From d6e47717b028f0404073d9c60f2fa50d79252333 Mon Sep 17 00:00:00 2001 From: "Dr. David Alan Gilbert" Date: Mon, 12 Mar 2018 17:21:02 +0000 Subject: libvhost-user: Support sending fds back to qemu MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Allow replies with fds (for postcopy) Signed-off-by: Dr. David Alan Gilbert Reviewed-by: Marc-André Lureau Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- contrib/libvhost-user/libvhost-user.c | 30 +++++++++++++++++++++++++++++- 1 file changed, 29 insertions(+), 1 deletion(-) diff --git a/contrib/libvhost-user/libvhost-user.c b/contrib/libvhost-user/libvhost-user.c index 37d4228193..ed9f3148d3 100644 --- a/contrib/libvhost-user/libvhost-user.c +++ b/contrib/libvhost-user/libvhost-user.c @@ -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; } -- cgit v1.2.1