On Tue, Feb 6, 2024 at 12:11 AM Alex Bennée <alex.ben...@linaro.org> wrote:
> Albert Esteve <aest...@redhat.com> writes:
>
> > Ensure that we cleanup all virtio shared
> > resources when the vhost devices is cleaned
> > up (after a hot unplug, or a crash).
> >
> > To do so, we add a new function to the virtio_dmabuf
> > API called `virtio_dmabuf_vhost_cleanup`, which
> > loop through the table and removes all
> > resources owned by the vhost device parameter.
> >
> > Also, add a test to verify that the new
> > function in the API behaves as expected.
> >
> > Signed-off-by: Albert Esteve <aest...@redhat.com>
> > Acked-by: Stefan Hajnoczi <stefa...@redhat.com>
> > ---
> > hw/display/virtio-dmabuf.c | 22 +++++++++++++++++++++
> > hw/virtio/vhost.c | 3 +++
> > include/hw/virtio/virtio-dmabuf.h | 10 ++++++++++
> > tests/unit/test-virtio-dmabuf.c | 33 +++++++++++++++++++++++++++++++
> > 4 files changed, 68 insertions(+)
> >
> > diff --git a/hw/display/virtio-dmabuf.c b/hw/display/virtio-dmabuf.c
> > index 3dba4577ca..6688809777 100644
> > --- a/hw/display/virtio-dmabuf.c
> > +++ b/hw/display/virtio-dmabuf.c
> > @@ -136,6 +136,28 @@ SharedObjectType virtio_object_type(const QemuUUID
> *uuid)
> > return vso->type;
> > }
> >
> > +static bool virtio_dmabuf_resource_is_owned(gpointer key,
> > + gpointer value,
> > + gpointer dev)
> > +{
> > + VirtioSharedObject *vso;
> > +
> > + vso = (VirtioSharedObject *) value;
> > + return vso->type == TYPE_VHOST_DEV && vso->value == dev;
>
> It's a bit surprising to see vso->value being an anonymous gpointer
> rather than the proper type and a bit confusing between value and
> vso->value.
>
>
It is the signature required for this to be used with
`g_hash_table_foreach_remove`.
For the naming, the HashMap stores gpointers, that point to
`VirtioSharedObject`, and
these point to the underlying type (stored at `vso->value`). It may sound a
bit confusing,
but is a byproduct of the VirtioSharedObject indirection. Not sure which
names could be
more fit for this, but I'm open to change them.
> > +}
> > +
> > +int virtio_dmabuf_vhost_cleanup(struct vhost_dev *dev)
> > +{
> > + int num_removed;
> > +
> > + g_mutex_lock(&lock);
> > + num_removed = g_hash_table_foreach_remove(
> > + resource_uuids, (GHRFunc) virtio_dmabuf_resource_is_owned, dev);
> > + g_mutex_unlock(&lock);
>
> I'll note if we used a QemuMutex for the lock we could:
>
> - use WITH_QEMU_LOCK_GUARD(&lock) { }
> - enable QSP porfiling for the lock
>
>
Was not aware of these QemuMutex's. I wouldn't mind changing the mutex in
this
file in a different commit.
> > +
> > + return num_removed;
> > +}
> > +
> > void virtio_free_resources(void)
> > {
> > g_mutex_lock(&lock);
> > diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
> > index 2c9ac79468..c5622eac14 100644
> > --- a/hw/virtio/vhost.c
> > +++ b/hw/virtio/vhost.c
> > @@ -16,6 +16,7 @@
> > #include "qemu/osdep.h"
> > #include "qapi/error.h"
> > #include "hw/virtio/vhost.h"
> > +#include "hw/virtio/virtio-dmabuf.h"
> > #include "qemu/atomic.h"
> > #include "qemu/range.h"
> > #include "qemu/error-report.h"
> > @@ -1599,6 +1600,8 @@ void vhost_dev_cleanup(struct vhost_dev *hdev)
> > migrate_del_blocker(&hdev->migration_blocker);
> > g_free(hdev->mem);
> > g_free(hdev->mem_sections);
> > + /* free virtio shared objects */
> > + virtio_dmabuf_vhost_cleanup(hdev);
> > if (hdev->vhost_ops) {
> > hdev->vhost_ops->vhost_backend_cleanup(hdev);
> > }
> > diff --git a/include/hw/virtio/virtio-dmabuf.h
> b/include/hw/virtio/virtio-dmabuf.h
> > index 627c3b6db7..73f70fb482 100644
> > --- a/include/hw/virtio/virtio-dmabuf.h
> > +++ b/include/hw/virtio/virtio-dmabuf.h
> > @@ -91,6 +91,16 @@ struct vhost_dev *virtio_lookup_vhost_device(const
> QemuUUID *uuid);
> > */
> > SharedObjectType virtio_object_type(const QemuUUID *uuid);
> >
> > +/**
> > + * virtio_dmabuf_vhost_cleanup() - Destroys all entries of the shared
> > + * resources lookup table that are owned by the vhost backend
> > + * @dev: the pointer to the vhost device that owns the entries. Data is
> owned
> > + * by the called of the function.
> > + *
> > + * Return: the number of resource entries removed.
> > + */
> > +int virtio_dmabuf_vhost_cleanup(struct vhost_dev *dev);
> > +
> > /**
> > * virtio_free_resources() - Destroys all keys and values of the shared
> > * resources lookup table, and frees them
> > diff --git a/tests/unit/test-virtio-dmabuf.c
> b/tests/unit/test-virtio-dmabuf.c
> > index a45ec52f42..1c8123c2d2 100644
> > --- a/tests/unit/test-virtio-dmabuf.c
> > +++ b/tests/unit/test-virtio-dmabuf.c
> > @@ -103,6 +103,38 @@ static void test_add_invalid_resource(void)
> > }
> > }
> >
> > +static void test_cleanup_res(void)
> > +{
> > + QemuUUID uuids[20], uuid_alt;
> > + struct vhost_dev *dev = g_new0(struct vhost_dev, 1);
> > + struct vhost_dev *dev_alt = g_new0(struct vhost_dev, 1);
> > + int i, num_removed;
> > +
> > + for (i = 0; i < ARRAY_SIZE(uuids); ++i) {
> > + qemu_uuid_generate(&uuids[i]);
> > + virtio_add_vhost_device(&uuids[i], dev);
> > + /* vhost device is found */
> > + g_assert(virtio_lookup_vhost_device(&uuids[i]) != NULL);
> > + }
> > + qemu_uuid_generate(&uuid_alt);
> > + virtio_add_vhost_device(&uuid_alt, dev_alt);
> > + /* vhost device is found */
> > + g_assert(virtio_lookup_vhost_device(&uuid_alt) != NULL);
> > + /* cleanup all dev resources */
> > + num_removed = virtio_dmabuf_vhost_cleanup(dev);
> > + g_assert_cmpint(num_removed, ==, ARRAY_SIZE(uuids));
> > + for (i = 0; i < ARRAY_SIZE(uuids); ++i) {
> > + /* None of the dev resources is found after free'd */
> > + g_assert_cmpint(virtio_lookup_dmabuf(&uuids[i]), ==, -1);
> > + }
> > + /* uuid_alt is still in the hash table */
> > + g_assert(virtio_lookup_vhost_device(&uuid_alt) != NULL);
> > +
> > + virtio_free_resources();
> > + g_free(dev);
> > + g_free(dev_alt);
> > +}
> > +
> > static void test_free_resources(void)
> > {
> > QemuUUID uuids[20];
> > @@ -131,6 +163,7 @@ int main(int argc, char **argv)
> > test_remove_invalid_resource);
> > g_test_add_func("/virtio-dmabuf/add_invalid_res",
> > test_add_invalid_resource);
> > + g_test_add_func("/virtio-dmabuf/cleanup_dev", test_cleanup_res);
> > g_test_add_func("/virtio-dmabuf/free_res", test_free_resources);
> >
> > return g_test_run();
>
> --
> Alex Bennée
> Virtualisation Tech Lead @ Linaro
>
>
