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virtio: use address_space_map/unmap to access descriptors
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This makes little difference, but it makes the code change smaller
for the next patch that introduces MemoryRegionCache.  This is
because map/unmap are similar to MemoryRegionCache init/destroy.

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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@bonzini @mstsirkin
bonzini authored and mstsirkin committed Feb 17, 2017
1 parent e6a830d commit 9796d0a
Showing 1 changed file with 75 additions and 28 deletions.
103 changes: 75 additions & 28 deletions hw/virtio/virtio.c
View file
Expand Up @@ -120,10 +120,9 @@ void virtio_queue_update_rings(VirtIODevice *vdev, int n)
}

static void vring_desc_read(VirtIODevice *vdev, VRingDesc *desc,
hwaddr desc_pa, int i)
uint8_t *desc_ptr, int i)
{
address_space_read(vdev->dma_as, desc_pa + i * sizeof(VRingDesc),
MEMTXATTRS_UNSPECIFIED, (void *)desc, sizeof(VRingDesc));
memcpy(desc, desc_ptr + i * sizeof(VRingDesc), sizeof(VRingDesc));
virtio_tswap64s(vdev, &desc->addr);
virtio_tswap32s(vdev, &desc->len);
virtio_tswap16s(vdev, &desc->flags);
Expand Down Expand Up @@ -408,7 +407,7 @@ enum {
};

static int virtqueue_read_next_desc(VirtIODevice *vdev, VRingDesc *desc,
hwaddr desc_pa, unsigned int max,
void *desc_ptr, unsigned int max,
unsigned int *next)
{
/* If this descriptor says it doesn't chain, we're done. */
Expand All @@ -426,39 +425,49 @@ static int virtqueue_read_next_desc(VirtIODevice *vdev, VRingDesc *desc,
return VIRTQUEUE_READ_DESC_ERROR;
}

vring_desc_read(vdev, desc, desc_pa, *next);
vring_desc_read(vdev, desc, desc_ptr, *next);
return VIRTQUEUE_READ_DESC_MORE;
}

void virtqueue_get_avail_bytes(VirtQueue *vq, unsigned int *in_bytes,
unsigned int *out_bytes,
unsigned max_in_bytes, unsigned max_out_bytes)
{
unsigned int idx;
VirtIODevice *vdev = vq->vdev;
unsigned int max, idx;
unsigned int total_bufs, in_total, out_total;
void *vring_desc_ptr;
void *indirect_desc_ptr = NULL;
hwaddr len = 0;
int rc;

idx = vq->last_avail_idx;

total_bufs = in_total = out_total = 0;

max = vq->vring.num;
len = max * sizeof(VRingDesc);
vring_desc_ptr = address_space_map(vdev->dma_as, vq->vring.desc, &len, false);
if (len < max * sizeof(VRingDesc)) {
virtio_error(vdev, "Cannot map descriptor ring");
goto err;
}

while ((rc = virtqueue_num_heads(vq, idx)) > 0) {
VirtIODevice *vdev = vq->vdev;
unsigned int max, num_bufs, indirect = 0;
void *desc_ptr = vring_desc_ptr;
unsigned int num_bufs;
VRingDesc desc;
hwaddr desc_pa;
unsigned int i;

max = vq->vring.num;
num_bufs = total_bufs;

if (!virtqueue_get_head(vq, idx++, &i)) {
goto err;
}

desc_pa = vq->vring.desc;
vring_desc_read(vdev, &desc, desc_pa, i);
vring_desc_read(vdev, &desc, desc_ptr, i);

if (desc.flags & VRING_DESC_F_INDIRECT) {
len = desc.len;
if (desc.len % sizeof(VRingDesc)) {
virtio_error(vdev, "Invalid size for indirect buffer table");
goto err;
Expand All @@ -471,11 +480,17 @@ void virtqueue_get_avail_bytes(VirtQueue *vq, unsigned int *in_bytes,
}

/* loop over the indirect descriptor table */
indirect = 1;
indirect_desc_ptr = address_space_map(vdev->dma_as, desc.addr,
&len, false);
desc_ptr = indirect_desc_ptr;
if (len < desc.len) {
virtio_error(vdev, "Cannot map indirect buffer");
goto err;
}

max = desc.len / sizeof(VRingDesc);
desc_pa = desc.addr;
num_bufs = i = 0;
vring_desc_read(vdev, &desc, desc_pa, i);
vring_desc_read(vdev, &desc, desc_ptr, i);
}

do {
Expand All @@ -494,24 +509,31 @@ void virtqueue_get_avail_bytes(VirtQueue *vq, unsigned int *in_bytes,
goto done;
}

rc = virtqueue_read_next_desc(vdev, &desc, desc_pa, max, &i);
rc = virtqueue_read_next_desc(vdev, &desc, desc_ptr, max, &i);
} while (rc == VIRTQUEUE_READ_DESC_MORE);

if (rc == VIRTQUEUE_READ_DESC_ERROR) {
goto err;
}

if (!indirect)
total_bufs = num_bufs;
else
if (desc_ptr == indirect_desc_ptr) {
address_space_unmap(vdev->dma_as, desc_ptr, len, false, 0);
indirect_desc_ptr = NULL;
total_bufs++;
} else {
total_bufs = num_bufs;
}
}

if (rc < 0) {
goto err;
}

done:
if (indirect_desc_ptr) {
address_space_unmap(vdev->dma_as, indirect_desc_ptr, len, false, 0);
}
address_space_unmap(vdev->dma_as, vring_desc_ptr, len, false, 0);
if (in_bytes) {
*in_bytes = in_total;
}
Expand Down Expand Up @@ -651,9 +673,12 @@ static void *virtqueue_alloc_element(size_t sz, unsigned out_num, unsigned in_nu
void *virtqueue_pop(VirtQueue *vq, size_t sz)
{
unsigned int i, head, max;
hwaddr desc_pa = vq->vring.desc;
void *vring_desc_ptr;
void *indirect_desc_ptr = NULL;
void *desc_ptr;
hwaddr len;
VirtIODevice *vdev = vq->vdev;
VirtQueueElement *elem;
VirtQueueElement *elem = NULL;
unsigned out_num, in_num;
hwaddr addr[VIRTQUEUE_MAX_SIZE];
struct iovec iov[VIRTQUEUE_MAX_SIZE];
Expand Down Expand Up @@ -689,18 +714,34 @@ void *virtqueue_pop(VirtQueue *vq, size_t sz)
}

i = head;
vring_desc_read(vdev, &desc, desc_pa, i);

len = max * sizeof(VRingDesc);
vring_desc_ptr = address_space_map(vdev->dma_as, vq->vring.desc, &len, false);
if (len < max * sizeof(VRingDesc)) {
virtio_error(vdev, "Cannot map descriptor ring");
goto done;
}

desc_ptr = vring_desc_ptr;
vring_desc_read(vdev, &desc, desc_ptr, i);
if (desc.flags & VRING_DESC_F_INDIRECT) {
if (desc.len % sizeof(VRingDesc)) {
virtio_error(vdev, "Invalid size for indirect buffer table");
return NULL;
goto done;
}

/* loop over the indirect descriptor table */
len = desc.len;
indirect_desc_ptr = address_space_map(vdev->dma_as, desc.addr, &len, false);
desc_ptr = indirect_desc_ptr;
if (len < desc.len) {
virtio_error(vdev, "Cannot map indirect buffer");
goto done;
}

max = desc.len / sizeof(VRingDesc);
desc_pa = desc.addr;
i = 0;
vring_desc_read(vdev, &desc, desc_pa, i);
vring_desc_read(vdev, &desc, desc_ptr, i);
}

/* Collect all the descriptors */
Expand Down Expand Up @@ -731,7 +772,7 @@ void *virtqueue_pop(VirtQueue *vq, size_t sz)
goto err_undo_map;
}

rc = virtqueue_read_next_desc(vdev, &desc, desc_pa, max, &i);
rc = virtqueue_read_next_desc(vdev, &desc, desc_ptr, max, &i);
} while (rc == VIRTQUEUE_READ_DESC_MORE);

if (rc == VIRTQUEUE_READ_DESC_ERROR) {
Expand All @@ -753,11 +794,17 @@ void *virtqueue_pop(VirtQueue *vq, size_t sz)
vq->inuse++;

trace_virtqueue_pop(vq, elem, elem->in_num, elem->out_num);
done:
if (indirect_desc_ptr) {
address_space_unmap(vdev->dma_as, indirect_desc_ptr, len, false, 0);
}
address_space_unmap(vdev->dma_as, vring_desc_ptr, len, false, 0);

return elem;

err_undo_map:
virtqueue_undo_map_desc(out_num, in_num, iov);
return NULL;
goto done;
}

/* virtqueue_drop_all:
Expand Down

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