Re: [PATCH v6 0/6] hmp, qmp: Add some commands to introspect virtio devices
On 7/22/21 5:16 AM, Jason Wang wrote: 在 2021/7/21 下午4:53, Jonah Palmer 写道: Hi Jason. My apologies for the delayed response, several work-related things came up recently, but they're slowing down now so I'm turning my attention these patches to get taken care of. A few questions and comments below (and in other following patches): On 7/13/21 10:42 PM, Jason Wang wrote: 在 2021/7/12 下午6:35, Jonah Palmer 写道: Dump the information of the head element of the third queue of virtio-scsi: (qemu) virtio queue-element /machine/peripheral-anon/device[3]/virtio-backend 3 index: 122 ndescs: 3 descs: addr 0x7302d000 len 4096 (write), addr 0x3c951763 len 108 (write, next), addr 0x3c951728 len 51 (next) I think it would be nice if we can show driver area and device area as well here. Sure thing. And I apologize if it's obvious (I'm relatively new to virtio), but how can I expose the driver area? So the spec defines three parts: the device area, the driver area, and the descriptor area. And they are all located in the guest memory. I understand that virtio devices are part of the Qemu process, but I also thought that virtio drivers are in the guest's kernel, which I don't believe I can see into from Qemu (or, at least, it's not obvious to me). It works like how you access the descriptor ring (descriptor area). Thanks Oh, I see now! I didn't realize the device area is essentially the used ring and the driver area is the avail ring (at least for the split virtqueue model). I see this in the virtio spec now. Thank you! Jonah Thanks
Re: [PATCH v6 0/6] hmp, qmp: Add some commands to introspect virtio devices
在 2021/7/21 下午4:53, Jonah Palmer 写道: Hi Jason. My apologies for the delayed response, several work-related things came up recently, but they're slowing down now so I'm turning my attention these patches to get taken care of. A few questions and comments below (and in other following patches): On 7/13/21 10:42 PM, Jason Wang wrote: 在 2021/7/12 下午6:35, Jonah Palmer 写道: Dump the information of the head element of the third queue of virtio-scsi: (qemu) virtio queue-element /machine/peripheral-anon/device[3]/virtio-backend 3 index: 122 ndescs: 3 descs: addr 0x7302d000 len 4096 (write), addr 0x3c951763 len 108 (write, next), addr 0x3c951728 len 51 (next) I think it would be nice if we can show driver area and device area as well here. Sure thing. And I apologize if it's obvious (I'm relatively new to virtio), but how can I expose the driver area? So the spec defines three parts: the device area, the driver area, and the descriptor area. And they are all located in the guest memory. I understand that virtio devices are part of the Qemu process, but I also thought that virtio drivers are in the guest's kernel, which I don't believe I can see into from Qemu (or, at least, it's not obvious to me). It works like how you access the descriptor ring (descriptor area). Thanks Jonah Thanks
Re: [PATCH v6 0/6] hmp, qmp: Add some commands to introspect virtio devices
Hi Jason. My apologies for the delayed response, several work-related things came up recently, but they're slowing down now so I'm turning my attention these patches to get taken care of. A few questions and comments below (and in other following patches): On 7/13/21 10:42 PM, Jason Wang wrote: 在 2021/7/12 下午6:35, Jonah Palmer 写道: Dump the information of the head element of the third queue of virtio-scsi: (qemu) virtio queue-element /machine/peripheral-anon/device[3]/virtio-backend 3 index: 122 ndescs: 3 descs: addr 0x7302d000 len 4096 (write), addr 0x3c951763 len 108 (write, next), addr 0x3c951728 len 51 (next) I think it would be nice if we can show driver area and device area as well here. Sure thing. And I apologize if it's obvious (I'm relatively new to virtio), but how can I expose the driver area? I understand that virtio devices are part of the Qemu process, but I also thought that virtio drivers are in the guest's kernel, which I don't believe I can see into from Qemu (or, at least, it's not obvious to me). Jonah Thanks
Re: [PATCH v6 0/6] hmp, qmp: Add some commands to introspect virtio devices
在 2021/7/12 下午6:35, Jonah Palmer 写道: Dump the information of the head element of the third queue of virtio-scsi: (qemu) virtio queue-element /machine/peripheral-anon/device[3]/virtio-backend 3 index: 122 ndescs: 3 descs: addr 0x7302d000 len 4096 (write), addr 0x3c951763 len 108 (write, next), addr 0x3c951728 len 51 (next) I think it would be nice if we can show driver area and device area as well here. Thanks
Re: [PATCH v6 0/6] hmp,qmp: Add some commands to introspect virtio devices
On Mon, Jul 12, 2021 at 06:35:31AM -0400, Jonah Palmer wrote:
> This series introduces new QMP/HMP commands to dump the status of a
> virtio device at different levels.
>
> [Jonah: Rebasing previous patchset from March for Qemu 6.1
> (here:
> https://lore.kernel.org/qemu-devel/1616084984-11263-1-git-send-email-jonah.pal...@oracle.com/)
> from Laurent's original qmp/hmp virtio commands from last May
> (here:
> https://lore.kernel.org/qemu-devel/20200507134800.10837-1-lviv...@redhat.com/)
> which included updating Makefile to meson.build, adding all virtio/vhost
> types, and
> other minor patching (e.g. qmp_x_debug_query_virtio uses QAPI_LIST_PREPEND
> rather
> than open coding to iterate through list of virtio devices, see patch 1/6).
>
> Also, added new features (since Qemu 6.1) to virtio-gpu, virtio-net, and
> virtio-balloon. Lastly, added display for the virtio device name in a
> few of the qmp/hmp commands as well as relative indicies for vrings
> (see patches 4/6, 6/6).]
Acked-by: Michael S. Tsirkin
needs to be either merged or acked by HMP maintainer.
> 1. Main command
>
> HMP Only:
>
> virtio [subcommand]
>
> Example:
>
> List all sub-commands:
>
> (qemu) virtio
> virtio query -- List all available virtio devices
> virtio status path -- Display status of a given virtio device
> virtio queue-status path queue -- Display status of a given virtio
> queue
> virtio queue-element path queue [index] -- Display element of a given
> virtio queue
>
> 2. List available virtio deices in the machine
>
> HMP Form:
>
> virtio query
>
> Example:
>
> (qemu) virtio query
> /machine/peripheral-anon/device[2]/virtio-backend [virtio-scsi]
> /machine/peripheral-anon/device[1]/virtio-backend [virtio-net]
> /machine/peripheral-anon/device[0]/virtio-backend [virtio-serial]
>
> QMP Form:
>
> { 'command': 'x-debug-query-virtio', 'returns': ['VirtioInfo'] }
>
> Example:
>
> -> { "execute": "x-debug-query-virtio" }
> <- { "return": [
> {
> "path":
> "/machine/peripheral-anon/device[2]/virtio-backend",
> "type": "virtio-scsi"
> },
> {
> "path":
> "/machine/peripheral-anon/device[1]/virtio-backend",
> "type": "virtio-net"
> },
> {
> "path":
> "/machine/peripheral-anon/device[0]/virtio-backend",
> "type": "virtio-serial"
> }
> ]
> }
>
> 3. Display status of a given virtio device
>
> HMP Form:
>
> virtio status
>
> Example:
>
> (qemu) virtio status /machine/peripheral-anon/device[2]/virtio-backend
> /machine/peripheral-anon/device[2]/virtio-backend:
> Device Id: 8
> Guest features: event-idx, indirect-desc, version-1, change,
> hotplug
> Host features: event-idx, indirect-desc, bad-feature,
> version-1,
> any-layout, notify-on-empty, change, hotplug
> Backend features:
> Endianness: little
> VirtQueues: 4
>
> QMP Form:
>
> { 'command': 'x-debug-virtio-status',
> 'data': { 'path': 'str' },
> 'returns': 'VirtioStatus'
> }
>
> Example:
>
> -> { "execute": "x-debug-virtio-status"
> "arguments": {
> "path": "/machine/peripheral-anon/device[2]/virtio-backend"
> }
>}
> <- { "return": {
> "device-endian": "little",
> "device-id": 8,
> "backend-features": {
> "transport": [
> ],
> "type": "virtio-scsi",
> "features": [
> ]
> },
> "num-vqs": 4,
> "guest-features": {
> "transport": [
> "event-idx",
> "indirect-desc",
> "version-1"
> ],
> "type": "virtio-scsi",
> "features": [
> "change",
> "hotplug"
> ]
> },
> "host-features": {
> "transport": [
> "event-idx",
> "indirect-desc",
> "bad-feature",
> "version-1",
> "any-layout",
> "notify-on-empty"
> ],
> "type": "virtio-scsi",
> "features": [
> "change",
> "hotplug"
> ]
> }
>
[PATCH v6 0/6] hmp, qmp: Add some commands to introspect virtio devices
This series introduces new QMP/HMP commands to dump the status of a
virtio device at different levels.
[Jonah: Rebasing previous patchset from March for Qemu 6.1
(here:
https://lore.kernel.org/qemu-devel/1616084984-11263-1-git-send-email-jonah.pal...@oracle.com/)
from Laurent's original qmp/hmp virtio commands from last May
(here:
https://lore.kernel.org/qemu-devel/20200507134800.10837-1-lviv...@redhat.com/)
which included updating Makefile to meson.build, adding all virtio/vhost types,
and
other minor patching (e.g. qmp_x_debug_query_virtio uses QAPI_LIST_PREPEND
rather
than open coding to iterate through list of virtio devices, see patch 1/6).
Also, added new features (since Qemu 6.1) to virtio-gpu, virtio-net, and
virtio-balloon. Lastly, added display for the virtio device name in a
few of the qmp/hmp commands as well as relative indicies for vrings
(see patches 4/6, 6/6).]
1. Main command
HMP Only:
virtio [subcommand]
Example:
List all sub-commands:
(qemu) virtio
virtio query -- List all available virtio devices
virtio status path -- Display status of a given virtio device
virtio queue-status path queue -- Display status of a given virtio queue
virtio queue-element path queue [index] -- Display element of a given
virtio queue
2. List available virtio deices in the machine
HMP Form:
virtio query
Example:
(qemu) virtio query
/machine/peripheral-anon/device[2]/virtio-backend [virtio-scsi]
/machine/peripheral-anon/device[1]/virtio-backend [virtio-net]
/machine/peripheral-anon/device[0]/virtio-backend [virtio-serial]
QMP Form:
{ 'command': 'x-debug-query-virtio', 'returns': ['VirtioInfo'] }
Example:
-> { "execute": "x-debug-query-virtio" }
<- { "return": [
{
"path": "/machine/peripheral-anon/device[2]/virtio-backend",
"type": "virtio-scsi"
},
{
"path": "/machine/peripheral-anon/device[1]/virtio-backend",
"type": "virtio-net"
},
{
"path": "/machine/peripheral-anon/device[0]/virtio-backend",
"type": "virtio-serial"
}
]
}
3. Display status of a given virtio device
HMP Form:
virtio status
Example:
(qemu) virtio status /machine/peripheral-anon/device[2]/virtio-backend
/machine/peripheral-anon/device[2]/virtio-backend:
Device Id: 8
Guest features: event-idx, indirect-desc, version-1, change,
hotplug
Host features: event-idx, indirect-desc, bad-feature,
version-1,
any-layout, notify-on-empty, change, hotplug
Backend features:
Endianness: little
VirtQueues: 4
QMP Form:
{ 'command': 'x-debug-virtio-status',
'data': { 'path': 'str' },
'returns': 'VirtioStatus'
}
Example:
-> { "execute": "x-debug-virtio-status"
"arguments": {
"path": "/machine/peripheral-anon/device[2]/virtio-backend"
}
}
<- { "return": {
"device-endian": "little",
"device-id": 8,
"backend-features": {
"transport": [
],
"type": "virtio-scsi",
"features": [
]
},
"num-vqs": 4,
"guest-features": {
"transport": [
"event-idx",
"indirect-desc",
"version-1"
],
"type": "virtio-scsi",
"features": [
"change",
"hotplug"
]
},
"host-features": {
"transport": [
"event-idx",
"indirect-desc",
"bad-feature",
"version-1",
"any-layout",
"notify-on-empty"
],
"type": "virtio-scsi",
"features": [
"change",
"hotplug"
]
}
}
}
4. Display status of a given virtio queue
HMP Form:
virtio queue-status
Example:
(qemu) virtio queue-status
/machine/peripheral-anon/device[2]/virtio-backend 3
/machine/peripheral-anon/device[2]/virtio-backend:
device_type:virtio-scsi
index: 3
inuse: 0
last_avail_idx: 4174 (78 % 256)
