@@ -139,6 +139,7 @@ in the ancillary data:
* VHOST_USER_SET_VRING_KICK
* VHOST_USER_SET_VRING_CALL
* VHOST_USER_SET_VRING_ERR
+ * VHOST_USER_SET_SLAVE_REQ_FD
If Master is unable to send the full message or receives a wrong reply it will
close the connection. An optional reconnection mechanism can be implemented.
@@ -252,6 +253,18 @@ Once the source has finished migration, rings will be stopped by
the source. No further update must be done before rings are
restarted.
+Slave communication
+-------------------
+
+An optional communication channel is provided if the slave declares
+VHOST_USER_PROTOCOL_F_SLAVE_REQ protocol feature, to allow the slave to make
+requests to the master.
+
+The fd is provided via VHOST_USER_SET_SLAVE_REQ_FD ancillary data.
+
+A slave may then send VHOST_USER_SLAVE_* messages to the master
+using this fd communication channel.
+
Protocol features
-----------------
@@ -260,9 +273,10 @@ Protocol features
#define VHOST_USER_PROTOCOL_F_RARP 2
#define VHOST_USER_PROTOCOL_F_REPLY_ACK 3
#define VHOST_USER_PROTOCOL_F_MTU 4
+#define VHOST_USER_PROTOCOL_F_SLAVE_REQ 5
-Message types
--------------
+Master message types
+--------------------
* VHOST_USER_GET_FEATURES
@@ -486,6 +500,18 @@ Message types
If VHOST_USER_PROTOCOL_F_REPLY_ACK is negotiated, slave must respond
with zero in case the specified MTU is valid, or non-zero otherwise.
+ * VHOST_USER_SET_SLAVE_REQ_FD
+
+ Id: 21
+ Equivalent ioctl: N/A
+ Master payload: N/A
+
+ Set the socket file descriptor for slave initiated requests. It is passed
+ in the ancillary data.
+ This request should be sent only when VHOST_USER_F_PROTOCOL_FEATURES
+ has been negotiated, and protocol feature bit VHOST_USER_PROTOCOL_F_SLAVE_REQ
+ bit is present in VHOST_USER_GET_PROTOCOL_FEATURES.
+
VHOST_USER_PROTOCOL_F_REPLY_ACK:
-------------------------------
The original vhost-user specification only demands replies for certain
@@ -33,6 +33,7 @@ enum VhostUserProtocolFeature {
VHOST_USER_PROTOCOL_F_RARP = 2,
VHOST_USER_PROTOCOL_F_REPLY_ACK = 3,
VHOST_USER_PROTOCOL_F_NET_MTU = 4,
+ VHOST_USER_PROTOCOL_F_SLAVE_REQ = 5,
VHOST_USER_PROTOCOL_F_MAX
};
@@ -61,9 +62,15 @@ typedef enum VhostUserRequest {
VHOST_USER_SET_VRING_ENABLE = 18,
VHOST_USER_SEND_RARP = 19,
VHOST_USER_NET_SET_MTU = 20,
+ VHOST_USER_SET_SLAVE_REQ_FD = 21,
VHOST_USER_MAX
} VhostUserRequest;
+typedef enum VhostUserSlaveRequest {
+ VHOST_USER_SLAVE_NONE = 0,
+ VHOST_USER_SLAVE_MAX
+} VhostUserSlaveRequest;
+
typedef struct VhostUserMemoryRegion {
uint64_t guest_phys_addr;
uint64_t memory_size;
@@ -113,6 +120,7 @@ static VhostUserMsg m __attribute__ ((unused));
struct vhost_user {
CharBackend *chr;
+ int slave_fd;
};
static bool ioeventfd_enabled(void)
@@ -574,6 +582,104 @@ static int vhost_user_reset_device(struct vhost_dev *dev)
return 0;
}
+static void slave_read(void *opaque)
+{
+ struct vhost_dev *dev = opaque;
+ struct vhost_user *u = dev->opaque;
+ VhostUserMsg msg = { 0, };
+ int size, ret = 0;
+
+ /* Read header */
+ size = read(u->slave_fd, &msg, VHOST_USER_HDR_SIZE);
+ if (size != VHOST_USER_HDR_SIZE) {
+ error_report("Failed to read from slave.");
+ goto err;
+ }
+
+ if (msg.size > VHOST_USER_PAYLOAD_SIZE) {
+ error_report("Failed to read msg header."
+ " Size %d exceeds the maximum %zu.", msg.size,
+ VHOST_USER_PAYLOAD_SIZE);
+ goto err;
+ }
+
+ /* Read payload */
+ size = read(u->slave_fd, &msg.payload, msg.size);
+ if (size != msg.size) {
+ error_report("Failed to read payload from slave.");
+ goto err;
+ }
+
+ switch (msg.request) {
+ default:
+ error_report("Received unexpected msg type.");
+ ret = -EINVAL;
+ }
+
+ /*
+ * REPLY_ACK feature handling. Other reply types has to be managed
+ * directly in their request handlers.
+ */
+ if (msg.flags & VHOST_USER_NEED_REPLY_MASK) {
+ msg.flags &= ~VHOST_USER_NEED_REPLY_MASK;
+ msg.flags |= VHOST_USER_REPLY_MASK;
+
+ msg.payload.u64 = !!ret;
+ msg.size = sizeof(msg.payload.u64);
+
+ size = write(u->slave_fd, &msg, VHOST_USER_HDR_SIZE + msg.size);
+ if (size != VHOST_USER_HDR_SIZE + msg.size) {
+ error_report("Failed to send msg reply to slave.");
+ goto err;
+ }
+ }
+
+ return;
+
+err:
+ qemu_set_fd_handler(u->slave_fd, NULL, NULL, NULL);
+ close(u->slave_fd);
+ u->slave_fd = -1;
+ return;
+}
+
+static int vhost_setup_slave_channel(struct vhost_dev *dev)
+{
+ VhostUserMsg msg = {
+ .request = VHOST_USER_SET_SLAVE_REQ_FD,
+ .flags = VHOST_USER_VERSION,
+ };
+ struct vhost_user *u = dev->opaque;
+ int sv[2];
+ bool reply_supported = virtio_has_feature(dev->protocol_features,
+ VHOST_USER_PROTOCOL_F_REPLY_ACK);
+
+ if (!virtio_has_feature(dev->protocol_features,
+ VHOST_USER_PROTOCOL_F_SLAVE_REQ)) {
+ return 0;
+ }
+
+ if (socketpair(PF_UNIX, SOCK_STREAM, 0, sv) == -1) {
+ error_report("socketpair() failed");
+ return -1;
+ }
+
+ u->slave_fd = sv[0];
+ qemu_set_fd_handler(u->slave_fd, slave_read, NULL, dev);
+
+ if (reply_supported) {
+ msg.flags |= VHOST_USER_NEED_REPLY_MASK;
+ }
+
+ vhost_user_write(dev, &msg, &sv[1], 1);
+
+ if (reply_supported) {
+ return process_message_reply(dev, msg.request);
+ }
+
+ return 0;
+}
+
static int vhost_user_init(struct vhost_dev *dev, void *opaque)
{
uint64_t features;
@@ -584,6 +690,7 @@ static int vhost_user_init(struct vhost_dev *dev, void *opaque)
u = g_new0(struct vhost_user, 1);
u->chr = opaque;
+ u->slave_fd = -1;
dev->opaque = u;
err = vhost_user_get_features(dev, &features);
@@ -624,6 +731,12 @@ static int vhost_user_init(struct vhost_dev *dev, void *opaque)
"VHOST_USER_PROTOCOL_F_LOG_SHMFD feature.");
}
+
+ err = vhost_setup_slave_channel(dev);
+ if (err < 0) {
+ return err;
+ }
+
return 0;
}
@@ -634,6 +747,10 @@ static int vhost_user_cleanup(struct vhost_dev *dev)
assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER);
u = dev->opaque;
+ if (u->slave_fd >= 0) {
+ close(u->slave_fd);
+ u->slave_fd = -1;
+ }
g_free(u);
dev->opaque = 0;