Merge branch 'dmaengine' into async-tx-next

Conflicts:
	crypto/async_tx/async_xor.c
	drivers/dma/ioat/dma_v2.h
	drivers/dma/ioat/pci.c
	drivers/md/raid5.c

4 files changed, 396 insertions, 69 deletions

diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
index 018c070a357f..3a43ebf83a49 100644
--- a/drivers/virtio/virtio.c
+++ b/drivers/virtio/virtio.c
@@ -31,21 +31,37 @@ static ssize_t modalias_show(struct device *_d,
         return sprintf(buf, "virtio:d%08Xv%08X\n",
                        dev->id.device, dev->id.vendor);
 }
+static ssize_t features_show(struct device *_d,
+                             struct device_attribute *attr, char *buf)
+{
+        struct virtio_device *dev = container_of(_d, struct virtio_device, dev);
+        unsigned int i;
+        ssize_t len = 0;
+
+        /* We actually represent this as a bitstring, as it could be
+         * arbitrary length in future. */
+        for (i = 0; i < ARRAY_SIZE(dev->features)*BITS_PER_LONG; i++)
+                len += sprintf(buf+len, "%c",
+                               test_bit(i, dev->features) ? '1' : '0');
+        len += sprintf(buf+len, "\n");
+        return len;
+}
 static struct device_attribute virtio_dev_attrs[] = {
         __ATTR_RO(device),
         __ATTR_RO(vendor),
         __ATTR_RO(status),
         __ATTR_RO(modalias),
+        __ATTR_RO(features),
         __ATTR_NULL
 };
 
 static inline int virtio_id_match(const struct virtio_device *dev,
                                   const struct virtio_device_id *id)
 {
-        if (id->device != dev->id.device)
+        if (id->device != dev->id.device && id->device != VIRTIO_DEV_ANY_ID)
                 return 0;
 
-        return id->vendor == VIRTIO_DEV_ANY_ID || id->vendor != dev->id.vendor;
+        return id->vendor == VIRTIO_DEV_ANY_ID || id->vendor == dev->id.vendor;
 }
 
 /* This looks through all the IDs a driver claims to support.  If any of them
@@ -118,13 +134,14 @@ static int virtio_dev_probe(struct device *_d)
                 if (device_features & (1 << i))
                         set_bit(i, dev->features);
 
+        dev->config->finalize_features(dev);
+
         err = drv->probe(dev);
         if (err)
                 add_status(dev, VIRTIO_CONFIG_S_FAILED);
-        else {
-                dev->config->finalize_features(dev);
+        else
                 add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
-        }
+
         return err;
 }
 
@@ -185,6 +202,8 @@ int register_virtio_device(struct virtio_device *dev)
         /* Acknowledge that we've seen the device. */
         add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 
+        INIT_LIST_HEAD(&dev->vqs);
+
         /* device_register() causes the bus infrastructure to look for a
          * matching driver. */
         err = device_register(&dev->dev);
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 9c76a061a04d..26b278264796 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -204,6 +204,9 @@ static int balloon(void *_vballoon)
 static int virtballoon_probe(struct virtio_device *vdev)
 {
         struct virtio_balloon *vb;
+        struct virtqueue *vqs[2];
+        vq_callback_t *callbacks[] = { balloon_ack, balloon_ack };
+        const char *names[] = { "inflate", "deflate" };
         int err;
 
         vdev->priv = vb = kmalloc(sizeof(*vb), GFP_KERNEL);
@@ -218,22 +221,17 @@ static int virtballoon_probe(struct virtio_device *vdev)
         vb->vdev = vdev;
 
         /* We expect two virtqueues. */
-        vb->inflate_vq = vdev->config->find_vq(vdev, 0, balloon_ack);
-        if (IS_ERR(vb->inflate_vq)) {
-                err = PTR_ERR(vb->inflate_vq);
+        err = vdev->config->find_vqs(vdev, 2, vqs, callbacks, names);
+        if (err)
                 goto out_free_vb;
-        }
 
-        vb->deflate_vq = vdev->config->find_vq(vdev, 1, balloon_ack);
-        if (IS_ERR(vb->deflate_vq)) {
-                err = PTR_ERR(vb->deflate_vq);
-                goto out_del_inflate_vq;
-        }
+        vb->inflate_vq = vqs[0];
+        vb->deflate_vq = vqs[1];
 
         vb->thread = kthread_run(balloon, vb, "vballoon");
         if (IS_ERR(vb->thread)) {
                 err = PTR_ERR(vb->thread);
-                goto out_del_deflate_vq;
+                goto out_del_vqs;
         }
 
         vb->tell_host_first
@@ -241,10 +239,8 @@ static int virtballoon_probe(struct virtio_device *vdev)
 
         return 0;
 
-out_del_deflate_vq:
-        vdev->config->del_vq(vb->deflate_vq);
-out_del_inflate_vq:
-        vdev->config->del_vq(vb->inflate_vq);
+out_del_vqs:
+        vdev->config->del_vqs(vdev);
 out_free_vb:
         kfree(vb);
 out:
@@ -264,8 +260,7 @@ static void virtballoon_remove(struct virtio_device *vdev)
         /* Now we reset the device so we can clean up the queues. */
         vdev->config->reset(vdev);
 
-        vdev->config->del_vq(vb->deflate_vq);
-        vdev->config->del_vq(vb->inflate_vq);
+        vdev->config->del_vqs(vdev);
         kfree(vb);
 }
 
diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
index 330aacbdec1f..193c8f0e5cc5 100644
--- a/drivers/virtio/virtio_pci.c
+++ b/drivers/virtio/virtio_pci.c
@@ -42,6 +42,26 @@ struct virtio_pci_device
         /* a list of queues so we can dispatch IRQs */
         spinlock_t lock;
         struct list_head virtqueues;
+
+        /* MSI-X support */
+        int msix_enabled;
+        int intx_enabled;
+        struct msix_entry *msix_entries;
+        /* Name strings for interrupts. This size should be enough,
+         * and I'm too lazy to allocate each name separately. */
+        char (*msix_names)[256];
+        /* Number of available vectors */
+        unsigned msix_vectors;
+        /* Vectors allocated */
+        unsigned msix_used_vectors;
+};
+
+/* Constants for MSI-X */
+/* Use first vector for configuration changes, second and the rest for
+ * virtqueues Thus, we need at least 2 vectors for MSI. */
+enum {
+        VP_MSIX_CONFIG_VECTOR = 0,
+        VP_MSIX_VQ_VECTOR = 1,
 };
 
 struct virtio_pci_vq_info
@@ -60,6 +80,9 @@ struct virtio_pci_vq_info
 
         /* the list node for the virtqueues list */
         struct list_head node;
+
+        /* MSI-X vector (or none) */
+        unsigned vector;
 };
 
 /* Qumranet donated their vendor ID for devices 0x1000 thru 0x10FF. */
@@ -109,7 +132,8 @@ static void vp_get(struct virtio_device *vdev, unsigned offset,
                    void *buf, unsigned len)
 {
         struct virtio_pci_device *vp_dev = to_vp_device(vdev);
-        void __iomem *ioaddr = vp_dev->ioaddr + VIRTIO_PCI_CONFIG + offset;
+        void __iomem *ioaddr = vp_dev->ioaddr +
+                                VIRTIO_PCI_CONFIG(vp_dev) + offset;
         u8 *ptr = buf;
         int i;
 
@@ -123,7 +147,8 @@ static void vp_set(struct virtio_device *vdev, unsigned offset,
                    const void *buf, unsigned len)
 {
         struct virtio_pci_device *vp_dev = to_vp_device(vdev);
-        void __iomem *ioaddr = vp_dev->ioaddr + VIRTIO_PCI_CONFIG + offset;
+        void __iomem *ioaddr = vp_dev->ioaddr +
+                                VIRTIO_PCI_CONFIG(vp_dev) + offset;
         const u8 *ptr = buf;
         int i;
 
@@ -164,6 +189,37 @@ static void vp_notify(struct virtqueue *vq)
         iowrite16(info->queue_index, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_NOTIFY);
 }
 
+/* Handle a configuration change: Tell driver if it wants to know. */
+static irqreturn_t vp_config_changed(int irq, void *opaque)
+{
+        struct virtio_pci_device *vp_dev = opaque;
+        struct virtio_driver *drv;
+        drv = container_of(vp_dev->vdev.dev.driver,
+                           struct virtio_driver, driver);
+
+        if (drv && drv->config_changed)
+                drv->config_changed(&vp_dev->vdev);
+        return IRQ_HANDLED;
+}
+
+/* Notify all virtqueues on an interrupt. */
+static irqreturn_t vp_vring_interrupt(int irq, void *opaque)
+{
+        struct virtio_pci_device *vp_dev = opaque;
+        struct virtio_pci_vq_info *info;
+        irqreturn_t ret = IRQ_NONE;
+        unsigned long flags;
+
+        spin_lock_irqsave(&vp_dev->lock, flags);
+        list_for_each_entry(info, &vp_dev->virtqueues, node) {
+                if (vring_interrupt(irq, info->vq) == IRQ_HANDLED)
+                        ret = IRQ_HANDLED;
+        }
+        spin_unlock_irqrestore(&vp_dev->lock, flags);
+
+        return ret;
+}
+
 /* A small wrapper to also acknowledge the interrupt when it's handled.
  * I really need an EIO hook for the vring so I can ack the interrupt once we
  * know that we'll be handling the IRQ but before we invoke the callback since
@@ -173,9 +229,6 @@ static void vp_notify(struct virtqueue *vq)
 static irqreturn_t vp_interrupt(int irq, void *opaque)
 {
         struct virtio_pci_device *vp_dev = opaque;
-        struct virtio_pci_vq_info *info;
-        irqreturn_t ret = IRQ_NONE;
-        unsigned long flags;
         u8 isr;
 
         /* reading the ISR has the effect of also clearing it so it's very
@@ -187,34 +240,137 @@ static irqreturn_t vp_interrupt(int irq, void *opaque)
                 return IRQ_NONE;
 
         /* Configuration change?  Tell driver if it wants to know. */
-        if (isr & VIRTIO_PCI_ISR_CONFIG) {
-                struct virtio_driver *drv;
-                drv = container_of(vp_dev->vdev.dev.driver,
-                                   struct virtio_driver, driver);
+        if (isr & VIRTIO_PCI_ISR_CONFIG)
+                vp_config_changed(irq, opaque);
 
-                if (drv && drv->config_changed)
-                        drv->config_changed(&vp_dev->vdev);
+        return vp_vring_interrupt(irq, opaque);
+}
+
+static void vp_free_vectors(struct virtio_device *vdev)
+{
+        struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+        int i;
+
+        if (vp_dev->intx_enabled) {
+                free_irq(vp_dev->pci_dev->irq, vp_dev);
+                vp_dev->intx_enabled = 0;
         }
 
-        spin_lock_irqsave(&vp_dev->lock, flags);
-        list_for_each_entry(info, &vp_dev->virtqueues, node) {
-                if (vring_interrupt(irq, info->vq) == IRQ_HANDLED)
-                        ret = IRQ_HANDLED;
+        for (i = 0; i < vp_dev->msix_used_vectors; ++i)
+                free_irq(vp_dev->msix_entries[i].vector, vp_dev);
+        vp_dev->msix_used_vectors = 0;
+
+        if (vp_dev->msix_enabled) {
+                /* Disable the vector used for configuration */
+                iowrite16(VIRTIO_MSI_NO_VECTOR,
+                          vp_dev->ioaddr + VIRTIO_MSI_CONFIG_VECTOR);
+                /* Flush the write out to device */
+                ioread16(vp_dev->ioaddr + VIRTIO_MSI_CONFIG_VECTOR);
+
+                vp_dev->msix_enabled = 0;
+                pci_disable_msix(vp_dev->pci_dev);
         }
-        spin_unlock_irqrestore(&vp_dev->lock, flags);
+}
 
-        return ret;
+static int vp_enable_msix(struct pci_dev *dev, struct msix_entry *entries,
+                          int *options, int noptions)
+{
+        int i;
+        for (i = 0; i < noptions; ++i)
+                if (!pci_enable_msix(dev, entries, options[i]))
+                        return options[i];
+        return -EBUSY;
+}
+
+static int vp_request_vectors(struct virtio_device *vdev, unsigned max_vqs)
+{
+        struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+        const char *name = dev_name(&vp_dev->vdev.dev);
+        unsigned i, v;
+        int err = -ENOMEM;
+        /* We want at most one vector per queue and one for config changes.
+         * Fallback to separate vectors for config and a shared for queues.
+         * Finally fall back to regular interrupts. */
+        int options[] = { max_vqs + 1, 2 };
+        int nvectors = max(options[0], options[1]);
+
+        vp_dev->msix_entries = kmalloc(nvectors * sizeof *vp_dev->msix_entries,
+                                       GFP_KERNEL);
+        if (!vp_dev->msix_entries)
+                goto error_entries;
+        vp_dev->msix_names = kmalloc(nvectors * sizeof *vp_dev->msix_names,
+                                     GFP_KERNEL);
+        if (!vp_dev->msix_names)
+                goto error_names;
+
+        for (i = 0; i < nvectors; ++i)
+                vp_dev->msix_entries[i].entry = i;
+
+        err = vp_enable_msix(vp_dev->pci_dev, vp_dev->msix_entries,
+                             options, ARRAY_SIZE(options));
+        if (err < 0) {
+                /* Can't allocate enough MSI-X vectors, use regular interrupt */
+                vp_dev->msix_vectors = 0;
+                err = request_irq(vp_dev->pci_dev->irq, vp_interrupt,
+                                  IRQF_SHARED, name, vp_dev);
+                if (err)
+                        goto error_irq;
+                vp_dev->intx_enabled = 1;
+        } else {
+                vp_dev->msix_vectors = err;
+                vp_dev->msix_enabled = 1;
+
+                /* Set the vector used for configuration */
+                v = vp_dev->msix_used_vectors;
+                snprintf(vp_dev->msix_names[v], sizeof *vp_dev->msix_names,
+                         "%s-config", name);
+                err = request_irq(vp_dev->msix_entries[v].vector,
+                                  vp_config_changed, 0, vp_dev->msix_names[v],
+                                  vp_dev);
+                if (err)
+                        goto error_irq;
+                ++vp_dev->msix_used_vectors;
+
+                iowrite16(v, vp_dev->ioaddr + VIRTIO_MSI_CONFIG_VECTOR);
+                /* Verify we had enough resources to assign the vector */
+                v = ioread16(vp_dev->ioaddr + VIRTIO_MSI_CONFIG_VECTOR);
+                if (v == VIRTIO_MSI_NO_VECTOR) {
+                        err = -EBUSY;
+                        goto error_irq;
+                }
+        }
+
+        if (vp_dev->msix_vectors && vp_dev->msix_vectors != max_vqs + 1) {
+                /* Shared vector for all VQs */
+                v = vp_dev->msix_used_vectors;
+                snprintf(vp_dev->msix_names[v], sizeof *vp_dev->msix_names,
+                         "%s-virtqueues", name);
+                err = request_irq(vp_dev->msix_entries[v].vector,
+                                  vp_vring_interrupt, 0, vp_dev->msix_names[v],
+                                  vp_dev);
+                if (err)
+                        goto error_irq;
+                ++vp_dev->msix_used_vectors;
+        }
+        return 0;
+error_irq:
+        vp_free_vectors(vdev);
+        kfree(vp_dev->msix_names);
+error_names:
+        kfree(vp_dev->msix_entries);
+error_entries:
+        return err;
 }
 
-/* the config->find_vq() implementation */
 static struct virtqueue *vp_find_vq(struct virtio_device *vdev, unsigned index,
-                                    void (*callback)(struct virtqueue *vq))
+                                    void (*callback)(struct virtqueue *vq),
+                                    const char *name)
 {
         struct virtio_pci_device *vp_dev = to_vp_device(vdev);
         struct virtio_pci_vq_info *info;
         struct virtqueue *vq;
         unsigned long flags, size;
-        u16 num;
+        u16 num, vector;
         int err;
 
         /* Select the queue we're interested in */
@@ -233,6 +389,7 @@ static struct virtqueue *vp_find_vq(struct virtio_device *vdev, unsigned index,
 
         info->queue_index = index;
         info->num = num;
+        info->vector = VIRTIO_MSI_NO_VECTOR;
 
         size = PAGE_ALIGN(vring_size(num, VIRTIO_PCI_VRING_ALIGN));
         info->queue = alloc_pages_exact(size, GFP_KERNEL|__GFP_ZERO);
@@ -247,7 +404,7 @@ static struct virtqueue *vp_find_vq(struct virtio_device *vdev, unsigned index,
 
         /* create the vring */
         vq = vring_new_virtqueue(info->num, VIRTIO_PCI_VRING_ALIGN,
-                                 vdev, info->queue, vp_notify, callback);
+                                 vdev, info->queue, vp_notify, callback, name);
         if (!vq) {
                 err = -ENOMEM;
                 goto out_activate_queue;
@@ -256,12 +413,43 @@ static struct virtqueue *vp_find_vq(struct virtio_device *vdev, unsigned index,
         vq->priv = info;
         info->vq = vq;
 
+        /* allocate per-vq vector if available and necessary */
+        if (callback && vp_dev->msix_used_vectors < vp_dev->msix_vectors) {
+                vector = vp_dev->msix_used_vectors;
+                snprintf(vp_dev->msix_names[vector], sizeof *vp_dev->msix_names,
+                         "%s-%s", dev_name(&vp_dev->vdev.dev), name);
+                err = request_irq(vp_dev->msix_entries[vector].vector,
+                                  vring_interrupt, 0,
+                                  vp_dev->msix_names[vector], vq);
+                if (err)
+                        goto out_request_irq;
+                info->vector = vector;
+                ++vp_dev->msix_used_vectors;
+        } else
+                vector = VP_MSIX_VQ_VECTOR;
+
+         if (callback && vp_dev->msix_enabled) {
+                iowrite16(vector, vp_dev->ioaddr + VIRTIO_MSI_QUEUE_VECTOR);
+                vector = ioread16(vp_dev->ioaddr + VIRTIO_MSI_QUEUE_VECTOR);
+                if (vector == VIRTIO_MSI_NO_VECTOR) {
+                        err = -EBUSY;
+                        goto out_assign;
+                }
+        }
+
         spin_lock_irqsave(&vp_dev->lock, flags);
         list_add(&info->node, &vp_dev->virtqueues);
         spin_unlock_irqrestore(&vp_dev->lock, flags);
 
         return vq;
 
+out_assign:
+        if (info->vector != VIRTIO_MSI_NO_VECTOR) {
+                free_irq(vp_dev->msix_entries[info->vector].vector, vq);
+                --vp_dev->msix_used_vectors;
+        }
+out_request_irq:
+        vring_del_virtqueue(vq);
 out_activate_queue:
         iowrite32(0, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN);
         free_pages_exact(info->queue, size);
@@ -270,21 +458,27 @@ out_info:
         return ERR_PTR(err);
 }
 
-/* the config->del_vq() implementation */
 static void vp_del_vq(struct virtqueue *vq)
 {
         struct virtio_pci_device *vp_dev = to_vp_device(vq->vdev);
         struct virtio_pci_vq_info *info = vq->priv;
-        unsigned long flags, size;
+        unsigned long size;
 
-        spin_lock_irqsave(&vp_dev->lock, flags);
-        list_del(&info->node);
-        spin_unlock_irqrestore(&vp_dev->lock, flags);
+        iowrite16(info->queue_index, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_SEL);
+
+        if (info->vector != VIRTIO_MSI_NO_VECTOR)
+                free_irq(vp_dev->msix_entries[info->vector].vector, vq);
+
+        if (vp_dev->msix_enabled) {
+                iowrite16(VIRTIO_MSI_NO_VECTOR,
+                          vp_dev->ioaddr + VIRTIO_MSI_QUEUE_VECTOR);
+                /* Flush the write out to device */
+                ioread8(vp_dev->ioaddr + VIRTIO_PCI_ISR);
+        }
 
         vring_del_virtqueue(vq);
 
         /* Select and deactivate the queue */
-        iowrite16(info->queue_index, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_SEL);
         iowrite32(0, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN);
 
         size = PAGE_ALIGN(vring_size(info->num, VIRTIO_PCI_VRING_ALIGN));
@@ -292,14 +486,57 @@ static void vp_del_vq(struct virtqueue *vq)
         kfree(info);
 }
 
+/* the config->del_vqs() implementation */
+static void vp_del_vqs(struct virtio_device *vdev)
+{
+        struct virtqueue *vq, *n;
+
+        list_for_each_entry_safe(vq, n, &vdev->vqs, list)
+                vp_del_vq(vq);
+
+        vp_free_vectors(vdev);
+}
+
+/* the config->find_vqs() implementation */
+static int vp_find_vqs(struct virtio_device *vdev, unsigned nvqs,
+                       struct virtqueue *vqs[],
+                       vq_callback_t *callbacks[],
+                       const char *names[])
+{
+        int vectors = 0;
+        int i, err;
+
+        /* How many vectors would we like? */
+        for (i = 0; i < nvqs; ++i)
+                if (callbacks[i])
+                        ++vectors;
+
+        err = vp_request_vectors(vdev, vectors);
+        if (err)
+                goto error_request;
+
+        for (i = 0; i < nvqs; ++i) {
+                vqs[i] = vp_find_vq(vdev, i, callbacks[i], names[i]);
+                if (IS_ERR(vqs[i]))
+                        goto error_find;
+        }
+        return 0;
+
+error_find:
+        vp_del_vqs(vdev);
+
+error_request:
+        return PTR_ERR(vqs[i]);
+}
+
 static struct virtio_config_ops virtio_pci_config_ops = {
         .get            = vp_get,
         .set            = vp_set,
         .get_status     = vp_get_status,
         .set_status     = vp_set_status,
         .reset          = vp_reset,
-        .find_vq        = vp_find_vq,
-        .del_vq         = vp_del_vq,
+        .find_vqs       = vp_find_vqs,
+        .del_vqs        = vp_del_vqs,
         .get_features   = vp_get_features,
         .finalize_features = vp_finalize_features,
 };
@@ -310,7 +547,7 @@ static void virtio_pci_release_dev(struct device *_d)
         struct virtio_pci_device *vp_dev = to_vp_device(dev);
         struct pci_dev *pci_dev = vp_dev->pci_dev;
 
-        free_irq(pci_dev->irq, vp_dev);
+        vp_del_vqs(dev);
         pci_set_drvdata(pci_dev, NULL);
         pci_iounmap(pci_dev, vp_dev->ioaddr);
         pci_release_regions(pci_dev);
@@ -369,21 +606,13 @@ static int __devinit virtio_pci_probe(struct pci_dev *pci_dev,
         vp_dev->vdev.id.vendor = pci_dev->subsystem_vendor;
         vp_dev->vdev.id.device = pci_dev->subsystem_device;
 
-        /* register a handler for the queue with the PCI device's interrupt */
-        err = request_irq(vp_dev->pci_dev->irq, vp_interrupt, IRQF_SHARED,
-                          dev_name(&vp_dev->vdev.dev), vp_dev);
-        if (err)
-                goto out_set_drvdata;
-
         /* finally register the virtio device */
         err = register_virtio_device(&vp_dev->vdev);
         if (err)
-                goto out_req_irq;
+                goto out_set_drvdata;
 
         return 0;
 
-out_req_irq:
-        free_irq(pci_dev->irq, vp_dev);
 out_set_drvdata:
         pci_set_drvdata(pci_dev, NULL);
         pci_iounmap(pci_dev, vp_dev->ioaddr);
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 5c52369ab9bb..a882f2606515 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -23,21 +23,30 @@
 
 #ifdef DEBUG
 /* For development, we want to crash whenever the ring is screwed. */
-#define BAD_RING(_vq, fmt...)                   \
-        do { dev_err(&(_vq)->vq.vdev->dev, fmt); BUG(); } while(0)
+#define BAD_RING(_vq, fmt, args...)                             \
+        do {                                                    \
+                dev_err(&(_vq)->vq.vdev->dev,                   \
+                        "%s:"fmt, (_vq)->vq.name, ##args);      \
+                BUG();                                          \
+        } while (0)
 /* Caller is supposed to guarantee no reentry. */
 #define START_USE(_vq)                                          \
         do {                                                    \
                 if ((_vq)->in_use)                              \
-                        panic("in_use = %i\n", (_vq)->in_use);  \
+                        panic("%s:in_use = %i\n",               \
+                              (_vq)->vq.name, (_vq)->in_use);   \
                 (_vq)->in_use = __LINE__;                       \
                 mb();                                           \
-        } while(0)
+        } while (0)
 #define END_USE(_vq) \
         do { BUG_ON(!(_vq)->in_use); (_vq)->in_use = 0; mb(); } while(0)
 #else
-#define BAD_RING(_vq, fmt...)                   \
-        do { dev_err(&_vq->vq.vdev->dev, fmt); (_vq)->broken = true; } while(0)
+#define BAD_RING(_vq, fmt, args...)                             \
+        do {                                                    \
+                dev_err(&_vq->vq.vdev->dev,                     \
+                        "%s:"fmt, (_vq)->vq.name, ##args);      \
+                (_vq)->broken = true;                           \
+        } while (0)
 #define START_USE(vq)
 #define END_USE(vq)
 #endif
@@ -52,6 +61,9 @@ struct vring_virtqueue
         /* Other side has made a mess, don't try any more. */
         bool broken;
 
+        /* Host supports indirect buffers */
+        bool indirect;
+
         /* Number of free buffers */
         unsigned int num_free;
         /* Head of free buffer list. */
@@ -76,6 +88,55 @@ struct vring_virtqueue
 
 #define to_vvq(_vq) container_of(_vq, struct vring_virtqueue, vq)
 
+/* Set up an indirect table of descriptors and add it to the queue. */
+static int vring_add_indirect(struct vring_virtqueue *vq,
+                              struct scatterlist sg[],
+                              unsigned int out,
+                              unsigned int in)
+{
+        struct vring_desc *desc;
+        unsigned head;
+        int i;
+
+        desc = kmalloc((out + in) * sizeof(struct vring_desc), GFP_ATOMIC);
+        if (!desc)
+                return vq->vring.num;
+
+        /* Transfer entries from the sg list into the indirect page */
+        for (i = 0; i < out; i++) {
+                desc[i].flags = VRING_DESC_F_NEXT;
+                desc[i].addr = sg_phys(sg);
+                desc[i].len = sg->length;
+                desc[i].next = i+1;
+                sg++;
+        }
+        for (; i < (out + in); i++) {
+                desc[i].flags = VRING_DESC_F_NEXT|VRING_DESC_F_WRITE;
+                desc[i].addr = sg_phys(sg);
+                desc[i].len = sg->length;
+                desc[i].next = i+1;
+                sg++;
+        }
+
+        /* Last one doesn't continue. */
+        desc[i-1].flags &= ~VRING_DESC_F_NEXT;
+        desc[i-1].next = 0;
+
+        /* We're about to use a buffer */
+        vq->num_free--;
+
+        /* Use a single buffer which doesn't continue */
+        head = vq->free_head;
+        vq->vring.desc[head].flags = VRING_DESC_F_INDIRECT;
+        vq->vring.desc[head].addr = virt_to_phys(desc);
+        vq->vring.desc[head].len = i * sizeof(struct vring_desc);
+
+        /* Update free pointer */
+        vq->free_head = vq->vring.desc[head].next;
+
+        return head;
+}
+
 static int vring_add_buf(struct virtqueue *_vq,
                          struct scatterlist sg[],
                          unsigned int out,
@@ -85,12 +146,21 @@ static int vring_add_buf(struct virtqueue *_vq,
         struct vring_virtqueue *vq = to_vvq(_vq);
         unsigned int i, avail, head, uninitialized_var(prev);
 
+        START_USE(vq);
+
         BUG_ON(data == NULL);
+
+        /* If the host supports indirect descriptor tables, and we have multiple
+         * buffers, then go indirect. FIXME: tune this threshold */
+        if (vq->indirect && (out + in) > 1 && vq->num_free) {
+                head = vring_add_indirect(vq, sg, out, in);
+                if (head != vq->vring.num)
+                        goto add_head;
+        }
+
         BUG_ON(out + in > vq->vring.num);
         BUG_ON(out + in == 0);
 
-        START_USE(vq);
-
         if (vq->num_free < out + in) {
                 pr_debug("Can't add buf len %i - avail = %i\n",
                          out + in, vq->num_free);
@@ -127,6 +197,7 @@ static int vring_add_buf(struct virtqueue *_vq,
         /* Update free pointer */
         vq->free_head = i;
 
+add_head:
         /* Set token. */
         vq->data[head] = data;
 
@@ -170,6 +241,11 @@ static void detach_buf(struct vring_virtqueue *vq, unsigned int head)
 
         /* Put back on free list: find end */
         i = head;
+
+        /* Free the indirect table */
+        if (vq->vring.desc[i].flags & VRING_DESC_F_INDIRECT)
+                kfree(phys_to_virt(vq->vring.desc[i].addr));
+
         while (vq->vring.desc[i].flags & VRING_DESC_F_NEXT) {
                 i = vq->vring.desc[i].next;
                 vq->num_free++;
@@ -284,7 +360,8 @@ struct virtqueue *vring_new_virtqueue(unsigned int num,
                                       struct virtio_device *vdev,
                                       void *pages,
                                       void (*notify)(struct virtqueue *),
-                                      void (*callback)(struct virtqueue *))
+                                      void (*callback)(struct virtqueue *),
+                                      const char *name)
 {
         struct vring_virtqueue *vq;
         unsigned int i;
@@ -303,14 +380,18 @@ struct virtqueue *vring_new_virtqueue(unsigned int num,
         vq->vq.callback = callback;
         vq->vq.vdev = vdev;
         vq->vq.vq_ops = &vring_vq_ops;
+        vq->vq.name = name;
         vq->notify = notify;
         vq->broken = false;
         vq->last_used_idx = 0;
         vq->num_added = 0;
+        list_add_tail(&vq->vq.list, &vdev->vqs);
 #ifdef DEBUG
         vq->in_use = false;
 #endif
 
+        vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC);
+
         /* No callback?  Tell other side not to bother us. */
         if (!callback)
                 vq->vring.avail->flags |= VRING_AVAIL_F_NO_INTERRUPT;
@@ -327,6 +408,7 @@ EXPORT_SYMBOL_GPL(vring_new_virtqueue);
 
 void vring_del_virtqueue(struct virtqueue *vq)
 {
+        list_del(&vq->list);
         kfree(to_vvq(vq));
 }
 EXPORT_SYMBOL_GPL(vring_del_virtqueue);
@@ -338,6 +420,8 @@ void vring_transport_features(struct virtio_device *vdev)
 
         for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++) {
                 switch (i) {
+                case VIRTIO_RING_F_INDIRECT_DESC:
+                        break;
                 default:
                         /* We don't understand this bit. */
                         clear_bit(i, vdev->features);