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libvhost-user: Support sending fds back to qemu

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Allow replies with fds (for postcopy)

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Dr. David Alan Gilbert 2018-03-12 17:21:02 +00:00 committed by Michael S. Tsirkin
parent d3dff7a5a1
commit d6e47717b0
1 changed files with 29 additions and 1 deletions
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30
contrib/libvhost-user/libvhost-user.c
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@ -246,6 +246,31 @@ vu_message_write(VuDev *dev, int conn_fd, VhostUserMsg *vmsg)
{
int rc;
uint8_t *p = (uint8_t *)vmsg;
char control[CMSG_SPACE(VHOST_MEMORY_MAX_NREGIONS * sizeof(int))] = { };
struct iovec iov = {
.iov_base = (char *)vmsg,
.iov_len = VHOST_USER_HDR_SIZE,
};
struct msghdr msg = {
.msg_iov = &iov,
.msg_iovlen = 1,
.msg_control = control,
};
struct cmsghdr *cmsg;
memset(control, 0, sizeof(control));
assert(vmsg->fd_num <= VHOST_MEMORY_MAX_NREGIONS);
if (vmsg->fd_num > 0) {
size_t fdsize = vmsg->fd_num * sizeof(int);
msg.msg_controllen = CMSG_SPACE(fdsize);
cmsg = CMSG_FIRSTHDR(&msg);
cmsg->cmsg_len = CMSG_LEN(fdsize);
cmsg->cmsg_level = SOL_SOCKET;
cmsg->cmsg_type = SCM_RIGHTS;
memcpy(CMSG_DATA(cmsg), vmsg->fds, fdsize);
} else {
msg.msg_controllen = 0;
}
/* Set the version in the flags when sending the reply */
vmsg->flags &= ~VHOST_USER_VERSION_MASK;
@ -253,7 +278,7 @@ vu_message_write(VuDev *dev, int conn_fd, VhostUserMsg *vmsg)
vmsg->flags |= VHOST_USER_REPLY_MASK;
do {
rc = write(conn_fd, p, VHOST_USER_HDR_SIZE);
rc = sendmsg(conn_fd, &msg, 0);
} while (rc < 0 && (errno == EINTR || errno == EAGAIN));
do {
@ -346,6 +371,7 @@ vu_get_features_exec(VuDev *dev, VhostUserMsg *vmsg)
}
vmsg->size = sizeof(vmsg->payload.u64);
vmsg->fd_num = 0;
DPRINT("Sending back to guest u64: 0x%016"PRIx64"\n", vmsg->payload.u64);
@ -501,6 +527,7 @@ vu_set_log_base_exec(VuDev *dev, VhostUserMsg *vmsg)
dev->log_size = log_mmap_size;
vmsg->size = sizeof(vmsg->payload.u64);
vmsg->fd_num = 0;
return true;
}
@ -759,6 +786,7 @@ vu_get_protocol_features_exec(VuDev *dev, VhostUserMsg *vmsg)
vmsg->payload.u64 = features;
vmsg->size = sizeof(vmsg->payload.u64);
vmsg->fd_num = 0;
return true;
}