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[PATCH 1/6] qdev: introduce qapi/hmp command for kick/call event
From: |
Dongli Zhang |
Subject: |
[PATCH 1/6] qdev: introduce qapi/hmp command for kick/call event |
Date: |
Thu, 25 Mar 2021 22:44:28 -0700 |
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(+)
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;
--
2.17.1
- [PATCH 0/6] Add debug interface to kick/call on purpose, Dongli Zhang, 2021/03/26
- [PATCH 6/6] virtio-net-pci: implement device event interface for kick/call, Dongli Zhang, 2021/03/26
- [PATCH 2/6] virtio: introduce helper function for kick/call device event, Dongli Zhang, 2021/03/26
- [PATCH 4/6] virtio-scsi-pci: implement device event interface for kick/call, Dongli Zhang, 2021/03/26
- [PATCH 3/6] virtio-blk-pci: implement device event interface for kick/call, Dongli Zhang, 2021/03/26
- [PATCH 1/6] qdev: introduce qapi/hmp command for kick/call event,
Dongli Zhang <=
- [PATCH 5/6] vhost-scsi-pci: implement device event interface for kick/call, Dongli Zhang, 2021/03/26
- Re: [PATCH 0/6] Add debug interface to kick/call on purpose, Jason Wang, 2021/03/26