Hi Jason, could I get your thoughts on this implementation question below?
I'm not too sure on how I should proceed determining if vhost is active or not.
Thank you! Jonah On 7/26/21 5:33 AM, Jonah Palmer wrote:
On 7/22/21 5:22 AM, Jason Wang wrote:在 2021/7/21 下午4:59, Jonah Palmer 写道:On 7/13/21 10:37 PM, Jason Wang wrote:Got it. I'll add a case to determine if vhost is active for a given device. So, in the case that vhost is active, should I just not print out the value or would I substitute it with在 2021/7/12 下午6:35, Jonah Palmer 写道:From: Laurent Vivier <lviv...@redhat.com> This new command shows internal status of a VirtQueue. (vrings and indexes). Signed-off-by: Laurent Vivier <lviv...@redhat.com> Signed-off-by: Jonah Palmer <jonah.pal...@oracle.com> --- hw/virtio/virtio-stub.c | 6 +++ hw/virtio/virtio.c | 37 ++++++++++++++++++qapi/virtio.json | 102 ++++++++++++++++++++++++++++++++++++++++++++++++3 files changed, 145 insertions(+) [Jonah: Added 'device-type' field to VirtQueueStatus and qmp command x-debug-virtio-queue-status.] diff --git a/hw/virtio/virtio-stub.c b/hw/virtio/virtio-stub.c index ddb592f..3c1bf17 100644 --- a/hw/virtio/virtio-stub.c +++ b/hw/virtio/virtio-stub.c@@ -17,3 +17,9 @@ VirtioStatus *qmp_x_debug_virtio_status(const char* path, Error **errp){ return qmp_virtio_unsupported(errp); } + +VirtQueueStatus *qmp_x_debug_virtio_queue_status(const char *path,+ uint16_t queue, Error **errp)+{ + return qmp_virtio_unsupported(errp); +} diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index 81a0ee8..ccd4371 100644 --- a/hw/virtio/virtio.c +++ b/hw/virtio/virtio.c@@ -3935,6 +3935,43 @@ static VirtIODevice *virtio_device_find(const char *path)return NULL; } +VirtQueueStatus *qmp_x_debug_virtio_queue_status(const char *path,+ uint16_t queue, Error **errp)+{ + VirtIODevice *vdev; + VirtQueueStatus *status; + + vdev = virtio_device_find(path); + if (vdev == NULL) { + error_setg(errp, "Path %s is not a VirtIO device", path); + return NULL; + } ++ if (queue >= VIRTIO_QUEUE_MAX || !virtio_queue_get_num(vdev, queue)) {+ error_setg(errp, "Invalid virtqueue number %d", queue); + return NULL; + } + + status = g_new0(VirtQueueStatus, 1);+ status->device_type = qapi_enum_parse(&VirtioType_lookup, vdev->name,+ VIRTIO_TYPE_UNKNOWN, NULL); + status->queue_index = vdev->vq[queue].queue_index; + status->inuse = vdev->vq[queue].inuse; + status->vring_num = vdev->vq[queue].vring.num; + status->vring_num_default = vdev->vq[queue].vring.num_default; + status->vring_align = vdev->vq[queue].vring.align; + status->vring_desc = vdev->vq[queue].vring.desc; + status->vring_avail = vdev->vq[queue].vring.avail; + status->vring_used = vdev->vq[queue].vring.used; + status->last_avail_idx = vdev->vq[queue].last_avail_idx;As mentioned in previous versions. We need add vhost support otherwise the value here is wrong.another value (whatever that might be)?You can query the vhost for those index. (vhost_get_vring_base())Same question for shadow_avail_idx below as well.It's an implementation specific. I think we can simply not show it if vhost is enabled.ThanksAh I see, thank you!So, it appears to me that it's not very easy to get the struct vhost_dev pointer from struct VirtIODevice to indicate whether or not vhost is active, e.g. there's no virtio class-independent way to get struct vhost_dev.I was thinking of adding an op/callback function to struct VirtioDeviceClass, e.g. bool has_vhost(VirtIODevice *vdev), and implement it for each virtio class (net, scsi, blk, etc.).For example, for virtio-net, maybe it'd be something like: bool has_vhost(VirtIODevice *vdev) { VirtIONet *n = VIRTIO_NET(vdev); NetClientState *nc = qemu_get_queue(n->nic); return nc->peer ? get_vhost_net(nc->peer) : false; }Also, for getting the last_avail_idx, I was also thinking of adding another op/callback to struct VirtioDeviceClass, e.g. unsigned int get_last_avail_idx(VirtIODevice *vdev, unsigned int vq_idx) that finds if vhost is active or not and either gets last_avail_idx from virtio directly or through vhost (e.g. vhost_dev->vhost_ops->vhost_get_vring_base()).I wanted to run this by you and get your opinion on this before I started implementing it in code. Let me know what you think about this.JonahJonah+ status->shadow_avail_idx = vdev->vq[queue].shadow_avail_idx;The shadow index is something that is implementation specific e.g in the case of vhost it's kind of meaningless.Thanks+ status->used_idx = vdev->vq[queue].used_idx; + status->signalled_used = vdev->vq[queue].signalled_used;+ status->signalled_used_valid = vdev->vq[queue].signalled_used_valid;+ + return status; +} + #define CONVERT_FEATURES(type, map) \ ({ \ type *list = NULL; \ diff --git a/qapi/virtio.json b/qapi/virtio.json index 78873cd..7007e0c 100644 --- a/qapi/virtio.json +++ b/qapi/virtio.json @@ -406,3 +406,105 @@ 'data': { 'path': 'str' }, 'returns': 'VirtioStatus' } + +## +# @VirtQueueStatus: +# +# Status of a VirtQueue +# +# @device-type: VirtIO device type +# +# @queue-index: VirtQueue queue_index +# +# @inuse: VirtQueue inuse +# +# @vring-num: VirtQueue vring.num +# +# @vring-num-default: VirtQueue vring.num_default +# +# @vring-align: VirtQueue vring.align +# +# @vring-desc: VirtQueue vring.desc +# +# @vring-avail: VirtQueue vring.avail +# +# @vring-used: VirtQueue vring.used +# +# @last-avail-idx: VirtQueue last_avail_idx +# +# @shadow-avail-idx: VirtQueue shadow_avail_idx +# +# @used-idx: VirtQueue used_idx +# +# @signalled-used: VirtQueue signalled_used +# +# @signalled-used-valid: VirtQueue signalled_used_valid +# +# Since: 6.1 +# +## + +{ 'struct': 'VirtQueueStatus', + 'data': { + 'device-type': 'VirtioType', + 'queue-index': 'uint16', + 'inuse': 'uint32', + 'vring-num': 'int', + 'vring-num-default': 'int', + 'vring-align': 'int', + 'vring-desc': 'uint64', + 'vring-avail': 'uint64', + 'vring-used': 'uint64', + 'last-avail-idx': 'uint16', + 'shadow-avail-idx': 'uint16', + 'used-idx': 'uint16', + 'signalled-used': 'uint16', + 'signalled-used-valid': 'uint16' + } +} + +## +# @x-debug-virtio-queue-status: +# +# Return the status of a given VirtQueue +# +# @path: QOBject path of the VirtIODevice +# +# @queue: queue number to examine +# +# Returns: Status of the VirtQueue +# +# Since: 6.1 +# +# Example: +# +# -> { "execute": "x-debug-virtio-queue-status", +# "arguments": {+# "path": "/machine/peripheral-anon/device[3]/virtio-backend",+# "queue": 0 +# } +# } +# <- { "return": { +# "signalled-used": 373, +# "inuse": 0, +# "vring-align": 4096, +# "vring-desc": 864411648, +# "signalled-used-valid": 0, +# "vring-num-default": 256, +# "vring-avail": 864415744, +# "queue-index": 0, +# "last-avail-idx": 373, +# "vring-used": 864416320, +# "used-idx": 373, +# "device-type": "virtio-net", +# "shadow-avail-idx": 619, +# "vring-num": 256 +# } +# } +# +## + +{ 'command': 'x-debug-virtio-queue-status', + 'data': { 'path': 'str', 'queue': 'uint16' }, + 'returns': 'VirtQueueStatus' +}