From 13384f158ce043744cf7542162a34953c7e05a70 Mon Sep 17 00:00:00 2001
From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Date: Mon, 2 Oct 2017 20:15:21 +0100
Subject: [PATCH] libvhost-user: Support VHOST_USER_SET_SLAVE_REQ_FD
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Allow the qemu to pass us a slave fd.  We don't do anything
with it yet.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20171002191521.15748-5-dgilbert@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
---
 contrib/libvhost-user/libvhost-user.c | 27 ++++++++++++++++++++++++++-
 contrib/libvhost-user/libvhost-user.h |  1 +
 2 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/contrib/libvhost-user/libvhost-user.c b/contrib/libvhost-user/libvhost-user.c
index e36aed72d0..f409bd3d41 100644
--- a/contrib/libvhost-user/libvhost-user.c
+++ b/contrib/libvhost-user/libvhost-user.c
@@ -726,7 +726,8 @@ vu_set_vring_err_exec(VuDev *dev, VhostUserMsg *vmsg)
 static bool
 vu_get_protocol_features_exec(VuDev *dev, VhostUserMsg *vmsg)
 {
-    uint64_t features = 1ULL << VHOST_USER_PROTOCOL_F_LOG_SHMFD;
+    uint64_t features = 1ULL << VHOST_USER_PROTOCOL_F_LOG_SHMFD |
+                        1ULL << VHOST_USER_PROTOCOL_F_SLAVE_REQ;
 
     if (dev->iface->get_protocol_features) {
         features |= dev->iface->get_protocol_features(dev);
@@ -779,6 +780,23 @@ vu_set_vring_enable_exec(VuDev *dev, VhostUserMsg *vmsg)
     return false;
 }
 
+static bool
+vu_set_slave_req_fd(VuDev *dev, VhostUserMsg *vmsg)
+{
+    if (vmsg->fd_num != 1) {
+        vu_panic(dev, "Invalid slave_req_fd message (%d fd's)", vmsg->fd_num);
+        return false;
+    }
+
+    if (dev->slave_fd != -1) {
+        close(dev->slave_fd);
+    }
+    dev->slave_fd = vmsg->fds[0];
+    DPRINT("Got slave_fd: %d\n", vmsg->fds[0]);
+
+    return false;
+}
+
 static bool
 vu_process_message(VuDev *dev, VhostUserMsg *vmsg)
 {
@@ -842,6 +860,8 @@ vu_process_message(VuDev *dev, VhostUserMsg *vmsg)
         return vu_get_queue_num_exec(dev, vmsg);
     case VHOST_USER_SET_VRING_ENABLE:
         return vu_set_vring_enable_exec(dev, vmsg);
+    case VHOST_USER_SET_SLAVE_REQ_FD:
+        return vu_set_slave_req_fd(dev, vmsg);
     case VHOST_USER_NONE:
         break;
     default:
@@ -915,6 +935,10 @@ vu_deinit(VuDev *dev)
 
 
     vu_close_log(dev);
+    if (dev->slave_fd != -1) {
+        close(dev->slave_fd);
+        dev->slave_fd = -1;
+    }
 
     if (dev->sock != -1) {
         close(dev->sock);
@@ -945,6 +969,7 @@ vu_init(VuDev *dev,
     dev->remove_watch = remove_watch;
     dev->iface = iface;
     dev->log_call_fd = -1;
+    dev->slave_fd = -1;
     for (i = 0; i < VHOST_MAX_NR_VIRTQUEUE; i++) {
         dev->vq[i] = (VuVirtq) {
             .call_fd = -1, .kick_fd = -1, .err_fd = -1,
diff --git a/contrib/libvhost-user/libvhost-user.h b/contrib/libvhost-user/libvhost-user.h
index d54683feeb..2f5864b5c4 100644
--- a/contrib/libvhost-user/libvhost-user.h
+++ b/contrib/libvhost-user/libvhost-user.h
@@ -226,6 +226,7 @@ struct VuDev {
     VuDevRegion regions[VHOST_MEMORY_MAX_NREGIONS];
     VuVirtq vq[VHOST_MAX_NR_VIRTQUEUE];
     int log_call_fd;
+    int slave_fd;
     uint64_t log_size;
     uint8_t *log_table;
     uint64_t features;