On Thu, Jun 22, 2023 at 10:19 PM Marc-André Lureau <
marcandre.lur...@gmail.com> wrote:
> Hi
>
> On Wed, May 24, 2023 at 11:13 AM Albert Esteve <aest...@redhat.com> wrote:
>
>> Add new vhost-user protocol message
>> `VHOST_USER_BACKEND_SHARED_OBJECT`. This new
>> message is sent from vhost-user back-ends
>> to interact with the virtio-dmabuf table
>> in order to add, remove, or lookup for
>> virtio dma-buf shared objects.
>>
>> The action taken in the front-end depends
>> on the type stored in the payload struct.
>>
>> In the libvhost-user library add helper
>> functions to allow sending messages to
>> interact with the virtio shared objects
>> hash table.
>>
>> Signed-off-by: Albert Esteve <aest...@redhat.com>
>> ---
>> docs/interop/vhost-user.rst | 15 ++++
>> hw/virtio/vhost-user.c | 68 ++++++++++++++++++
>> subprojects/libvhost-user/libvhost-user.c | 88 +++++++++++++++++++++++
>> subprojects/libvhost-user/libvhost-user.h | 56 +++++++++++++++
>> 4 files changed, 227 insertions(+)
>>
>> diff --git a/docs/interop/vhost-user.rst b/docs/interop/vhost-user.rst
>> index 5a070adbc1..d3d8db41e5 100644
>> --- a/docs/interop/vhost-user.rst
>> +++ b/docs/interop/vhost-user.rst
>> @@ -1528,6 +1528,21 @@ is sent by the front-end.
>>
>> The state.num field is currently reserved and must be set to 0.
>>
>> +``VHOST_USER_BACKEND_SHARED_OBJECT``
>> + :id: 6
>> + :equivalent ioctl: N/A
>> + :request payload: ``struct VhostUserShared``
>> + :reply payload: ``struct VhostUserShared`` (only for ``LOOKUP``
>> requests)
>>
>
> only for LOOKUP, ahah...
>
I wasn't sure how to highlight that the reply was not required in all
cases...
>
>
>> +
>> + Backends that need to interact with the virtio-dmabuf shared table API
>> + can send this message. The operation is determined by the ``type``
>> member
>> + of the payload struct. The valid values for the operation type are
>> + ``VHOST_SHARED_OBJECT_*`` members, i.e., ``ADD``, ``LOOKUP``, and
>> ``REMOVE``.
>>
>
> ...why not use specific messages instead of this extra "type"?
>
I wouldn't mind having specific messages for each type.
I initially opted for having it one message to avoid having the code that
handles the
message scattered. The logic of each operation is simple and this way we
have a single
handler method for all of them.
Also, there are currently only a few slave requests available, so adding 3
new requests felt
like a higher "overhead".
But as I said, I don't have a strong opinion. Should I change it?
>
>
>
>> + ``LOOKUP`` operations require the ``VHOST_USER_NEED_REPLY_MASK`` flag
>> to be
>> + set by the back-end, and the front-end will then send the dma-buf fd as
>> + a response if the UUID matches an object in the table, or a negative
>> value
>> + otherwise.
>>
>
> This new message(s) should be initially negotiated with a protocol feature
> flag.
>
Ok. Similar to `VHOST_USER_PROTOCOL_F_INBAND_NOTIFICATIONS` and
`VHOST_USER_BACKEND_VRING_CALL`, where it checks the feature with
`vu_has_protocol_feature`?
The name could be `VHOST_USER_PROTOCOL_F_SHARED_OBJECT` (?).
>
>
>> +
>> .. _reply_ack:
>>
>> VHOST_USER_PROTOCOL_F_REPLY_ACK
>> diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
>> index 74a2a28663..5ac5f0eafd 100644
>> --- a/hw/virtio/vhost-user.c
>> +++ b/hw/virtio/vhost-user.c
>> @@ -10,6 +10,7 @@
>>
>> #include "qemu/osdep.h"
>> #include "qapi/error.h"
>> +#include "hw/virtio/virtio-dmabuf.h"
>> #include "hw/virtio/vhost.h"
>> #include "hw/virtio/vhost-user.h"
>> #include "hw/virtio/vhost-backend.h"
>> @@ -20,6 +21,7 @@
>> #include "sysemu/kvm.h"
>> #include "qemu/error-report.h"
>> #include "qemu/main-loop.h"
>> +#include "qemu/uuid.h"
>> #include "qemu/sockets.h"
>> #include "sysemu/runstate.h"
>> #include "sysemu/cryptodev.h"
>> @@ -128,6 +130,7 @@ typedef enum VhostUserSlaveRequest {
>> VHOST_USER_BACKEND_IOTLB_MSG = 1,
>> VHOST_USER_BACKEND_CONFIG_CHANGE_MSG = 2,
>> VHOST_USER_BACKEND_VRING_HOST_NOTIFIER_MSG = 3,
>> + VHOST_USER_BACKEND_SHARED_OBJECT = 6,
>> VHOST_USER_BACKEND_MAX
>> } VhostUserSlaveRequest;
>>
>> @@ -190,6 +193,18 @@ typedef struct VhostUserInflight {
>> uint16_t queue_size;
>> } VhostUserInflight;
>>
>> +typedef enum VhostUserSharedType {
>> + VHOST_SHARED_OBJECT_ADD = 0,
>> + VHOST_SHARED_OBJECT_LOOKUP,
>> + VHOST_SHARED_OBJECT_REMOVE,
>> +} VhostUserSharedType;
>> +
>> +typedef struct VhostUserShared {
>> + unsigned char uuid[16];
>> + VhostUserSharedType type;
>> + int dmabuf_fd;
>> +} VhostUserShared;
>> +
>> typedef struct {
>> VhostUserRequest request;
>>
>> @@ -214,6 +229,7 @@ typedef union {
>> VhostUserCryptoSession session;
>> VhostUserVringArea area;
>> VhostUserInflight inflight;
>> + VhostUserShared object;
>> } VhostUserPayload;
>>
>> typedef struct VhostUserMsg {
>> @@ -1582,6 +1598,52 @@ static int
>> vhost_user_slave_handle_vring_host_notifier(struct vhost_dev *dev,
>> return 0;
>> }
>>
>> +static int vhost_user_backend_handle_shared_object(VhostUserShared
>> *object)
>> +{
>> + QemuUUID uuid;
>> + memcpy(uuid.data, object->uuid, sizeof(object->uuid));
>> +
>> + switch (object->type) {
>> + case VHOST_SHARED_OBJECT_ADD:
>> + return virtio_add_dmabuf(&uuid, object->dmabuf_fd);
>> + case VHOST_SHARED_OBJECT_LOOKUP:
>> + object->dmabuf_fd = virtio_lookup_dmabuf(&uuid);
>> + if (object->dmabuf_fd < 0) {
>> + return object->dmabuf_fd;
>> + }
>> + break;
>> + case VHOST_SHARED_OBJECT_REMOVE:
>> + return virtio_remove_resource(&uuid);
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static bool
>> +vhost_user_backend_send_dmabuf_fd(QIOChannel *ioc, VhostUserHeader *hdr,
>> + VhostUserPayload *payload)
>> +{
>> + Error *local_err = NULL;
>> + struct iovec iov[2];
>> + if (hdr->flags & VHOST_USER_NEED_REPLY_MASK) {
>> + hdr->flags &= ~VHOST_USER_NEED_REPLY_MASK;
>> + hdr->flags |= VHOST_USER_REPLY_MASK;
>> +
>> + hdr->size = sizeof(payload->object);
>> +
>> + iov[0].iov_base = hdr;
>> + iov[0].iov_len = VHOST_USER_HDR_SIZE;
>> + iov[1].iov_base = payload;
>> + iov[1].iov_len = hdr->size;
>> +
>> + if (qio_channel_writev_all(ioc, iov, ARRAY_SIZE(iov),
>> &local_err)) {
>> + error_report_err(local_err);
>> + return false;
>> + }
>> + }
>> + return true;
>> +}
>> +
>> static void close_slave_channel(struct vhost_user *u)
>> {
>> g_source_destroy(u->slave_src);
>> @@ -1639,6 +1701,12 @@ static gboolean slave_read(QIOChannel *ioc,
>> GIOCondition condition,
>> ret = vhost_user_slave_handle_vring_host_notifier(dev,
>> &payload.area,
>> fd ? fd[0] :
>> -1);
>> break;
>> + case VHOST_USER_BACKEND_SHARED_OBJECT:
>> + ret = vhost_user_backend_handle_shared_object(&payload.object);
>> + if (!vhost_user_backend_send_dmabuf_fd(ioc, &hdr, &payload)) {
>> + goto err;
>> + }
>> + break;
>> default:
>> error_report("Received unexpected msg type: %d.", hdr.request);
>> ret = -EINVAL;
>> diff --git a/subprojects/libvhost-user/libvhost-user.c
>> b/subprojects/libvhost-user/libvhost-user.c
>> index 8fb61e2df2..27f16d292a 100644
>> --- a/subprojects/libvhost-user/libvhost-user.c
>> +++ b/subprojects/libvhost-user/libvhost-user.c
>> @@ -1403,6 +1403,94 @@ bool vu_set_queue_host_notifier(VuDev *dev,
>> VuVirtq *vq, int fd,
>> return vu_process_message_reply(dev, &vmsg);
>> }
>>
>> +bool
>> +vu_get_shared_object(VuDev *dev, unsigned char uuid[UUID_LEN], int
>> *dmabuf_fd)
>> +{
>> + bool result = false;
>> + VhostUserMsg msg_reply;
>> + VhostUserMsg msg = {
>> + .request = VHOST_USER_BACKEND_SHARED_OBJECT,
>> + .size = sizeof(msg.payload.object),
>> + .flags = VHOST_USER_VERSION | VHOST_USER_NEED_REPLY_MASK,
>> + .payload.object = {
>> + .type = VHOST_SHARED_OBJECT_LOOKUP,
>> + },
>> + };
>> +
>> + memcpy(msg.payload.object.uuid, uuid, sizeof(uuid[0]) * UUID_LEN);
>> +
>> + pthread_mutex_lock(&dev->slave_mutex);
>> + if (!vu_message_write(dev, dev->slave_fd, &msg)) {
>> + goto out;
>> + }
>> +
>> + if (!vu_message_read_default(dev, dev->slave_fd, &msg_reply)) {
>> + goto out;
>> + }
>> +
>> + if (msg_reply.request != msg.request) {
>> + DPRINT("Received unexpected msg type. Expected %d, received %d",
>> + msg.request, msg_reply.request);
>> + goto out;
>> + }
>> +
>> + *dmabuf_fd = msg_reply.payload.object.dmabuf_fd;
>> + result = *dmabuf_fd > 0;
>> +out:
>> + pthread_mutex_unlock(&dev->slave_mutex);
>> +
>> + return result;
>> +}
>> +
>> +static bool
>> +vu_send_message(VuDev *dev, VhostUserMsg *vmsg)
>> +{
>> + bool result = false;
>> + pthread_mutex_lock(&dev->slave_mutex);
>> + if (!vu_message_write(dev, dev->slave_fd, vmsg)) {
>> + goto out;
>> + }
>> +
>> + result = true;
>> +out:
>> + pthread_mutex_unlock(&dev->slave_mutex);
>> +
>> + return result;
>> +}
>> +
>> +bool
>> +vu_add_shared_object(VuDev *dev, unsigned char uuid[UUID_LEN], int
>> dmabuf_fd)
>> +{
>> + VhostUserMsg msg = {
>> + .request = VHOST_USER_BACKEND_SHARED_OBJECT,
>> + .size = sizeof(msg.payload.object),
>> + .flags = VHOST_USER_VERSION,
>> + .payload.object = {
>> + .dmabuf_fd = dmabuf_fd,
>> + .type = VHOST_SHARED_OBJECT_ADD,
>> + },
>> + };
>> + memcpy(msg.payload.object.uuid, uuid, sizeof(uuid[0]) * UUID_LEN);
>> +
>> + return vu_send_message(dev, &msg);
>> +}
>> +
>> +bool
>> +vu_rm_shared_object(VuDev *dev, unsigned char uuid[UUID_LEN])
>> +{
>> + VhostUserMsg msg = {
>> + .request = VHOST_USER_BACKEND_SHARED_OBJECT,
>> + .size = sizeof(msg.payload.object),
>> + .flags = VHOST_USER_VERSION,
>> + .payload.object = {
>> + .type = VHOST_SHARED_OBJECT_REMOVE,
>> + },
>> + };
>> + memcpy(msg.payload.object.uuid, uuid, sizeof(uuid[0]) * UUID_LEN);
>> +
>> + return vu_send_message(dev, &msg);
>> +}
>> +
>> static bool
>> vu_set_vring_call_exec(VuDev *dev, VhostUserMsg *vmsg)
>> {
>> diff --git a/subprojects/libvhost-user/libvhost-user.h
>> b/subprojects/libvhost-user/libvhost-user.h
>> index 49208cceaa..a43d115bd7 100644
>> --- a/subprojects/libvhost-user/libvhost-user.h
>> +++ b/subprojects/libvhost-user/libvhost-user.h
>> @@ -119,6 +119,7 @@ typedef enum VhostUserSlaveRequest {
>> VHOST_USER_BACKEND_VRING_HOST_NOTIFIER_MSG = 3,
>> VHOST_USER_BACKEND_VRING_CALL = 4,
>> VHOST_USER_BACKEND_VRING_ERR = 5,
>> + VHOST_USER_BACKEND_SHARED_OBJECT = 6,
>> VHOST_USER_BACKEND_MAX
>> } VhostUserSlaveRequest;
>>
>> @@ -172,6 +173,20 @@ typedef struct VhostUserInflight {
>> uint16_t queue_size;
>> } VhostUserInflight;
>>
>> +typedef enum VhostUserSharedType {
>> + VHOST_SHARED_OBJECT_ADD = 0,
>> + VHOST_SHARED_OBJECT_LOOKUP,
>> + VHOST_SHARED_OBJECT_REMOVE,
>> +} VhostUserSharedType;
>> +
>> +#define UUID_LEN 16
>> +
>> +typedef struct VhostUserShared {
>> + unsigned char uuid[UUID_LEN];
>> + VhostUserSharedType type;
>> + int dmabuf_fd;
>> +} VhostUserShared;
>> +
>> #if defined(_WIN32) && (defined(__x86_64__) || defined(__i386__))
>> # define VU_PACKED __attribute__((gcc_struct, packed))
>> #else
>> @@ -199,6 +214,7 @@ typedef struct VhostUserMsg {
>> VhostUserConfig config;
>> VhostUserVringArea area;
>> VhostUserInflight inflight;
>> + VhostUserShared object;
>> } payload;
>>
>> int fds[VHOST_MEMORY_BASELINE_NREGIONS];
>> @@ -539,6 +555,46 @@ void vu_set_queue_handler(VuDev *dev, VuVirtq *vq,
>> bool vu_set_queue_host_notifier(VuDev *dev, VuVirtq *vq, int fd,
>> int size, int offset);
>>
>> +/**
>> + * vu_get_shared_object:
>> + * @dev: a VuDev context
>> + * @uuid: UUID of the shared object
>> + * @dmabuf_fd: output dma-buf file descriptor
>> + *
>> + * Lookup for a virtio shared object (i.e., dma-buf fd) associated with
>> the
>> + * received UUID. Result, if found, is stored in the dmabuf_fd argument.
>> + *
>> + * Returns: whether the virtio object was found.
>> + */
>> +bool vu_get_shared_object(VuDev *dev, unsigned char uuid[UUID_LEN],
>> + int *dmabuf_fd);
>> +
>> +/**
>> + * vu_add_shared_object:
>> + * @dev: a VuDev context
>> + * @uuid: UUID of the shared object
>> + * @dmabuf_fd: output dma-buf file descriptor
>> + *
>> + * Stores a new shared object (i.e., dma-buf fd) in the hash table, and
>> + * associates it with the received UUID.
>> + *
>> + * Returns: TRUE on success, FALSE on failure.
>> + */
>> +bool vu_add_shared_object(VuDev *dev, unsigned char uuid[UUID_LEN],
>> + int dmabuf_fd);
>> +
>> +/**
>> + * vu_rm_shared_object:
>> + * @dev: a VuDev context
>> + * @uuid: UUID of the shared object
>> + *
>> + * Removes a shared object (i.e., dma-buf fd) associated with the
>> + * received UUID from the hash table.
>> + *
>> + * Returns: TRUE on success, FALSE on failure.
>> + */
>> +bool vu_rm_shared_object(VuDev *dev, unsigned char uuid[UUID_LEN]);
>> +
>> /**
>> * vu_queue_set_notification:
>> * @dev: a VuDev context
>> --
>> 2.40.0
>>
>>
>
> --
> Marc-André Lureau
>
Thanks!
Albert Esteve
