* Laurent Vivier (lviv...@redhat.com) wrote:
> This new command shows the information of a VirtQueue element.
Having had a few second play with this, I think I've always seen it say
that the ring is empty; is this pretty much always the case when the VM
is running and the device is consuming elements off the queue - so most
cases where this is useful is where the VM is paused?
> + desc_cache = &caches->desc;
> + vring_split_desc_read(vdev, &desc, desc_cache, i);
> + if (desc.flags & VRING_DESC_F_INDIRECT) {
> + error_setg(errp, "Unsupported indirect buffer feature");
> + return NULL;
> + }
I did trigger this in the case I was playing with.
Dave
> + element = g_new0(VirtioQueueElement, 1);
> + element->index = head;
> + element->ndescs = 1;
> + element->descs = g_new0(VirtioRingDescList, 1);
> + element->descs->value = g_new0(VirtioRingDesc, 1);
> + element->descs->value->addr = desc.addr;
> + element->descs->value->len = desc.len;
> + element->descs->value->flags = desc.flags;
> + }
> +
> + return element;
> +}
> +
> static const TypeInfo virtio_device_info = {
> .name = TYPE_VIRTIO_DEVICE,
> .parent = TYPE_DEVICE,
> diff --git a/qapi/virtio.json b/qapi/virtio.json
> index ab70500d919b..3e8865511217 100644
> --- a/qapi/virtio.json
> +++ b/qapi/virtio.json
> @@ -215,3 +215,88 @@
> 'data': { 'path': 'str', 'queue': 'uint16' },
> 'returns': 'VirtQueueStatus'
> }
> +
> +##
> +# @VirtioRingDesc:
> +#
> +# @addr: guest physical address of the descriptor data
> +#
> +# @len: length of the descriptor data
> +#
> +# @flags: descriptor flags (write-only, read-only, ...)
> +#
> +# Since: 5.1
> +#
> +##
> +
> +{ 'struct': 'VirtioRingDesc',
> + 'data': {
> + 'addr': 'uint64',
> + 'len': 'uint32',
> + 'flags': 'uint16'
> + }
> +}
> +
> +##
> +# @VirtioQueueElement:
> +#
> +# @index: index of the element in the queue
> +#
> +# @len: length of the element data
> +#
> +# @ndescs: number of descriptors
> +#
> +# @descs: list of the descriptors
> +#
> +# Since: 5.1
> +#
> +##
> +
> +{ 'struct': 'VirtioQueueElement',
> + 'data': {
> + 'index': 'uint32',
> + 'len': 'uint32',
> + 'ndescs': 'uint32',
> + 'descs': ['VirtioRingDesc']
> + }
> +}
> +
> +##
> +# @virtio-queue-element:
> +#
> +# Return the information about an element queue (by default head)
> +#
> +# @path: QOBject path of the VirtIODevice
> +#
> +# @queue: queue number to examine
> +#
> +# @index: the index in the queue, by default head
> +#
> +# Returns: the element information
> +#
> +# Since: 5.1
> +#
> +# Example:
> +#
> +# -> { "execute": "virtio-queue-element",
> +# "arguments": {
> +# "path": "/machine/peripheral-anon/device[3]/virtio-backend",
> +# "queue": 0
> +# }
> +# }
> +# -> { "return": {
> +# "index": 109,
> +# "len": 0,
> +# "ndescs": 1,
> +# "descs": [
> +# { "flags": 2, "len": 2048, "addr": 853145600 }
> +# ]
> +# }
> +# }
> +#
> +##
> +
> +{ 'command': 'virtio-queue-element',
> + 'data': { 'path': 'str', 'queue': 'uint16', '*index': 'uint16' },
> + 'returns': 'VirtioQueueElement'
> +}
> --
> 2.25.1
>
--
Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
