| Message ID | 20200402100302.833267-1-lvivier@redhat.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | hmp,qmp: Add some commands to introspect virtio devices | expand |
Hi On Thu, Apr 2, 2020 at 12:03 PM Laurent Vivier <lvivier@redhat.com> wrote: > > This series introduces new QMP/HMP commands to dump the status > of a a virtio device at different levels. Looks nice, but my feeling is that we are growing qemu with debugging facilities in general with HMP/QMP. If this is only for debugging purposes, why don't we compile it only when --enable-debug? A guest that would need to be debugged could have its state loaded in a debug version of qemu. Alternatively, I think most of the data you provide here could probably be introspected via gdb scripts. Just some thoughts > > 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 devices in the machine > > HMP Form: > > virtio query > > Example: > > (qemu) virtio query > /machine/peripheral-anon/device[3]/virtio-backend [virtio-net] > /machine/peripheral-anon/device[1]/virtio-backend [virtio-serial] > /machine/peripheral-anon/device[0]/virtio-backend [virtio-blk] > > QMP Form: > > { 'command': 'query-virtio', 'returns': ['VirtioInfo'] } > > Example: > > -> { "execute": "query-virtio" } > <- { "return": [ > { > "path": "/machine/peripheral-anon/device[3]/virtio-backend", > "type": "virtio-net" > }, > { > "path": "/machine/peripheral-anon/device[1]/virtio-backend", > "type": "virtio-serial" > }, > { > "path": "/machine/peripheral-anon/device[0]/virtio-backend", > "type": "virtio-blk" > } > ] > } > > 3. Display status of a given virtio device > > HMP Form: > > virtio status <path> > > Example: > > (qemu) virtio status /machine/peripheral-anon/device[3]/virtio-backend > /machine/peripheral-anon/device[3]/virtio-backend: > Device Id: 1 > Guest features: 0x0000000130afffa7 > Host features: 0x0000000179bfffe7 > Backend features: 0x0000000000000000 > Endianness: little > VirtQueues: 3 > > QMP Form: > > { 'command': 'virtio-status', > 'data': { 'path': 'str' }, > 'returns': 'VirtioStatus' > } > > Example: > > -> { "execute": "virtio-status", > "arguments": { > "path": "/machine/peripheral-anon/device[3]/virtio-backend" > } > } > <- { "return": { > "backend_features": 0, > "guest_features": 5111807911, > "num_vqs": 3, > "host_features": 6337593319, > "device_endian": "little", > "device_id": 1 > } > } > > 4. Display status of a given virtio queue > > HMP Form: > > virtio queue-status <path> <queue> > > Example: > > (qemu) virtio queue-status /machine/peripheral-anon/device[3]/virtio-backend 0 > /machine/peripheral-anon/device[3]/virtio-backend: > index: 0 > inuse: 0 > last_avail_idx: 61 > shadow_avail_idx: 292 > signalled_used: 61 > signalled_used_valid: 1 > VRing: > num: 256 > num_default: 256 > align: 4096 > desc: 0x000000006c352000 > avail: 0x000000006c353000 > used: 0x000000006c353240 > > QMP Form: > > { 'command': 'virtio-queue-status', > 'data': { 'path': 'str', 'queue': 'uint16' }, > 'returns': 'VirtQueueStatus' > } > > Example: > > -> { "execute": "virtio-queue-status", > "arguments": { > "path": "/machine/peripheral-anon/device[3]/virtio-backend", > "queue": 0 > } > } > <- { "return": { > "signalled_used": 373, > "inuse": 0, > "vring_desc": 864411648, > "vring_num_default": 256, > "signalled_used_valid": 1, > "vring_avail": 864415744, > "last_avail_idx": 373, > "queue_index": 0, > "vring_used": 864416320, > "shadow_avail_idx": 619, > "used_idx": 373, > "vring_num": 256, > "vring_align": 4096 > } > } > > 5. Display element of a given virtio queue > > HMP Form: > > virtio queue-element <path> <queue> [index] > > Example: > > Dump the information of the head element of the first queue of > the first virtio device:: > > (qemu) virtio queue-element/machine/peripheral-anon/device[3]/virtio-backend 0 > index: 67 > ndescs: 1 > descs: addr 0x6fe69800 len 1536 (write-only) > > (qemu) xp/128bx 0x6fe69800 > 000000006fe69800: 0x02 0x00 0x00 0x00 0x00 0x00 0x00 0x00 > 000000006fe69808: 0x00 0x00 0x01 0x00 0x52 0x54 0x00 0x12 > 000000006fe69810: 0x34 0x56 0x52 0x54 0x00 0x09 0x51 0xde > 000000006fe69818: 0x08 0x00 0x45 0x00 0x00 0x4c 0x8f 0x32 > > device[3] is a virtio-net device and we can see in the element buffer the > MAC address of the card:: > > [root@localhost ~]# ip link show ens4 > 2: ens4: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP m0 > link/ether 52:54:00:12:34:56 brd ff:ff:ff:ff:ff:ff > > and the MAC address of the gateway:: > > [root@localhost ~]# arp -a > _gateway (192.168.122.1) at 52:54:00:09:51:de [ether] on ens4 > > QMP Form: > > { 'command': 'virtio-queue-element', > 'data': { 'path': 'str', 'queue': 'uint16', '*index': 'uint16' }, > 'returns': 'VirtioQueueElement' > } > > 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 } > ] > } > } > > Laurent Vivier (5): > qmp: add QMP command query-virtio > qmp: add QMP command virtio-status > qmp: add QMP command virtio-queue-status > qmp: add QMP command virtio-queue-element > hmp: add virtio commands > > Makefile | 2 +- > Makefile.target | 7 +- > docs/system/monitor.rst | 2 + > hmp-commands-virtio.hx | 148 ++++++++++++++++++ > hmp-commands.hx | 10 ++ > hw/virtio/Makefile.objs | 2 + > hw/virtio/virtio-stub.c | 32 ++++ > hw/virtio/virtio.c | 313 +++++++++++++++++++++++++++++++++++++ > include/hw/virtio/virtio.h | 1 + > include/monitor/hmp.h | 4 + > monitor/misc.c | 17 ++ > qapi/Makefile.objs | 2 +- > qapi/qapi-schema.json | 1 + > qapi/virtio.json | 302 +++++++++++++++++++++++++++++++++++ > tests/qtest/qmp-cmd-test.c | 1 + > 15 files changed, 840 insertions(+), 4 deletions(-) > create mode 100644 hmp-commands-virtio.hx > create mode 100644 hw/virtio/virtio-stub.c > create mode 100644 qapi/virtio.json > > -- > 2.25.1 > >
* Marc-André Lureau (marcandre.lureau@gmail.com) wrote: > Hi > > On Thu, Apr 2, 2020 at 12:03 PM Laurent Vivier <lvivier@redhat.com> wrote: > > > > This series introduces new QMP/HMP commands to dump the status > > of a a virtio device at different levels. > > Looks nice, but my feeling is that we are growing qemu with debugging > facilities in general with HMP/QMP. > > If this is only for debugging purposes, why don't we compile it only > when --enable-debug? > > A guest that would need to be debugged could have its state loaded in > a debug version of qemu. > > Alternatively, I think most of the data you provide here could > probably be introspected via gdb scripts. > > Just some thoughts I kind of agree, but virtio is bread-and-butter, so having it available all the time isn't a bad idea; however having said that hte same argument would be for why having gdb scripts to examine your virtio queues would be useful if you're dealing with a core. Dave > > > > > 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 devices in the machine > > > > HMP Form: > > > > virtio query > > > > Example: > > > > (qemu) virtio query > > /machine/peripheral-anon/device[3]/virtio-backend [virtio-net] > > /machine/peripheral-anon/device[1]/virtio-backend [virtio-serial] > > /machine/peripheral-anon/device[0]/virtio-backend [virtio-blk] > > > > QMP Form: > > > > { 'command': 'query-virtio', 'returns': ['VirtioInfo'] } > > > > Example: > > > > -> { "execute": "query-virtio" } > > <- { "return": [ > > { > > "path": "/machine/peripheral-anon/device[3]/virtio-backend", > > "type": "virtio-net" > > }, > > { > > "path": "/machine/peripheral-anon/device[1]/virtio-backend", > > "type": "virtio-serial" > > }, > > { > > "path": "/machine/peripheral-anon/device[0]/virtio-backend", > > "type": "virtio-blk" > > } > > ] > > } > > > > 3. Display status of a given virtio device > > > > HMP Form: > > > > virtio status <path> > > > > Example: > > > > (qemu) virtio status /machine/peripheral-anon/device[3]/virtio-backend > > /machine/peripheral-anon/device[3]/virtio-backend: > > Device Id: 1 > > Guest features: 0x0000000130afffa7 > > Host features: 0x0000000179bfffe7 > > Backend features: 0x0000000000000000 > > Endianness: little > > VirtQueues: 3 > > > > QMP Form: > > > > { 'command': 'virtio-status', > > 'data': { 'path': 'str' }, > > 'returns': 'VirtioStatus' > > } > > > > Example: > > > > -> { "execute": "virtio-status", > > "arguments": { > > "path": "/machine/peripheral-anon/device[3]/virtio-backend" > > } > > } > > <- { "return": { > > "backend_features": 0, > > "guest_features": 5111807911, > > "num_vqs": 3, > > "host_features": 6337593319, > > "device_endian": "little", > > "device_id": 1 > > } > > } > > > > 4. Display status of a given virtio queue > > > > HMP Form: > > > > virtio queue-status <path> <queue> > > > > Example: > > > > (qemu) virtio queue-status /machine/peripheral-anon/device[3]/virtio-backend 0 > > /machine/peripheral-anon/device[3]/virtio-backend: > > index: 0 > > inuse: 0 > > last_avail_idx: 61 > > shadow_avail_idx: 292 > > signalled_used: 61 > > signalled_used_valid: 1 > > VRing: > > num: 256 > > num_default: 256 > > align: 4096 > > desc: 0x000000006c352000 > > avail: 0x000000006c353000 > > used: 0x000000006c353240 > > > > QMP Form: > > > > { 'command': 'virtio-queue-status', > > 'data': { 'path': 'str', 'queue': 'uint16' }, > > 'returns': 'VirtQueueStatus' > > } > > > > Example: > > > > -> { "execute": "virtio-queue-status", > > "arguments": { > > "path": "/machine/peripheral-anon/device[3]/virtio-backend", > > "queue": 0 > > } > > } > > <- { "return": { > > "signalled_used": 373, > > "inuse": 0, > > "vring_desc": 864411648, > > "vring_num_default": 256, > > "signalled_used_valid": 1, > > "vring_avail": 864415744, > > "last_avail_idx": 373, > > "queue_index": 0, > > "vring_used": 864416320, > > "shadow_avail_idx": 619, > > "used_idx": 373, > > "vring_num": 256, > > "vring_align": 4096 > > } > > } > > > > 5. Display element of a given virtio queue > > > > HMP Form: > > > > virtio queue-element <path> <queue> [index] > > > > Example: > > > > Dump the information of the head element of the first queue of > > the first virtio device:: > > > > (qemu) virtio queue-element/machine/peripheral-anon/device[3]/virtio-backend 0 > > index: 67 > > ndescs: 1 > > descs: addr 0x6fe69800 len 1536 (write-only) > > > > (qemu) xp/128bx 0x6fe69800 > > 000000006fe69800: 0x02 0x00 0x00 0x00 0x00 0x00 0x00 0x00 > > 000000006fe69808: 0x00 0x00 0x01 0x00 0x52 0x54 0x00 0x12 > > 000000006fe69810: 0x34 0x56 0x52 0x54 0x00 0x09 0x51 0xde > > 000000006fe69818: 0x08 0x00 0x45 0x00 0x00 0x4c 0x8f 0x32 > > > > device[3] is a virtio-net device and we can see in the element buffer the > > MAC address of the card:: > > > > [root@localhost ~]# ip link show ens4 > > 2: ens4: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP m0 > > link/ether 52:54:00:12:34:56 brd ff:ff:ff:ff:ff:ff > > > > and the MAC address of the gateway:: > > > > [root@localhost ~]# arp -a > > _gateway (192.168.122.1) at 52:54:00:09:51:de [ether] on ens4 > > > > QMP Form: > > > > { 'command': 'virtio-queue-element', > > 'data': { 'path': 'str', 'queue': 'uint16', '*index': 'uint16' }, > > 'returns': 'VirtioQueueElement' > > } > > > > 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 } > > ] > > } > > } > > > > Laurent Vivier (5): > > qmp: add QMP command query-virtio > > qmp: add QMP command virtio-status > > qmp: add QMP command virtio-queue-status > > qmp: add QMP command virtio-queue-element > > hmp: add virtio commands > > > > Makefile | 2 +- > > Makefile.target | 7 +- > > docs/system/monitor.rst | 2 + > > hmp-commands-virtio.hx | 148 ++++++++++++++++++ > > hmp-commands.hx | 10 ++ > > hw/virtio/Makefile.objs | 2 + > > hw/virtio/virtio-stub.c | 32 ++++ > > hw/virtio/virtio.c | 313 +++++++++++++++++++++++++++++++++++++ > > include/hw/virtio/virtio.h | 1 + > > include/monitor/hmp.h | 4 + > > monitor/misc.c | 17 ++ > > qapi/Makefile.objs | 2 +- > > qapi/qapi-schema.json | 1 + > > qapi/virtio.json | 302 +++++++++++++++++++++++++++++++++++ > > tests/qtest/qmp-cmd-test.c | 1 + > > 15 files changed, 840 insertions(+), 4 deletions(-) > > create mode 100644 hmp-commands-virtio.hx > > create mode 100644 hw/virtio/virtio-stub.c > > create mode 100644 qapi/virtio.json > > > > -- > > 2.25.1 > > > > > > > -- > Marc-André Lureau > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
This series introduces new QMP/HMP commands to dump the status of a a virtio device at different levels. 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 devices in the machine HMP Form: virtio query Example: (qemu) virtio query /machine/peripheral-anon/device[3]/virtio-backend [virtio-net] /machine/peripheral-anon/device[1]/virtio-backend [virtio-serial] /machine/peripheral-anon/device[0]/virtio-backend [virtio-blk] QMP Form: { 'command': 'query-virtio', 'returns': ['VirtioInfo'] } Example: -> { "execute": "query-virtio" } <- { "return": [ { "path": "/machine/peripheral-anon/device[3]/virtio-backend", "type": "virtio-net" }, { "path": "/machine/peripheral-anon/device[1]/virtio-backend", "type": "virtio-serial" }, { "path": "/machine/peripheral-anon/device[0]/virtio-backend", "type": "virtio-blk" } ] } 3. Display status of a given virtio device HMP Form: virtio status <path> Example: (qemu) virtio status /machine/peripheral-anon/device[3]/virtio-backend /machine/peripheral-anon/device[3]/virtio-backend: Device Id: 1 Guest features: 0x0000000130afffa7 Host features: 0x0000000179bfffe7 Backend features: 0x0000000000000000 Endianness: little VirtQueues: 3 QMP Form: { 'command': 'virtio-status', 'data': { 'path': 'str' }, 'returns': 'VirtioStatus' } Example: -> { "execute": "virtio-status", "arguments": { "path": "/machine/peripheral-anon/device[3]/virtio-backend" } } <- { "return": { "backend_features": 0, "guest_features": 5111807911, "num_vqs": 3, "host_features": 6337593319, "device_endian": "little", "device_id": 1 } } 4. Display status of a given virtio queue HMP Form: virtio queue-status <path> <queue> Example: (qemu) virtio queue-status /machine/peripheral-anon/device[3]/virtio-backend 0 /machine/peripheral-anon/device[3]/virtio-backend: index: 0 inuse: 0 last_avail_idx: 61 shadow_avail_idx: 292 signalled_used: 61 signalled_used_valid: 1 VRing: num: 256 num_default: 256 align: 4096 desc: 0x000000006c352000 avail: 0x000000006c353000 used: 0x000000006c353240 QMP Form: { 'command': 'virtio-queue-status', 'data': { 'path': 'str', 'queue': 'uint16' }, 'returns': 'VirtQueueStatus' } Example: -> { "execute": "virtio-queue-status", "arguments": { "path": "/machine/peripheral-anon/device[3]/virtio-backend", "queue": 0 } } <- { "return": { "signalled_used": 373, "inuse": 0, "vring_desc": 864411648, "vring_num_default": 256, "signalled_used_valid": 1, "vring_avail": 864415744, "last_avail_idx": 373, "queue_index": 0, "vring_used": 864416320, "shadow_avail_idx": 619, "used_idx": 373, "vring_num": 256, "vring_align": 4096 } } 5. Display element of a given virtio queue HMP Form: virtio queue-element <path> <queue> [index] Example: Dump the information of the head element of the first queue of the first virtio device:: (qemu) virtio queue-element/machine/peripheral-anon/device[3]/virtio-backend 0 index: 67 ndescs: 1 descs: addr 0x6fe69800 len 1536 (write-only) (qemu) xp/128bx 0x6fe69800 000000006fe69800: 0x02 0x00 0x00 0x00 0x00 0x00 0x00 0x00 000000006fe69808: 0x00 0x00 0x01 0x00 0x52 0x54 0x00 0x12 000000006fe69810: 0x34 0x56 0x52 0x54 0x00 0x09 0x51 0xde 000000006fe69818: 0x08 0x00 0x45 0x00 0x00 0x4c 0x8f 0x32 device[3] is a virtio-net device and we can see in the element buffer the MAC address of the card:: [root@localhost ~]# ip link show ens4 2: ens4: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP m0 link/ether 52:54:00:12:34:56 brd ff:ff:ff:ff:ff:ff and the MAC address of the gateway:: [root@localhost ~]# arp -a _gateway (192.168.122.1) at 52:54:00:09:51:de [ether] on ens4 QMP Form: { 'command': 'virtio-queue-element', 'data': { 'path': 'str', 'queue': 'uint16', '*index': 'uint16' }, 'returns': 'VirtioQueueElement' } 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 } ] } } Laurent Vivier (5): qmp: add QMP command query-virtio qmp: add QMP command virtio-status qmp: add QMP command virtio-queue-status qmp: add QMP command virtio-queue-element hmp: add virtio commands Makefile | 2 +- Makefile.target | 7 +- docs/system/monitor.rst | 2 + hmp-commands-virtio.hx | 148 ++++++++++++++++++ hmp-commands.hx | 10 ++ hw/virtio/Makefile.objs | 2 + hw/virtio/virtio-stub.c | 32 ++++ hw/virtio/virtio.c | 313 +++++++++++++++++++++++++++++++++++++ include/hw/virtio/virtio.h | 1 + include/monitor/hmp.h | 4 + monitor/misc.c | 17 ++ qapi/Makefile.objs | 2 +- qapi/qapi-schema.json | 1 + qapi/virtio.json | 302 +++++++++++++++++++++++++++++++++++ tests/qtest/qmp-cmd-test.c | 1 + 15 files changed, 840 insertions(+), 4 deletions(-) create mode 100644 hmp-commands-virtio.hx create mode 100644 hw/virtio/virtio-stub.c create mode 100644 qapi/virtio.json