Hi
On Wed, May 3, 2023 at 12:21 PM Albert Esteve <aest...@redhat.com> wrote:
> This API manages objects (in this iteration,
> dmabuf fds) that can be shared along different
> virtio devices.
>
> The API allows the different devices to add,
> remove and/or retrieve the objects by simply
> invoking the public functions that reside in the
> virtio-dmabuf file.
>
> Signed-off-by: Albert Esteve <aest...@redhat.com>
> ---
> hw/display/meson.build | 1 +
> hw/display/virtio-dmabuf.c | 88 +++++++++++++++++++++++
> include/hw/virtio/virtio-dmabuf.h | 58 ++++++++++++++++
> tests/unit/meson.build | 1 +
> tests/unit/test-virtio-dmabuf.c | 112 ++++++++++++++++++++++++++++++
> 5 files changed, 260 insertions(+)
> create mode 100644 hw/display/virtio-dmabuf.c
> create mode 100644 include/hw/virtio/virtio-dmabuf.h
> create mode 100644 tests/unit/test-virtio-dmabuf.c
>
> diff --git a/hw/display/meson.build b/hw/display/meson.build
> index 17165bd536..62a27395c0 100644
> --- a/hw/display/meson.build
> +++ b/hw/display/meson.build
> @@ -37,6 +37,7 @@ softmmu_ss.add(when: 'CONFIG_MACFB', if_true:
> files('macfb.c'))
> softmmu_ss.add(when: 'CONFIG_NEXTCUBE', if_true: files('next-fb.c'))
>
> softmmu_ss.add(when: 'CONFIG_VGA', if_true: files('vga.c'))
> +softmmu_ss.add(when: 'CONFIG_VIRTIO', if_true: files('virtio-dmabuf.c'))
>
> if (config_all_devices.has_key('CONFIG_VGA_CIRRUS') or
> config_all_devices.has_key('CONFIG_VGA_PCI') or
> diff --git a/hw/display/virtio-dmabuf.c b/hw/display/virtio-dmabuf.c
> new file mode 100644
> index 0000000000..3db939a2e3
> --- /dev/null
> +++ b/hw/display/virtio-dmabuf.c
> @@ -0,0 +1,88 @@
> +/*
> + * Virtio Shared dma-buf
> + *
> + * Copyright Red Hat, Inc. 2023
> + *
> + * Authors:
> + * Albert Esteve <aest...@redhat.com>
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or
> later.
> + * See the COPYING file in the top-level directory.
> + */
> +
> +#include "hw/virtio/virtio-dmabuf.h"
> +
> +
> +#define UUID_TO_POINTER(i) \
> + ((gpointer) (g_intern_static_string(qemu_uuid_unparse_strdup((&i)))))
> +
>
This will leak.
> +
> +static GMutex lock;
> +static GHashTable *resource_uuids;
> +
>
Rather than having global variables, shouldn't we associate virtio
resources with the virtio bus instead?
> +
> +static bool virtio_add_resource(QemuUUID uuid, gpointer value)
> +{
> + gpointer struuid = UUID_TO_POINTER(uuid);
> + if (resource_uuids == NULL) {
> + resource_uuids = g_hash_table_new_full(NULL, NULL, NULL, g_free);
>
You create "resource_uuids" implicitly in 2 places, in 2 different ways.
Let's not do that, and have an explicit initialization step instead (it
might be with the virtio bus construction, if we move the code there)
+ } else if (g_hash_table_lookup(resource_uuids, struuid) != NULL) {
>
You could implement a hash_func and key_equal_func for QemuUUID instead.
> + return false;
> + }
> +
> + return g_hash_table_insert(resource_uuids, struuid, value);
> +}
> +
> +static gpointer virtio_lookup_resource(QemuUUID uuid)
> +{
> + if (resource_uuids == NULL) {
> + return NULL;
> + }
> +
> + return g_hash_table_lookup(resource_uuids, UUID_TO_POINTER(uuid));
> +}
> +
> +bool virtio_add_dmabuf(QemuUUID uuid, int udmabuf_fd)
> +{
> + bool result;
> + if (udmabuf_fd < 0) {
> + return false;
> + }
> + g_mutex_lock(&lock);
> + if (resource_uuids == NULL) {
> + resource_uuids = g_hash_table_new(NULL, NULL);
> + }
> + result = virtio_add_resource(uuid, GINT_TO_POINTER(udmabuf_fd));
> + g_mutex_unlock(&lock);
> +
> + return result;
> +}
> +
> +bool virtio_remove_resource(QemuUUID uuid)
> +{
> + bool result;
> + g_mutex_lock(&lock);
> + result = g_hash_table_remove(resource_uuids, UUID_TO_POINTER(uuid));
> + g_mutex_unlock(&lock);
> +
> + return result;
> +}
> +
> +int virtio_lookup_dmabuf(QemuUUID uuid)
> +{
> + g_mutex_lock(&lock);
> + gpointer lookup_res = virtio_lookup_resource(uuid);
> + g_mutex_unlock(&lock);
> + if (lookup_res == NULL) {
> + return -1;
> + }
> +
> + return GPOINTER_TO_INT(lookup_res);
> +}
> +
> +void virtio_free_resources(void)
> +{
> + g_hash_table_destroy(resource_uuids);
> + /* Reference count shall be 0 after the implicit unref on destroy */
> + resource_uuids = NULL;
> +}
> diff --git a/include/hw/virtio/virtio-dmabuf.h
> b/include/hw/virtio/virtio-dmabuf.h
> new file mode 100644
> index 0000000000..1c1c713128
> --- /dev/null
> +++ b/include/hw/virtio/virtio-dmabuf.h
> @@ -0,0 +1,58 @@
> +/*
> + * Virtio Shared dma-buf
> + *
> + * Copyright Red Hat, Inc. 2023
> + *
> + * Authors:
> + * Albert Esteve <aest...@redhat.com>
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2.
> + * See the COPYING file in the top-level directory.
> + */
> +
> +#ifndef VIRTIO_DMABUF_H
> +#define VIRTIO_DMABUF_H
> +
> +#include "qemu/osdep.h"
> +
> +#include <glib.h>
> +#include "qemu/uuid.h"
> +
> +/**
> + * virtio_add_dmabuf() - Add a new dma-buf resource to the lookup table
> + * @uuid: new resource's UUID
> + * @dmabuf_fd: the dma-buf descriptor that will be stored and shared with
> + * other virtio devices
>
The comment should be clear about fd ownership. In this case, it looks like
it's the caller's responsibility to properly handle its lifecycle.
> + *
> + * Note: @dmabuf_fd must be a valid (non-negative) file descriptor.
> + *
> + * Return: true if the UUID did not exist and the resource has been added,
> + * false if another resource with the same UUID already existed.
> + * Note that if it finds a repeated UUID, the resource is not inserted in
> + * the lookup table.
> + */
> +bool virtio_add_dmabuf(QemuUUID uuid, int dmabuf_fd);
> +
> +/**
> + * virtio_remove_resource() - Removes a resource from the lookup table
> + * @uuid: resource's UUID
> + *
> + * Return: true if the UUID has been found and removed from the lookup
> table.
> + */
> +bool virtio_remove_resource(QemuUUID uuid);
> +
> +/**
> + * virtio_lookup_dmabuf() - Looks for a dma-buf resource in the lookup
> table
> + * @uuid: resource's UUID
> + *
> + * Return: the dma-buf file descriptor integer, or -1 if the key is not
> found.
> + */
> +int virtio_lookup_dmabuf(QemuUUID uuid);
> +
> +/**
> + * virtio_free_resources() - Destroys all keys and values of the shared
> + * resources lookup table, and frees them
> + */
> +void virtio_free_resources(void);
>
If it's part of the virtio bus, we won't need to have an API for it, it
will be done as part of object destruction.
> +
> +#endif /* VIRTIO_DMABUF_H */
> diff --git a/tests/unit/meson.build b/tests/unit/meson.build
> index 3bc78d8660..eb2a1a8872 100644
> --- a/tests/unit/meson.build
> +++ b/tests/unit/meson.build
> @@ -50,6 +50,7 @@ tests = {
> 'test-qapi-util': [],
> 'test-interval-tree': [],
> 'test-xs-node': [qom],
> + 'test-virtio-dmabuf': [meson.project_source_root() /
> 'hw/display/virtio-dmabuf.c'],
> }
>
> if have_system or have_tools
> diff --git a/tests/unit/test-virtio-dmabuf.c
> b/tests/unit/test-virtio-dmabuf.c
> new file mode 100644
> index 0000000000..063830c91c
> --- /dev/null
> +++ b/tests/unit/test-virtio-dmabuf.c
> @@ -0,0 +1,112 @@
> +/*
> + * QEMU tests for shared dma-buf API
> + *
> + * Copyright (c) 2023 Red Hat, Inc.
> + *
> + * This library is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2.1 of the License, or (at your option) any later version.
> + *
> + * This library is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with this library; if not, see <
> http://www.gnu.org/licenses/>.
> + *
> + */
> +
> +#include "qemu/osdep.h"
> +#include "hw/virtio/virtio-dmabuf.h"
> +
> +
> +static void test_add_remove_resources(void)
> +{
> + QemuUUID uuid;
> + int i, dmabuf_fd;
> +
> + for (i = 0; i < 100; ++i) {
> + qemu_uuid_generate(&uuid);
> + dmabuf_fd = g_random_int_range(3, 500);
> + /* Add a new resource */
> + g_assert(virtio_add_dmabuf(uuid, dmabuf_fd));
> + g_assert_cmpint(virtio_lookup_dmabuf(uuid), ==, dmabuf_fd);
> + /* Remove the resource */
> + g_assert(virtio_remove_resource(uuid));
> + /* Resource is not found anymore */
> + g_assert_cmpint(virtio_lookup_dmabuf(uuid), ==, -1);
> + }
> +}
> +
> +static void test_remove_invalid_resource(void)
> +{
> + QemuUUID uuid;
> + int i;
> +
> + for (i = 0; i < 20; ++i) {
> + qemu_uuid_generate(&uuid);
> + g_assert_cmpint(virtio_lookup_dmabuf(uuid), ==, -1);
> + /* Removing a resource that does not exist returns false */
> + g_assert_false(virtio_remove_resource(uuid));
> + }
> +}
> +
> +static void test_add_invalid_resource(void)
> +{
> + QemuUUID uuid;
> + int i, dmabuf_fd = -2, alt_dmabuf = 2;
> +
> + for (i = 0; i < 20; ++i) {
> + qemu_uuid_generate(&uuid);
> + /* Add a new resource with invalid (negative) resource fd */
> + g_assert_false(virtio_add_dmabuf(uuid, dmabuf_fd));
> + /* Resource is not found */
> + g_assert_cmpint(virtio_lookup_dmabuf(uuid), ==, -1);
> + }
> +
> + for (i = 0; i < 20; ++i) {
> + /* Add a valid resource */
> + qemu_uuid_generate(&uuid);
> + dmabuf_fd = g_random_int_range(3, 500);
> + g_assert(virtio_add_dmabuf(uuid, dmabuf_fd));
> + g_assert_cmpint(virtio_lookup_dmabuf(uuid), ==, dmabuf_fd);
> + /* Add a new resource with repeated uuid returns false */
> + g_assert_false(virtio_add_dmabuf(uuid, alt_dmabuf));
> + /* The value for the uuid key is not replaced */
> + g_assert_cmpint(virtio_lookup_dmabuf(uuid), ==, dmabuf_fd);
> + }
> +}
> +
> +static void test_free_resources(void)
> +{
> + QemuUUID uuids[20];
> + int i, dmabuf_fd;
> +
> + for (i = 0; i < ARRAY_SIZE(uuids); ++i) {
> + qemu_uuid_generate(&uuids[i]);
> + dmabuf_fd = g_random_int_range(3, 500);
> + g_assert(virtio_add_dmabuf(uuids[i], dmabuf_fd));
> + g_assert_cmpint(virtio_lookup_dmabuf(uuids[i]), ==, dmabuf_fd);
> + }
> + virtio_free_resources();
> + for (i = 0; i < ARRAY_SIZE(uuids); ++i) {
> + /* None of the resources is found after free'd */
> + g_assert_cmpint(virtio_lookup_dmabuf(uuids[i]), ==, -1);
> + }
> +
> +}
> +
> +int main(int argc, char **argv)
> +{
> + g_test_init(&argc, &argv, NULL);
> + g_test_add_func("/virtio-dmabuf/add_rm_res",
> test_add_remove_resources);
> + g_test_add_func("/virtio-dmabuf/rm_invalid_res",
> + test_remove_invalid_resource);
> + g_test_add_func("/virtio-dmabuf/add_invalid_res",
> + test_add_invalid_resource);
> + g_test_add_func("/virtio-dmabuf/free_res", test_free_resources);
> +
> + return g_test_run();
> +}
> --
> 2.40.0
>
>
>
--
Marc-André Lureau
