X support */
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int msix_enabled;
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int intx_enabled;
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struct msix_entry *msix_entries;
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/* Name strings for interrupts. This size should be enough,
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* and I'm too lazy to allocate each name separately. */
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char (*msix_names)[256];
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/* Number of available vectors */
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unsigned msix_vectors;
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/* Vectors allocated */
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unsigned msix_used_vectors;
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};
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/* Constants for MSI-X */
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/* Use first vector for configuration changes, second and the rest for
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* virtqueues Thus, we need at least 2 vectors for MSI. */
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enum {
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VP_MSIX_CONFIG_VECTOR = 0,
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VP_MSIX_VQ_VECTOR = 1,
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};
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struct virtio_pci_vq_info
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@ -60,6 +80,9 @@ struct virtio_pci_vq_info
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/* the list node for the virtqueues list */
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struct list_head node;
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/* MSI-X vector (or none) */
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unsigned vector;
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};
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/* Qumranet donated their vendor ID for devices 0x1000 thru 0x10FF. */
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@ -109,7 +132,8 @@ static void vp_get(struct virtio_device *vdev, unsigned offset,
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void *buf, unsigned len)
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{
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struct virtio_pci_device *vp_dev = to_vp_device(vdev);
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void __iomem *ioaddr = vp_dev->ioaddr + VIRTIO_PCI_CONFIG + offset;
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void __iomem *ioaddr = vp_dev->ioaddr +
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VIRTIO_PCI_CONFIG(vp_dev) + offset;
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u8 *ptr = buf;
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int i;
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@ -123,7 +147,8 @@ static void vp_set(struct virtio_device *vdev, unsigned offset,
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const void *buf, unsigned len)
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{
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struct virtio_pci_device *vp_dev = to_vp_device(vdev);
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void __iomem *ioaddr = vp_dev->ioaddr + VIRTIO_PCI_CONFIG + offset;
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void __iomem *ioaddr = vp_dev->ioaddr +
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VIRTIO_PCI_CONFIG(vp_dev) + offset;
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const u8 *ptr = buf;
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int i;
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@ -221,7 +246,122 @@ static irqreturn_t vp_interrupt(int irq, void *opaque)
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return vp_vring_interrupt(irq, opaque);
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}
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/* the config->find_vq() implementation */
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static void vp_free_vectors(struct virtio_device *vdev)
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{
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struct virtio_pci_device *vp_dev = to_vp_device(vdev);
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int i;
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if (vp_dev->intx_enabled) {
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free_irq(vp_dev->pci_dev->irq, vp_dev);
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vp_dev->intx_enabled = 0;
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}
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for (i = 0; i < vp_dev->msix_used_vectors; ++i)
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free_irq(vp_dev->msix_entries[i].vector, vp_dev);
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vp_dev->msix_used_vectors = 0;
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if (vp_dev->msix_enabled) {
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/* Disable the vector used for configuration */
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iowrite16(VIRTIO_MSI_NO_VECTOR,
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vp_dev->ioaddr + VIRTIO_MSI_CONFIG_VECTOR);
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/* Flush the write out to device */
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ioread16(vp_dev->ioaddr + VIRTIO_MSI_CONFIG_VECTOR);
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vp_dev->msix_enabled = 0;
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pci_disable_msix(vp_dev->pci_dev);
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}
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}
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static int vp_enable_msix(struct pci_dev *dev, struct msix_entry *entries,
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int *options, int noptions)
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{
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int i;
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for (i = 0; i < noptions; ++i)
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if (!pci_enable_msix(dev, entries, options[i]))
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return options[i];
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return -EBUSY;
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}
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static int vp_request_vectors(struct virtio_device *vdev, unsigned max_vqs)
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{
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struct virtio_pci_device *vp_dev = to_vp_device(vdev);
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const char *name = dev_name(&vp_dev->vdev.dev);
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unsigned i, v;
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int err = -ENOMEM;
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/* We want at most one vector per queue and one for config changes.
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* Fallback to separate vectors for config and a shared for queues.
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* Finally fall back to regular interrupts. */
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int options[] = { max_vqs + 1, 2 };
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int nvectors = max(options[0], options[1]);
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vp_dev->msix_entries = kmalloc(nvectors * sizeof *vp_dev->msix_entries,
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GFP_KERNEL);
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if (!vp_dev->msix_entries)
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goto error_entries;
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vp_dev->msix_names = kmalloc(nvectors * sizeof *vp_dev->msix_names,
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GFP_KERNEL);
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if (!vp_dev->msix_names)
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goto error_names;
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for (i = 0; i < nvectors; ++i)
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vp_dev->msix_entries[i].entry = i;
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err = vp_enable_msix(vp_dev->pci_dev, vp_dev->msix_entries,
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options, ARRAY_SIZE(options));
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if (err < 0) {
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/* Can't allocate enough MSI-X vectors, use regular interrupt */
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vp_dev->msix_vectors = 0;
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err = request_irq(vp_dev->pci_dev->irq, vp_interrupt,
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IRQF_SHARED, name, vp_dev);
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if (err)
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goto error_irq;
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vp_dev->intx_enabled = 1;
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} else {
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vp_dev->msix_vectors = err;
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vp_dev->msix_enabled = 1;
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/* Set the vector used for configuration */
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v = vp_dev->msix_used_vectors;
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snprintf(vp_dev->msix_names[v], sizeof *vp_dev->msix_names,
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"%s-config", name);
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err = request_irq(vp_dev->msix_entries[v].vector,
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vp_config_changed, 0, vp_dev->msix_names[v],
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vp_dev);
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if (err)
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goto error_irq;
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++vp_dev->msix_used_vectors;
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iowrite16(v, vp_dev->ioaddr + VIRTIO_MSI_CONFIG_VECTOR);
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/* Verify we had enough resources to assign the vector */
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v = ioread16(vp_dev->ioaddr + VIRTIO_MSI_CONFIG_VECTOR);
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if (v == VIRTIO_MSI_NO_VECTOR) {
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err = -EBUSY;
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goto error_irq;
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}
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}
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if (vp_dev->msix_vectors && vp_dev->msix_vectors != max_vqs + 1) {
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/* Shared vector for all VQs */
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v = vp_dev->msix_used_vectors;
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snprintf(vp_dev->msix_names[v], sizeof *vp_dev->msix_names,
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"%s-virtqueues", name);
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err = request_irq(vp_dev->msix_entries[v].vector,
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vp_vring_interrupt, 0, vp_dev->msix_names[v],
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vp_dev);
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if (err)
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goto error_irq;
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++vp_dev->msix_used_vectors;
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}
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return 0;
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error_irq:
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vp_free_vectors(vdev);
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kfree(vp_dev->msix_names);
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error_names:
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kfree(vp_dev->msix_entries);
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error_entries:
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return err;
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}
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static struct virtqueue *vp_find_vq(struct virtio_device *vdev, unsigned index,
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void (*callback)(struct virtqueue *vq),
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const char *name)
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@ -230,7 +370,7 @@ static struct virtqueue *vp_find_vq(struct virtio_device *vdev, unsigned index,
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struct virtio_pci_vq_info *info;
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struct virtqueue *vq;
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unsigned long flags, size;
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u16 num;
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u16 num, vector;
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int err;
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/* Select the queue we're interested in */
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@ -249,6 +389,7 @@ static struct virtqueue *vp_find_vq(struct virtio_device *vdev, unsigned index,
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info->queue_index = index;
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info->num = num;
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info->vector = VIRTIO_MSI_NO_VECTOR;
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size = PAGE_ALIGN(vring_size(num, VIRTIO_PCI_VRING_ALIGN));
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info->queue = alloc_pages_exact(size, GFP_KERNEL|__GFP_ZERO);
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@ -272,12 +413,43 @@ static struct virtqueue *vp_find_vq(struct virtio_device *vdev, unsigned index,
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vq->priv = info;
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info->vq = vq;
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/* allocate per-vq vector if available and necessary */
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if (callback && vp_dev->msix_used_vectors < vp_dev->msix_vectors) {
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vector = vp_dev->msix_used_vectors;
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snprintf(vp_dev->msix_names[vector], sizeof *vp_dev->msix_names,
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"%s-%s", dev_name(&vp_dev->vdev.dev), name);
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err = request_irq(vp_dev->msix_entries[vector].vector,
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vring_interrupt, 0,
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vp_dev->msix_names[vector], vq);
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if (err)
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goto out_request_irq;
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info->vector = vector;
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++vp_dev->msix_used_vectors;
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} else
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vector = VP_MSIX_VQ_VECTOR;
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if (callback && vp_dev->msix_enabled) {
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iowrite16(vector, vp_dev->ioaddr + VIRTIO_MSI_QUEUE_VECTOR);
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vector = ioread16(vp_dev->ioaddr + VIRTIO_MSI_QUEUE_VECTOR);
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if (vector == VIRTIO_MSI_NO_VECTOR) {
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err = -EBUSY;
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goto out_assign;
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}
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}
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spin_lock_irqsave(&vp_dev->lock, flags);
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list_add(&info->node, &vp_dev->virtqueues);
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spin_unlock_irqrestore(&vp_dev->lock, flags);
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return vq;
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out_assign:
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if (info->vector != VIRTIO_MSI_NO_VECTOR) {
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free_irq(vp_dev->msix_entries[info->vector].vector, vq);
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--vp_dev->msix_used_vectors;
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}
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out_request_irq:
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vring_del_virtqueue(vq);
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out_activate_queue:
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iowrite32(0, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN);
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free_pages_exact(info->queue, size);
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@ -286,17 +458,27 @@ static struct virtqueue *vp_find_vq(struct virtio_device *vdev, unsigned index,
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return ERR_PTR(err);
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}
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/* the config->del_vq() implementation */
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static void vp_del_vq(struct virtqueue *vq)
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{
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struct virtio_pci_device *vp_dev = to_vp_device(vq->vdev);
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struct virtio_pci_vq_info *info = vq->priv;
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unsigned long size;
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iowrite16(info->queue_index, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_SEL);
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if (info->vector != VIRTIO_MSI_NO_VECTOR)
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free_irq(vp_dev->msix_entries[info->vector].vector, vq);
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if (vp_dev->msix_enabled) {
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iowrite16(VIRTIO_MSI_NO_VECTOR,
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vp_dev->ioaddr + VIRTIO_MSI_QUEUE_VECTOR);
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/* Flush the write out to device */
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ioread8(vp_dev->ioaddr + VIRTIO_PCI_ISR);
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}
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vring_del_virtqueue(vq);
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/* Select and deactivate the queue */
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iowrite16(info->queue_index, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_SEL);
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iowrite32(0, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN);
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size = PAGE_ALIGN(vring_size(info->num, VIRTIO_PCI_VRING_ALIGN));
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@ -304,30 +486,46 @@ static void vp_del_vq(struct virtqueue *vq)
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kfree(info);
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}
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/* the config->del_vqs() implementation */
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static void vp_del_vqs(struct virtio_device *vdev)
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{
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struct virtqueue *vq, *n;
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list_for_each_entry_safe(vq, n, &vdev->vqs, list)
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vp_del_vq(vq);
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vp_free_vectors(vdev);
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}
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/* the config->find_vqs() implementation */
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static int vp_find_vqs(struct virtio_device *vdev, unsigned nvqs,
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struct virtqueue *vqs[],
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vq_callback_t *callbacks[],
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const char *names[])
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{
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int i;
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int vectors = 0;
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int i, err;
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/* How many vectors would we like? */
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for (i = 0; i < nvqs; ++i)
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if (callbacks[i])
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++vectors;
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err = vp_request_vectors(vdev, vectors);
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if (err)
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goto error_request;
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for (i = 0; i < nvqs; ++i) {
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vqs[i] = vp_find_vq(vdev, i, callbacks[i], names[i]);
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if (IS_ERR(vqs[i]))
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goto error;
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goto error_find;
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}
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return 0;
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error:
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error_find:
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vp_del_vqs(vdev);
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error_request:
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return PTR_ERR(vqs[i]);
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}
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@ -349,7 +547,7 @@ static void virtio_pci_release_dev(struct device *_d)
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struct virtio_pci_device *vp_dev = to_vp_device(dev);
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struct pci_dev *pci_dev = vp_dev->pci_dev;
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free_irq(pci_dev->irq, vp_dev);
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vp_del_vqs(dev);
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pci_set_drvdata(pci_dev, NULL);
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pci_iounmap(pci_dev, vp_dev->ioaddr);
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pci_release_regions(pci_dev);
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@ -408,21 +606,13 @@ static int __devinit virtio_pci_probe(struct pci_dev *pci_dev,
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vp_dev->vdev.id.vendor = pci_dev->subsystem_vendor;
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vp_dev->vdev.id.device = pci_dev->subsystem_device;
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/* register a handler for the queue with the PCI device's interrupt */
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err = request_irq(vp_dev->pci_dev->irq, vp_interrupt, IRQF_SHARED,
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dev_name(&vp_dev->vdev.dev), vp_dev);
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if (err)
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goto out_set_drvdata;
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/* finally register the virtio device */
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err = register_virtio_device(&vp_dev->vdev);
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if (err)
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goto out_req_irq;
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goto out_set_drvdata;
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return 0;
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out_req_irq:
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free_irq(pci_dev->irq, vp_dev);
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out_set_drvdata:
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pci_set_drvdata(pci_dev, NULL);
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pci_iounmap(pci_dev, vp_dev->ioaddr);
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@ -47,9 +47,17 @@
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/* The bit of the ISR which indicates a device configuration change. */
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#define VIRTIO_PCI_ISR_CONFIG 0x2
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/* MSI-X registers: only enabled if MSI-X is enabled. */
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/* A 16-bit vector for configuration changes. */
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#define VIRTIO_MSI_CONFIG_VECTOR 20
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/* A 16-bit vector for selected queue notifications. */
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#define VIRTIO_MSI_QUEUE_VECTOR 22
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/* Vector value used to disable MSI for queue */
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#define VIRTIO_MSI_NO_VECTOR 0xffff
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/* The remaining space is defined by each driver as the per-driver
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* configuration space */
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#define VIRTIO_PCI_CONFIG 20
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#define VIRTIO_PCI_CONFIG(dev) ((dev)->msix_enabled ? 24 : 20)
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/* Virtio ABI version, this must match exactly */
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#define VIRTIO_PCI_ABI_VERSION 0
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