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

From: Andy Lutomirski
Date: Mon Feb 01 2016 - 13:01:24 EST


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