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virtio: allow virtio-1 queue layout
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For virtio-1 devices, we allow a more complex queue layout that doesn't
require descriptor table and rings on a physically-contigous memory area:
add virtio_queue_set_rings() to allow transports to set this up.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
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@cohuck @mstsirkin
cohuck authored and mstsirkin committed Jun 10, 2015
1 parent 3c18559 commit ab223c9
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Showing 3 changed files with 40 additions and 19 deletions.
3 changes: 3 additions & 0 deletions hw/virtio/virtio-mmio.c
View file
Expand Up @@ -333,8 +333,11 @@ static void virtio_mmio_write(void *opaque, hwaddr offset, uint64_t value,
case VIRTIO_MMIO_QUEUENUM:
DPRINTF("mmio_queue write %d max %d\n", (int)value, VIRTQUEUE_MAX_SIZE);
virtio_queue_set_num(vdev, vdev->queue_sel, value);
/* Note: only call this function for legacy devices */
virtio_queue_update_rings(vdev, vdev->queue_sel);
break;
case VIRTIO_MMIO_QUEUEALIGN:
/* Note: this is only valid for legacy devices */
virtio_queue_set_align(vdev, vdev->queue_sel, value);
break;
case VIRTIO_MMIO_QUEUEPFN:
Expand Down
53 changes: 34 additions & 19 deletions hw/virtio/virtio.c
View file
Expand Up @@ -69,7 +69,6 @@ typedef struct VRing
struct VirtQueue
{
VRing vring;
hwaddr pa;
uint16_t last_avail_idx;
/* Last used index value we have signalled on */
uint16_t signalled_used;
Expand All @@ -93,15 +92,18 @@ struct VirtQueue
};

/* virt queue functions */
static void virtqueue_init(VirtQueue *vq)
void virtio_queue_update_rings(VirtIODevice *vdev, int n)
{
hwaddr pa = vq->pa;
VRing *vring = &vdev->vq[n].vring;

vq->vring.desc = pa;
vq->vring.avail = pa + vq->vring.num * sizeof(VRingDesc);
vq->vring.used = vring_align(vq->vring.avail +
offsetof(VRingAvail, ring[vq->vring.num]),
vq->vring.align);
if (!vring->desc) {
/* not yet setup -> nothing to do */
return;
}
vring->avail = vring->desc + vring->num * sizeof(VRingDesc);
vring->used = vring_align(vring->avail +
offsetof(VRingAvail, ring[vring->num]),
vring->align);
}

static inline uint64_t vring_desc_addr(VirtIODevice *vdev, hwaddr desc_pa,
Expand Down Expand Up @@ -605,7 +607,6 @@ void virtio_reset(void *opaque)
vdev->vq[i].vring.avail = 0;
vdev->vq[i].vring.used = 0;
vdev->vq[i].last_avail_idx = 0;
vdev->vq[i].pa = 0;
virtio_queue_set_vector(vdev, i, VIRTIO_NO_VECTOR);
vdev->vq[i].signalled_used = 0;
vdev->vq[i].signalled_used_valid = false;
Expand Down Expand Up @@ -708,13 +709,21 @@ void virtio_config_writel(VirtIODevice *vdev, uint32_t addr, uint32_t data)

void virtio_queue_set_addr(VirtIODevice *vdev, int n, hwaddr addr)
{
vdev->vq[n].pa = addr;
virtqueue_init(&vdev->vq[n]);
vdev->vq[n].vring.desc = addr;
virtio_queue_update_rings(vdev, n);
}

hwaddr virtio_queue_get_addr(VirtIODevice *vdev, int n)
{
return vdev->vq[n].pa;
return vdev->vq[n].vring.desc;
}

void virtio_queue_set_rings(VirtIODevice *vdev, int n, hwaddr desc,
hwaddr avail, hwaddr used)
{
vdev->vq[n].vring.desc = desc;
vdev->vq[n].vring.avail = avail;
vdev->vq[n].vring.used = used;
}

void virtio_queue_set_num(VirtIODevice *vdev, int n, int num)
Expand All @@ -728,7 +737,6 @@ void virtio_queue_set_num(VirtIODevice *vdev, int n, int num)
return;
}
vdev->vq[n].vring.num = num;
virtqueue_init(&vdev->vq[n]);
}

VirtQueue *virtio_vector_first_queue(VirtIODevice *vdev, uint16_t vector)
Expand Down Expand Up @@ -771,14 +779,19 @@ void virtio_queue_set_align(VirtIODevice *vdev, int n, int align)
BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);

/* virtio-1 compliant devices cannot change the alignment */
if (virtio_has_feature(vdev, VIRTIO_F_VERSION_1)) {
error_report("tried to modify queue alignment for virtio-1 device");
return;
}
/* Check that the transport told us it was going to do this
* (so a buggy transport will immediately assert rather than
* silently failing to migrate this state)
*/
assert(k->has_variable_vring_alignment);

vdev->vq[n].vring.align = align;
virtqueue_init(&vdev->vq[n]);
virtio_queue_update_rings(vdev, n);
}

void virtio_queue_notify_vq(VirtQueue *vq)
Expand Down Expand Up @@ -992,7 +1005,8 @@ void virtio_save(VirtIODevice *vdev, QEMUFile *f)
if (k->has_variable_vring_alignment) {
qemu_put_be32(f, vdev->vq[i].vring.align);
}
qemu_put_be64(f, vdev->vq[i].pa);
/* XXX virtio-1 devices */
qemu_put_be64(f, vdev->vq[i].vring.desc);
qemu_put_be16s(f, &vdev->vq[i].last_avail_idx);
if (k->save_queue) {
k->save_queue(qbus->parent, i, f);
Expand Down Expand Up @@ -1076,13 +1090,14 @@ int virtio_load(VirtIODevice *vdev, QEMUFile *f, int version_id)
if (k->has_variable_vring_alignment) {
vdev->vq[i].vring.align = qemu_get_be32(f);
}
vdev->vq[i].pa = qemu_get_be64(f);
vdev->vq[i].vring.desc = qemu_get_be64(f);
qemu_get_be16s(f, &vdev->vq[i].last_avail_idx);
vdev->vq[i].signalled_used_valid = false;
vdev->vq[i].notification = true;

if (vdev->vq[i].pa) {
virtqueue_init(&vdev->vq[i]);
if (vdev->vq[i].vring.desc) {
/* XXX virtio-1 devices */
virtio_queue_update_rings(vdev, i);
} else if (vdev->vq[i].last_avail_idx) {
error_report("VQ %d address 0x0 "
"inconsistent with Host index 0x%x",
Expand Down Expand Up @@ -1138,7 +1153,7 @@ int virtio_load(VirtIODevice *vdev, QEMUFile *f, int version_id)
}

for (i = 0; i < num; i++) {
if (vdev->vq[i].pa) {
if (vdev->vq[i].vring.desc) {
uint16_t nheads;
nheads = vring_avail_idx(&vdev->vq[i]) - vdev->vq[i].last_avail_idx;
/* Check it isn't doing strange things with descriptor numbers. */
Expand Down
3 changes: 3 additions & 0 deletions include/hw/virtio/virtio.h
View file
Expand Up @@ -177,6 +177,9 @@ hwaddr virtio_queue_get_addr(VirtIODevice *vdev, int n);
void virtio_queue_set_num(VirtIODevice *vdev, int n, int num);
int virtio_queue_get_num(VirtIODevice *vdev, int n);
int virtio_get_num_queues(VirtIODevice *vdev);
void virtio_queue_set_rings(VirtIODevice *vdev, int n, hwaddr desc,
hwaddr avail, hwaddr used);
void virtio_queue_update_rings(VirtIODevice *vdev, int n);
void virtio_queue_set_align(VirtIODevice *vdev, int n, int align);
void virtio_queue_notify(VirtIODevice *vdev, int n);
uint16_t virtio_queue_vector(VirtIODevice *vdev, int n);
Expand Down

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