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libvhost-user: handle shared_object msg
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In the libvhost-user library we need to
handle VHOST_USER_GET_SHARED_OBJECT requests,
and add helper functions to allow sending messages
to interact with the virtio shared objects
hash table.

Signed-off-by: Albert Esteve <aesteve@redhat.com>
Message-Id: <20231002065706.94707-5-aesteve@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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@aesteve-rh @mstsirkin
aesteve-rh authored and mstsirkin committed Oct 4, 2023
1 parent d714bc6 commit 603cf71
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Showing 2 changed files with 174 additions and 1 deletion.
120 changes: 120 additions & 0 deletions subprojects/libvhost-user/libvhost-user.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -161,6 +161,7 @@ vu_request_to_string(unsigned int req)
REQ(VHOST_USER_GET_MAX_MEM_SLOTS),
REQ(VHOST_USER_ADD_MEM_REG),
REQ(VHOST_USER_REM_MEM_REG),
REQ(VHOST_USER_GET_SHARED_OBJECT),
REQ(VHOST_USER_MAX),
};
#undef REQ
Expand Down Expand Up @@ -901,6 +902,24 @@ vu_rem_mem_reg(VuDev *dev, VhostUserMsg *vmsg) {
return false;
}

static bool
vu_get_shared_object(VuDev *dev, VhostUserMsg *vmsg)
{
int fd_num = 0;
int dmabuf_fd = -1;
if (dev->iface->get_shared_object) {
dmabuf_fd = dev->iface->get_shared_object(
dev, &vmsg->payload.object.uuid[0]);
}
if (dmabuf_fd != -1) {
DPRINT("dmabuf_fd found for requested UUID\n");
vmsg->fds[fd_num++] = dmabuf_fd;
}
vmsg->fd_num = fd_num;

return true;
}

static bool
vu_set_mem_table_exec_postcopy(VuDev *dev, VhostUserMsg *vmsg)
{
Expand Down Expand Up @@ -1404,6 +1423,105 @@ bool vu_set_queue_host_notifier(VuDev *dev, VuVirtq *vq, int fd,
return vu_process_message_reply(dev, &vmsg);
}

bool
vu_lookup_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_LOOKUP,
.size = sizeof(msg.payload.object),
.flags = VHOST_USER_VERSION | VHOST_USER_NEED_REPLY_MASK,
};

memcpy(msg.payload.object.uuid, uuid, sizeof(uuid[0]) * UUID_LEN);

if (!vu_has_protocol_feature(dev, VHOST_USER_PROTOCOL_F_SHARED_OBJECT)) {
return false;
}

pthread_mutex_lock(&dev->backend_mutex);
if (!vu_message_write(dev, dev->backend_fd, &msg)) {
goto out;
}

if (!vu_message_read_default(dev, dev->backend_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;
}

if (msg_reply.fd_num != 1) {
DPRINT("Received unexpected number of fds. Expected 1, received %d",
msg_reply.fd_num);
goto out;
}

*dmabuf_fd = msg_reply.fds[0];
result = *dmabuf_fd > 0 && msg_reply.payload.u64 == 0;
out:
pthread_mutex_unlock(&dev->backend_mutex);

return result;
}

static bool
vu_send_message(VuDev *dev, VhostUserMsg *vmsg)
{
bool result = false;
pthread_mutex_lock(&dev->backend_mutex);
if (!vu_message_write(dev, dev->backend_fd, vmsg)) {
goto out;
}

result = true;
out:
pthread_mutex_unlock(&dev->backend_mutex);

return result;
}

bool
vu_add_shared_object(VuDev *dev, unsigned char uuid[UUID_LEN])
{
VhostUserMsg msg = {
.request = VHOST_USER_BACKEND_SHARED_OBJECT_ADD,
.size = sizeof(msg.payload.object),
.flags = VHOST_USER_VERSION,
};

memcpy(msg.payload.object.uuid, uuid, sizeof(uuid[0]) * UUID_LEN);

if (!vu_has_protocol_feature(dev, VHOST_USER_PROTOCOL_F_SHARED_OBJECT)) {
return false;
}

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_REMOVE,
.size = sizeof(msg.payload.object),
.flags = VHOST_USER_VERSION,
};

memcpy(msg.payload.object.uuid, uuid, sizeof(uuid[0]) * UUID_LEN);

if (!vu_has_protocol_feature(dev, VHOST_USER_PROTOCOL_F_SHARED_OBJECT)) {
return false;
}

return vu_send_message(dev, &msg);
}

static bool
vu_set_vring_call_exec(VuDev *dev, VhostUserMsg *vmsg)
{
Expand Down Expand Up @@ -1944,6 +2062,8 @@ vu_process_message(VuDev *dev, VhostUserMsg *vmsg)
return vu_add_mem_reg(dev, vmsg);
case VHOST_USER_REM_MEM_REG:
return vu_rem_mem_reg(dev, vmsg);
case VHOST_USER_GET_SHARED_OBJECT:
return vu_get_shared_object(dev, vmsg);
default:
vmsg_close_fds(vmsg);
vu_panic(dev, "Unhandled request: %d", vmsg->request);
Expand Down
55 changes: 54 additions & 1 deletion subprojects/libvhost-user/libvhost-user.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -64,7 +64,8 @@ enum VhostUserProtocolFeature {
VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD = 12,
VHOST_USER_PROTOCOL_F_INBAND_NOTIFICATIONS = 14,
VHOST_USER_PROTOCOL_F_CONFIGURE_MEM_SLOTS = 15,

/* Feature 16 is reserved for VHOST_USER_PROTOCOL_F_STATUS. */
VHOST_USER_PROTOCOL_F_SHARED_OBJECT = 17,
VHOST_USER_PROTOCOL_F_MAX
};

Expand Down Expand Up @@ -109,6 +110,7 @@ typedef enum VhostUserRequest {
VHOST_USER_GET_MAX_MEM_SLOTS = 36,
VHOST_USER_ADD_MEM_REG = 37,
VHOST_USER_REM_MEM_REG = 38,
VHOST_USER_GET_SHARED_OBJECT = 41,
VHOST_USER_MAX
} VhostUserRequest;

Expand All @@ -119,6 +121,9 @@ typedef enum VhostUserBackendRequest {
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_ADD = 6,
VHOST_USER_BACKEND_SHARED_OBJECT_REMOVE = 7,
VHOST_USER_BACKEND_SHARED_OBJECT_LOOKUP = 8,
VHOST_USER_BACKEND_MAX
} VhostUserBackendRequest;

Expand Down Expand Up @@ -172,6 +177,12 @@ typedef struct VhostUserInflight {
uint16_t queue_size;
} VhostUserInflight;

#define UUID_LEN 16

typedef struct VhostUserShared {
unsigned char uuid[UUID_LEN];
} VhostUserShared;

#if defined(_WIN32) && (defined(__x86_64__) || defined(__i386__))
# define VU_PACKED __attribute__((gcc_struct, packed))
#else
Expand Down Expand Up @@ -199,6 +210,7 @@ typedef struct VhostUserMsg {
VhostUserConfig config;
VhostUserVringArea area;
VhostUserInflight inflight;
VhostUserShared object;
} payload;

int fds[VHOST_MEMORY_BASELINE_NREGIONS];
Expand Down Expand Up @@ -232,6 +244,7 @@ typedef int (*vu_get_config_cb) (VuDev *dev, uint8_t *config, uint32_t len);
typedef int (*vu_set_config_cb) (VuDev *dev, const uint8_t *data,
uint32_t offset, uint32_t size,
uint32_t flags);
typedef int (*vu_get_shared_object_cb) (VuDev *dev, const unsigned char *uuid);

typedef struct VuDevIface {
/* called by VHOST_USER_GET_FEATURES to get the features bitmask */
Expand All @@ -258,6 +271,8 @@ typedef struct VuDevIface {
vu_get_config_cb get_config;
/* set the config space of the device */
vu_set_config_cb set_config;
/* get virtio shared object from the underlying vhost implementation. */
vu_get_shared_object_cb get_shared_object;
} VuDevIface;

typedef void (*vu_queue_handler_cb) (VuDev *dev, int qidx);
Expand Down Expand Up @@ -541,6 +556,44 @@ 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_lookup_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_lookup_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
*
* Registers this back-end as the exporter for the object associated with
* the received UUID.
*
* Returns: TRUE on success, FALSE on failure.
*/
bool vu_add_shared_object(VuDev *dev, unsigned char uuid[UUID_LEN]);

/**
* vu_rm_shared_object:
* @dev: a VuDev context
* @uuid: UUID of the shared object
*
* Removes a shared object entry (i.e., back-end entry) associated with the
* received UUID key 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
Expand Down

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