| Message ID | 20210326054433.11762-2-dongli.zhang@oracle.com |
|---|---|
| State | New |
| Headers | show |
| Series | Add debug interface to kick/call on purpose | expand |
On Thu, Mar 25, 2021 at 10:44:28PM -0700, Dongli Zhang wrote: > The virtio device/driver (e.g., vhost-scsi or vhost-net) may hang due to > the loss of doorbell kick, e.g., > > https://lists.gnu.org/archive/html/qemu-devel/2018-12/msg01711.html > > ... or due to the loss of IRQ, e.g., as fixed by linux kernel commit > fe200ae48ef5 ("genirq: Mark polled irqs and defer the real handler"). > > This patch introduces a new debug interface 'DeviceEvent' to DeviceClass > to help narrow down if the issue is due to loss of irq/kick. So far the new > interface handles only two events: 'call' and 'kick'. Any device (e.g., > virtio/vhost or VFIO) may implement the interface (e.g., via eventfd, MSI-X > or legacy IRQ). > > The 'call' is to inject irq on purpose by admin for a specific device (e.g., > vhost-scsi) from QEMU/host to VM, while the 'kick' is to kick the doorbell > on purpose by admin at QEMU/host side for a specific device. > > Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com> [...] > diff --git a/include/monitor/hmp.h b/include/monitor/hmp.h > index 605d57287a..c7795d4ba5 100644 > --- a/include/monitor/hmp.h > +++ b/include/monitor/hmp.h > @@ -129,5 +129,6 @@ void hmp_info_replay(Monitor *mon, const QDict *qdict); > void hmp_replay_break(Monitor *mon, const QDict *qdict); > void hmp_replay_delete_break(Monitor *mon, const QDict *qdict); > void hmp_replay_seek(Monitor *mon, const QDict *qdict); > +void hmp_x_debug_device_event(Monitor *mon, const QDict *qdict); > > #endif > diff --git a/qapi/qdev.json b/qapi/qdev.json > index b83178220b..711c4a297a 100644 > --- a/qapi/qdev.json > +++ b/qapi/qdev.json > @@ -124,3 +124,33 @@ > ## > { 'event': 'DEVICE_DELETED', > 'data': { '*device': 'str', 'path': 'str' } } > + > +## > +# @x-debug-device-event: > +# > +# Generate device event for a specific device queue > +# > +# @dev: device path > +# > +# @event: event (e.g., kick or call) to trigger Any specific reason to not use an enum here? In addition to making the QAPI schema and documentation more descriptive, it would save you the work of manually defining the DEVICE_EVENT_* constants and implementing get_device_event(). > +# > +# @queue: queue id > +# > +# Returns: Nothing on success > +# > +# Since: 6.1 > +# > +# Notes: This is used to debug VM driver hang issue. The 'kick' event is to > +# send notification to QEMU/vhost while the 'call' event is to > +# interrupt VM on purpose. > +# > +# Example: > +# > +# -> { "execute": "x-debug-device_event", > +# "arguments": { "dev": "/machine/peripheral/vscsi0", "event": "kick", > +# "queue": 1 } } > +# <- { "return": {} } > +# > +## > +{ 'command': 'x-debug-device-event', > + 'data': {'dev': 'str', 'event': 'str', 'queue': 'int'} } [...]
On 4/7/21 6:40 AM, Eduardo Habkost wrote: > On Thu, Mar 25, 2021 at 10:44:28PM -0700, Dongli Zhang wrote: >> The virtio device/driver (e.g., vhost-scsi or vhost-net) may hang due to >> the loss of doorbell kick, e.g., >> >> https://urldefense.com/v3/__https://lists.gnu.org/archive/html/qemu-devel/2018-12/msg01711.html__;!!GqivPVa7Brio!NaqdV_o0gMJkUtVWaHyLRwKDa_8MsiuANAqEcM-Ooy4pYE3R1bwPmLdCTkE0gq6gywY$ >> >> ... or due to the loss of IRQ, e.g., as fixed by linux kernel commit >> fe200ae48ef5 ("genirq: Mark polled irqs and defer the real handler"). >> >> This patch introduces a new debug interface 'DeviceEvent' to DeviceClass >> to help narrow down if the issue is due to loss of irq/kick. So far the new >> interface handles only two events: 'call' and 'kick'. Any device (e.g., >> virtio/vhost or VFIO) may implement the interface (e.g., via eventfd, MSI-X >> or legacy IRQ). >> >> The 'call' is to inject irq on purpose by admin for a specific device (e.g., >> vhost-scsi) from QEMU/host to VM, while the 'kick' is to kick the doorbell >> on purpose by admin at QEMU/host side for a specific device. >> >> Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com> > [...] >> diff --git a/include/monitor/hmp.h b/include/monitor/hmp.h >> index 605d57287a..c7795d4ba5 100644 >> --- a/include/monitor/hmp.h >> +++ b/include/monitor/hmp.h >> @@ -129,5 +129,6 @@ void hmp_info_replay(Monitor *mon, const QDict *qdict); >> void hmp_replay_break(Monitor *mon, const QDict *qdict); >> void hmp_replay_delete_break(Monitor *mon, const QDict *qdict); >> void hmp_replay_seek(Monitor *mon, const QDict *qdict); >> +void hmp_x_debug_device_event(Monitor *mon, const QDict *qdict); >> >> #endif >> diff --git a/qapi/qdev.json b/qapi/qdev.json >> index b83178220b..711c4a297a 100644 >> --- a/qapi/qdev.json >> +++ b/qapi/qdev.json >> @@ -124,3 +124,33 @@ >> ## >> { 'event': 'DEVICE_DELETED', >> 'data': { '*device': 'str', 'path': 'str' } } >> + >> +## >> +# @x-debug-device-event: >> +# >> +# Generate device event for a specific device queue >> +# >> +# @dev: device path >> +# >> +# @event: event (e.g., kick or call) to trigger > > Any specific reason to not use an enum here? > > In addition to making the QAPI schema and documentation more > descriptive, it would save you the work of manually defining the > DEVICE_EVENT_* constants and implementing get_device_event(). Thank you very much for the suggestion! I will use enum in json file. Dongli Zhang > > >> +# >> +# @queue: queue id >> +# >> +# Returns: Nothing on success >> +# >> +# Since: 6.1 >> +# >> +# Notes: This is used to debug VM driver hang issue. The 'kick' event is to >> +# send notification to QEMU/vhost while the 'call' event is to >> +# interrupt VM on purpose. >> +# >> +# Example: >> +# >> +# -> { "execute": "x-debug-device_event", >> +# "arguments": { "dev": "/machine/peripheral/vscsi0", "event": "kick", >> +# "queue": 1 } } >> +# <- { "return": {} } >> +# >> +## >> +{ 'command': 'x-debug-device-event', >> + 'data': {'dev': 'str', 'event': 'str', 'queue': 'int'} } > [...] >
diff --git a/hmp-commands.hx b/hmp-commands.hx index 435c591a1c..d74b895fff 100644 --- a/hmp-commands.hx +++ b/hmp-commands.hx @@ -1725,3 +1725,17 @@ ERST .flags = "p", }, + { + .name = "x-debug-device-event", + .args_type = "dev:s,event:s,queue:l", + .params = "dev event queue", + .help = "generate device event for a specific device queue", + .cmd = hmp_x_debug_device_event, + .flags = "p", + }, + +SRST +``x-debug-device-event`` *dev* *event* *queue* + Generate device event *event* for specific *queue* of *dev* +ERST + diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h index bafc311bfa..1ea8bf23b9 100644 --- a/include/hw/qdev-core.h +++ b/include/hw/qdev-core.h @@ -29,9 +29,17 @@ typedef enum DeviceCategory { DEVICE_CATEGORY_MAX } DeviceCategory; +enum { + DEVICE_EVENT_CALL, + DEVICE_EVENT_KICK, + DEVICE_EVENT_MAX +}; + typedef void (*DeviceRealize)(DeviceState *dev, Error **errp); typedef void (*DeviceUnrealize)(DeviceState *dev); typedef void (*DeviceReset)(DeviceState *dev); +typedef void (*DeviceEvent)(DeviceState *dev, int event, int queue, + Error **errp); typedef void (*BusRealize)(BusState *bus, Error **errp); typedef void (*BusUnrealize)(BusState *bus); @@ -132,6 +140,7 @@ struct DeviceClass { DeviceReset reset; DeviceRealize realize; DeviceUnrealize unrealize; + DeviceEvent event; /* device state */ const VMStateDescription *vmsd; diff --git a/include/monitor/hmp.h b/include/monitor/hmp.h index 605d57287a..c7795d4ba5 100644 --- a/include/monitor/hmp.h +++ b/include/monitor/hmp.h @@ -129,5 +129,6 @@ void hmp_info_replay(Monitor *mon, const QDict *qdict); void hmp_replay_break(Monitor *mon, const QDict *qdict); void hmp_replay_delete_break(Monitor *mon, const QDict *qdict); void hmp_replay_seek(Monitor *mon, const QDict *qdict); +void hmp_x_debug_device_event(Monitor *mon, const QDict *qdict); #endif diff --git a/qapi/qdev.json b/qapi/qdev.json index b83178220b..711c4a297a 100644 --- a/qapi/qdev.json +++ b/qapi/qdev.json @@ -124,3 +124,33 @@ ## { 'event': 'DEVICE_DELETED', 'data': { '*device': 'str', 'path': 'str' } } + +## +# @x-debug-device-event: +# +# Generate device event for a specific device queue +# +# @dev: device path +# +# @event: event (e.g., kick or call) to trigger +# +# @queue: queue id +# +# Returns: Nothing on success +# +# Since: 6.1 +# +# Notes: This is used to debug VM driver hang issue. The 'kick' event is to +# send notification to QEMU/vhost while the 'call' event is to +# interrupt VM on purpose. +# +# Example: +# +# -> { "execute": "x-debug-device_event", +# "arguments": { "dev": "/machine/peripheral/vscsi0", "event": "kick", +# "queue": 1 } } +# <- { "return": {} } +# +## +{ 'command': 'x-debug-device-event', + 'data': {'dev': 'str', 'event': 'str', 'queue': 'int'} } diff --git a/softmmu/qdev-monitor.c b/softmmu/qdev-monitor.c index a9955b97a0..bca53111fb 100644 --- a/softmmu/qdev-monitor.c +++ b/softmmu/qdev-monitor.c @@ -924,6 +924,62 @@ void hmp_device_del(Monitor *mon, const QDict *qdict) hmp_handle_error(mon, err); } +static const char * const device_events[DEVICE_EVENT_MAX] = { + [DEVICE_EVENT_KICK] = "kick", + [DEVICE_EVENT_CALL] = "call" +}; + +static int get_device_event(const char *event) +{ + int evt; + + for (evt = 0; evt < ARRAY_SIZE(device_events); evt++) { + if (!strcmp(device_events[evt], event)) { + return evt; + } + } + + return -ENOENT; +} + +void qmp_x_debug_device_event(const char *dev, const char *event, + int64_t queue, Error **errp) +{ + DeviceState *device = find_device_state(dev, NULL); + DeviceClass *dc; + int evt; + + if (!device) { + error_setg(errp, "Device %s not found", dev); + return; + } + + dc = DEVICE_GET_CLASS(device); + if (!dc->event) { + error_setg(errp, "device_event is not supported"); + return; + } + + evt = get_device_event(event); + if (evt < 0) { + error_setg(errp, "Unsupported event %s", event); + return; + } + + dc->event(device, evt, queue, errp); +} + +void hmp_x_debug_device_event(Monitor *mon, const QDict *qdict) +{ + const char *dev = qdict_get_str(qdict, "dev"); + const char *event = qdict_get_str(qdict, "event"); + int queue = qdict_get_try_int(qdict, "queue", -1); + Error *err = NULL; + + qmp_x_debug_device_event(dev, event, queue, &err); + hmp_handle_error(mon, err); +} + BlockBackend *blk_by_qdev_id(const char *id, Error **errp) { DeviceState *dev;
The virtio device/driver (e.g., vhost-scsi or vhost-net) may hang due to the loss of doorbell kick, e.g., https://lists.gnu.org/archive/html/qemu-devel/2018-12/msg01711.html ... or due to the loss of IRQ, e.g., as fixed by linux kernel commit fe200ae48ef5 ("genirq: Mark polled irqs and defer the real handler"). This patch introduces a new debug interface 'DeviceEvent' to DeviceClass to help narrow down if the issue is due to loss of irq/kick. So far the new interface handles only two events: 'call' and 'kick'. Any device (e.g., virtio/vhost or VFIO) may implement the interface (e.g., via eventfd, MSI-X or legacy IRQ). The 'call' is to inject irq on purpose by admin for a specific device (e.g., vhost-scsi) from QEMU/host to VM, while the 'kick' is to kick the doorbell on purpose by admin at QEMU/host side for a specific device. Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com> --- hmp-commands.hx | 14 +++++++++++ include/hw/qdev-core.h | 9 +++++++ include/monitor/hmp.h | 1 + qapi/qdev.json | 30 ++++++++++++++++++++++ softmmu/qdev-monitor.c | 56 ++++++++++++++++++++++++++++++++++++++++++ 5 files changed, 110 insertions(+)