On Thu, Feb 15, 2024 at 10:45 AM Albert Esteve <aest...@redhat.com> wrote:
>
>
> 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.
>
The problem is that current lock is a global static, and `QemuMutex` needs
to be
initialised by doing `qemu_mutex_init(&lock);`.
Maybe can be initialised at vhost-user.c by adding a public function?
>
>
>> > +
>> > + 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
>>
>>
