On 12/2/22 10:21, Markus Armbruster wrote:
Philippe Mathieu-Daudé<phi...@linaro.org> writes:
On 2/12/22 13:23, Jonah Palmer wrote:
On 11/30/22 11:16, Philippe Mathieu-Daudé wrote:
Hi,
On 11/8/22 14:24, Jonah Palmer wrote:
From: Laurent Vivier<lviv...@redhat.com>
This new command lists all the instances of VirtIODevices with
their canonical QOM path and name.
[Jonah: @virtio_list duplicates information that already exists in
the QOM composition tree. However, extracting necessary information
from this tree seems to be a bit convoluted.
Instead, we still create our own list of realized virtio devices
but use @qmp_qom_get with the device's canonical QOM path to confirm
that the device exists and is realized. If the device exists but
is actually not realized, then we remove it from our list (for
synchronicity to the QOM composition tree).
How could this happen?
Also, the QMP command @x-query-virtio is redundant as @qom-list
and @qom-get are sufficient to search '/machine/' for realized
virtio devices. However, @x-query-virtio is much more convenient
in listing realized virtio devices.]
Signed-off-by: Laurent Vivier<lviv...@redhat.com>
Signed-off-by: Jonah Palmer<jonah.pal...@oracle.com>
---
hw/virtio/meson.build | 2 ++
hw/virtio/virtio-stub.c | 14 ++++++++
hw/virtio/virtio.c | 44 ++++++++++++++++++++++++
include/hw/virtio/virtio.h | 1 +
qapi/meson.build | 1 +
qapi/qapi-schema.json | 1 +
qapi/virtio.json | 68 ++++++++++++++++++++++++++++++++++++++
tests/qtest/qmp-cmd-test.c | 1 +
8 files changed, 132 insertions(+)
create mode 100644 hw/virtio/virtio-stub.c
create mode 100644 qapi/virtio.json
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 5d607aeaa0..bdfa82e9c0 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -13,12 +13,18 @@
#include "qemu/osdep.h"
#include "qapi/error.h"
+#include "qapi/qmp/qdict.h"
+#include "qapi/qapi-commands-virtio.h"
+#include "qapi/qapi-commands-qom.h"
+#include "qapi/qapi-visit-virtio.h"
+#include "qapi/qmp/qjson.h"
#include "cpu.h"
#include "trace.h"
#include "qemu/error-report.h"
#include "qemu/log.h"
#include "qemu/main-loop.h"
#include "qemu/module.h"
+#include "qom/object_interfaces.h"
#include "hw/virtio/virtio.h"
#include "migration/qemu-file-types.h"
#include "qemu/atomic.h"
@@ -29,6 +35,9 @@
#include "sysemu/runstate.h"
#include "standard-headers/linux/virtio_ids.h"
+/* QAPI list of realized VirtIODevices */
+static QTAILQ_HEAD(, VirtIODevice) virtio_list;
+
/*
* The alignment to use between consumer and producer parts of vring.
* x86 pagesize again. This is the default, used by transports like PCI
@@ -3698,6 +3707,7 @@ static void virtio_device_realize(DeviceState *dev, Error
**errp)
vdev->listener.commit = virtio_memory_listener_commit;
vdev->listener.name = "virtio";
memory_listener_register(&vdev->listener, vdev->dma_as);
+ QTAILQ_INSERT_TAIL(&virtio_list, vdev, next);
}
static void virtio_device_unrealize(DeviceState *dev)
@@ -3712,6 +3722,7 @@ static void virtio_device_unrealize(DeviceState *dev)
vdc->unrealize(dev);
}
+ QTAILQ_REMOVE(&virtio_list, vdev, next);
g_free(vdev->bus_name);
vdev->bus_name = NULL;
}
@@ -3885,6 +3896,8 @@ static void virtio_device_class_init(ObjectClass *klass,
void *data)
vdc->stop_ioeventfd = virtio_device_stop_ioeventfd_impl;
vdc->legacy_features |= VIRTIO_LEGACY_FEATURES;
+
+ QTAILQ_INIT(&virtio_list);
}
bool virtio_device_ioeventfd_enabled(VirtIODevice *vdev)
@@ -3895,6 +3908,37 @@ bool virtio_device_ioeventfd_enabled(VirtIODevice *vdev)
return virtio_bus_ioeventfd_enabled(vbus);
}
+VirtioInfoList *qmp_x_query_virtio(Error **errp)
+{
+ VirtioInfoList *list = NULL;
+ VirtioInfoList *node;
+ VirtIODevice *vdev;
+
+ QTAILQ_FOREACH(vdev, &virtio_list, next) {
+ DeviceState *dev = DEVICE(vdev);
+ Error *err = NULL;
+ QObject *obj = qmp_qom_get(dev->canonical_path, "realized", &err);
+
+ if (err == NULL) {
+ GString *is_realized = qobject_to_json_pretty(obj, true);
+ /* virtio device is NOT realized, remove it from list */
Why not check dev->realized instead of calling qmp_qom_get() &
qobject_to_json_pretty()?
This check queries the QOM composition tree to check that the device actually
exists and is
realized. In other words, we just want to confirm with the QOM composition tree
for the device.
Again, how could this happen?
If @virtio_list isn't reliable, why have it in the first place?
Honestly, I'm not sure how this even could happen, since the @virtio_list is
managed at the realization
and unrealization of a virtio device. Given this, I do feel as though the list
is reliable, although
this might just benaïve of me to say. After giving this a second look, the @virtio_list is
only really needed to provide a nice list of all realized virtio devices
on the system, along with their full canonical paths. If the user can
find the canonical path of a virtio device by searching the QOM
composition tree, and assuming we can get a @VirtioDevice object (in
code) from this canonical path, then the rest of the QMP/HMP features of
these patches could be done by solely by searching the QOM composition
tree. However, I think having this list of realized virtio devices as a
subset of the QOM composition tree is worth its weight, since the user
no longer has to search the entire tree to find virtio devices and piece
together their canonical paths. Of course, if we're somehow able to
generate a similar list in code by searching the QOM composition tree,
then there would be no need for this @virtio_list. However, it's really
not clear how, or if, such a list could be generated by parsing the QOM
composition tree.
This was done to have some kind of synchronicity between @virtio_list and the
QOM composition
tree, since the list duplicates information that already exists in the tree.
This check was recommended in v10 and added in v11 of this patch series.
Thanks, I found Markus comments:
v10:
https://urldefense.com/v3/__https://lore.kernel.org/qemu-devel/87ee6ogbiw....@dusky.pond.sub.org/__;!!ACWV5N9M2RV99hQ!LqeLFhE8PtTTg_qKRuP9Kgz5pyTNZLhYeRzp4a2oS8c3D5W8-irZoBW0L_Lf1ozm3qYidYhuVrjxjsAw$
My recommendation there was to *delete* virtio_list and search the QOM
composition tree instead:
@virtio_list duplicates information that exists in the QOM composition
tree. It needs to stay in sync. You could search the composition tree
instead.
The QOM composition tree is the source of truth.
This above is about the command's implementation, and ...
v11:
https://urldefense.com/v3/__https://lore.kernel.org/qemu-devel/87ee4abtdu....@pond.sub.org/__;!!ACWV5N9M2RV99hQ!LqeLFhE8PtTTg_qKRuP9Kgz5pyTNZLhYeRzp4a2oS8c3D5W8-irZoBW0L_Lf1ozm3qYidYhuVmVCuHjV$
Having the justification from v11 in the code rather than the commit
description could help.
... this part is about why the command could be useful.
[...]