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vhost-user: add slave-req-fd support

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Learn to give a socket to the slave to let him make requests to the
master.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Marc-André Lureau 2017-06-02 12:18:30 +02:00 committed by Michael S. Tsirkin
parent 2152f3fead
commit 4bbeeba023
2 changed files with 157 additions and 2 deletions
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32
docs/specs/vhost-user.txt
View File

@ -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 +500,20 @@ 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.
If VHOST_USER_PROTOCOL_F_REPLY_ACK is negotiated, slave must respond
with zero for success, non-zero otherwise.
VHOST_USER_PROTOCOL_F_REPLY_ACK:
-------------------------------
The original vhost-user specification only demands replies for certain

127
hw/virtio/vhost-user.c
View File

@ -32,6 +32,7 @@ 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
};
@ -60,9 +61,15 @@ 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;
@ -112,6 +119,7 @@ static VhostUserMsg m __attribute__ ((unused));
struct vhost_user {
CharBackend *chr;
int slave_fd;
};
static bool ioeventfd_enabled(void)
@ -578,6 +586,115 @@ 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], ret = 0;
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;
}
ret = vhost_user_write(dev, &msg, &sv[1], 1);
if (ret) {
goto out;
}
if (reply_supported) {
ret = process_message_reply(dev, &msg);
}
out:
close(sv[1]);
if (ret) {
qemu_set_fd_handler(u->slave_fd, NULL, NULL, NULL);
close(u->slave_fd);
u->slave_fd = -1;
}
return ret;
}
static int vhost_user_init(struct vhost_dev *dev, void *opaque)
{
uint64_t features;
@ -588,6 +705,7 @@ 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);
@ -628,6 +746,11 @@ 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;
}
@ -638,6 +761,10 @@ 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;