[Xen-devel] [PATCH v6 7/9] virtio_mmio: Use the DMA API if enabled

[Andy Lutomirski <luto@xxxxxxxxxx>]

This switches to vring_create_virtqueue, simplifying the driver and
adding DMA API support.

Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
---
 drivers/virtio/virtio_mmio.c | 67 ++++++++++----------------------------------
 1 file changed, 15 insertions(+), 52 deletions(-)

diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
index 745c6ee1bb3e..48bfea91dbca 100644
--- a/drivers/virtio/virtio_mmio.c
+++ b/drivers/virtio/virtio_mmio.c
@@ -99,12 +99,6 @@ struct virtio_mmio_vq_info {
        /* the actual virtqueue */
        struct virtqueue *vq;
 
-       /* the number of entries in the queue */
-       unsigned int num;
-
-       /* the virtual address of the ring queue */
-       void *queue;
-
        /* the list node for the virtqueues list */
        struct list_head node;
 };
@@ -322,15 +316,13 @@ static void vm_del_vq(struct virtqueue *vq)
 {
        struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vq->vdev);
        struct virtio_mmio_vq_info *info = vq->priv;
-       unsigned long flags, size;
+       unsigned long flags;
        unsigned int index = vq->index;
 
        spin_lock_irqsave(&vm_dev->lock, flags);
        list_del(&info->node);
        spin_unlock_irqrestore(&vm_dev->lock, flags);
 
-       vring_del_virtqueue(vq);
-
        /* Select and deactivate the queue */
        writel(index, vm_dev->base + VIRTIO_MMIO_QUEUE_SEL);
        if (vm_dev->version == 1) {
@@ -340,8 +332,8 @@ static void vm_del_vq(struct virtqueue *vq)
                WARN_ON(readl(vm_dev->base + VIRTIO_MMIO_QUEUE_READY));
        }
 
-       size = PAGE_ALIGN(vring_size(info->num, VIRTIO_MMIO_VRING_ALIGN));
-       free_pages_exact(info->queue, size);
+       vring_del_virtqueue(vq);
+
        kfree(info);
 }
 
@@ -356,8 +348,6 @@ static void vm_del_vqs(struct virtio_device *vdev)
        free_irq(platform_get_irq(vm_dev->pdev, 0), vm_dev);
 }
 
-
-
 static struct virtqueue *vm_setup_vq(struct virtio_device *vdev, unsigned 
index,
                                  void (*callback)(struct virtqueue *vq),
                                  const char *name)
@@ -365,7 +355,8 @@ static struct virtqueue *vm_setup_vq(struct virtio_device 
*vdev, unsigned index,
        struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
        struct virtio_mmio_vq_info *info;
        struct virtqueue *vq;
-       unsigned long flags, size;
+       unsigned long flags;
+       unsigned int num;
        int err;
 
        if (!name)
@@ -388,66 +379,40 @@ static struct virtqueue *vm_setup_vq(struct virtio_device 
*vdev, unsigned index,
                goto error_kmalloc;
        }
 
-       /* Allocate pages for the queue - start with a queue as big as
-        * possible (limited by maximum size allowed by device), drop down
-        * to a minimal size, just big enough to fit descriptor table
-        * and two rings (which makes it "alignment_size * 2")
-        */
-       info->num = readl(vm_dev->base + VIRTIO_MMIO_QUEUE_NUM_MAX);
-
-       /* If the device reports a 0 entry queue, we won't be able to
-        * use it to perform I/O, and vring_new_virtqueue() can't create
-        * empty queues anyway, so don't bother to set up the device.
-        */
-       if (info->num == 0) {
+       num = readl(vm_dev->base + VIRTIO_MMIO_QUEUE_NUM_MAX);
+       if (num == 0) {
                err = -ENOENT;
-               goto error_alloc_pages;
-       }
-
-       while (1) {
-               size = PAGE_ALIGN(vring_size(info->num,
-                               VIRTIO_MMIO_VRING_ALIGN));
-               /* Did the last iter shrink the queue below minimum size? */
-               if (size < VIRTIO_MMIO_VRING_ALIGN * 2) {
-                       err = -ENOMEM;
-                       goto error_alloc_pages;
-               }
-
-               info->queue = alloc_pages_exact(size, GFP_KERNEL | __GFP_ZERO);
-               if (info->queue)
-                       break;
-
-               info->num /= 2;
+               goto error_new_virtqueue;
        }
 
        /* Create the vring */
-       vq = vring_new_virtqueue(index, info->num, VIRTIO_MMIO_VRING_ALIGN, 
vdev,
-                                true, info->queue, vm_notify, callback, name);
+       vq = vring_create_virtqueue(index, num, VIRTIO_MMIO_VRING_ALIGN, vdev,
+                                true, true, vm_notify, callback, name);
        if (!vq) {
                err = -ENOMEM;
                goto error_new_virtqueue;
        }
 
        /* Activate the queue */
-       writel(info->num, vm_dev->base + VIRTIO_MMIO_QUEUE_NUM);
+       writel(virtqueue_get_vring_size(vq), vm_dev->base + 
VIRTIO_MMIO_QUEUE_NUM);
        if (vm_dev->version == 1) {
                writel(PAGE_SIZE, vm_dev->base + VIRTIO_MMIO_QUEUE_ALIGN);
-               writel(virt_to_phys(info->queue) >> PAGE_SHIFT,
+               writel(virtqueue_get_desc_addr(vq) >> PAGE_SHIFT,
                                vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
        } else {
                u64 addr;
 
-               addr = virt_to_phys(info->queue);
+               addr = virtqueue_get_desc_addr(vq);
                writel((u32)addr, vm_dev->base + VIRTIO_MMIO_QUEUE_DESC_LOW);
                writel((u32)(addr >> 32),
                                vm_dev->base + VIRTIO_MMIO_QUEUE_DESC_HIGH);
 
-               addr = virt_to_phys(virtqueue_get_avail(vq));
+               addr = virtqueue_get_avail_addr(vq);
                writel((u32)addr, vm_dev->base + VIRTIO_MMIO_QUEUE_AVAIL_LOW);
                writel((u32)(addr >> 32),
                                vm_dev->base + VIRTIO_MMIO_QUEUE_AVAIL_HIGH);
 
-               addr = virt_to_phys(virtqueue_get_used(vq));
+               addr = virtqueue_get_used_addr(vq);
                writel((u32)addr, vm_dev->base + VIRTIO_MMIO_QUEUE_USED_LOW);
                writel((u32)(addr >> 32),
                                vm_dev->base + VIRTIO_MMIO_QUEUE_USED_HIGH);
@@ -471,8 +436,6 @@ error_new_virtqueue:
                writel(0, vm_dev->base + VIRTIO_MMIO_QUEUE_READY);
                WARN_ON(readl(vm_dev->base + VIRTIO_MMIO_QUEUE_READY));
        }
-       free_pages_exact(info->queue, size);
-error_alloc_pages:
        kfree(info);
 error_kmalloc:
 error_available:
-- 
2.5.0


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