Revert "vhost-user: Attempt to fix a race with set_mem_table."

This reverts commit 28ed5ef.

I still think it's the right thing to do, but
tests have been failing sporadically.

Revert for now, and hope to fix it before the release.

Cc: Prerna Saxena <prerna.saxena@nutanix.com>
Cc: Peter Maydell <peter.maydell@linaro.org>
Cc: Marc-André Lureau <mlureau@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Message-id: 1471268075-3425-1-git-send-email-mst@redhat.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

hw/virtio/vhost-user.c

@@ -263,6 +263,66 @@ static int vhost_user_set_log_base(struct vhost_dev *dev, uint64_t base,
     return 0;
 }
 
+static int vhost_user_set_mem_table(struct vhost_dev *dev,
+                                    struct vhost_memory *mem)
+{
+    int fds[VHOST_MEMORY_MAX_NREGIONS];
+    int i, fd;
+    size_t fd_num = 0;
+    bool reply_supported = virtio_has_feature(dev->protocol_features,
+                                              VHOST_USER_PROTOCOL_F_REPLY_ACK);
+
+    VhostUserMsg msg = {
+        .request = VHOST_USER_SET_MEM_TABLE,
+        .flags = VHOST_USER_VERSION,
+    };
+
+    if (reply_supported) {
+        msg.flags |= VHOST_USER_NEED_REPLY_MASK;
+    }
+
+    for (i = 0; i < dev->mem->nregions; ++i) {
+        struct vhost_memory_region *reg = dev->mem->regions + i;
+        ram_addr_t offset;
+        MemoryRegion *mr;
+
+        assert((uintptr_t)reg->userspace_addr == reg->userspace_addr);
+        mr = memory_region_from_host((void *)(uintptr_t)reg->userspace_addr,
+                                     &offset);
+        fd = memory_region_get_fd(mr);
+        if (fd > 0) {
+            msg.payload.memory.regions[fd_num].userspace_addr = reg->userspace_addr;
+            msg.payload.memory.regions[fd_num].memory_size  = reg->memory_size;
+            msg.payload.memory.regions[fd_num].guest_phys_addr = reg->guest_phys_addr;
+            msg.payload.memory.regions[fd_num].mmap_offset = offset;
+            assert(fd_num < VHOST_MEMORY_MAX_NREGIONS);
+            fds[fd_num++] = fd;
+        }
+    }
+
+    msg.payload.memory.nregions = fd_num;
+
+    if (!fd_num) {
+        error_report("Failed initializing vhost-user memory map, "
+                     "consider using -object memory-backend-file share=on");
+        return -1;
+    }
+
+    msg.size = sizeof(msg.payload.memory.nregions);
+    msg.size += sizeof(msg.payload.memory.padding);
+    msg.size += fd_num * sizeof(VhostUserMemoryRegion);
+
+    if (vhost_user_write(dev, &msg, fds, fd_num) < 0) {
+        return -1;
+    }
+
+    if (reply_supported) {
+        return process_message_reply(dev, msg.request);
+    }
+
+    return 0;
+}
+
 static int vhost_user_set_vring_addr(struct vhost_dev *dev,
                                      struct vhost_vring_addr *addr)
 {
@@ -477,73 +537,6 @@ static int vhost_user_get_features(struct vhost_dev *dev, uint64_t *features)
     return vhost_user_get_u64(dev, VHOST_USER_GET_FEATURES, features);
 }
 
-static int vhost_user_set_mem_table(struct vhost_dev *dev,
-                                    struct vhost_memory *mem)
-{
-    int fds[VHOST_MEMORY_MAX_NREGIONS];
-    int i, fd;
-    size_t fd_num = 0;
-    uint64_t features;
-    bool reply_supported = virtio_has_feature(dev->protocol_features,
-                                              VHOST_USER_PROTOCOL_F_REPLY_ACK);
-
-    VhostUserMsg msg = {
-        .request = VHOST_USER_SET_MEM_TABLE,
-        .flags = VHOST_USER_VERSION,
-    };
-
-    if (reply_supported) {
-        msg.flags |= VHOST_USER_NEED_REPLY_MASK;
-    }
-
-    for (i = 0; i < dev->mem->nregions; ++i) {
-        struct vhost_memory_region *reg = dev->mem->regions + i;
-        ram_addr_t offset;
-        MemoryRegion *mr;
-
-        assert((uintptr_t)reg->userspace_addr == reg->userspace_addr);
-        mr = memory_region_from_host((void *)(uintptr_t)reg->userspace_addr,
-                                     &offset);
-        fd = memory_region_get_fd(mr);
-        if (fd > 0) {
-            msg.payload.memory.regions[fd_num].userspace_addr
-                                             = reg->userspace_addr;
-            msg.payload.memory.regions[fd_num].memory_size  = reg->memory_size;
-            msg.payload.memory.regions[fd_num].guest_phys_addr
-                                             = reg->guest_phys_addr;
-            msg.payload.memory.regions[fd_num].mmap_offset = offset;
-            assert(fd_num < VHOST_MEMORY_MAX_NREGIONS);
-            fds[fd_num++] = fd;
-        }
-    }
-
-    msg.payload.memory.nregions = fd_num;
-
-    if (!fd_num) {
-        error_report("Failed initializing vhost-user memory map, "
-                     "consider using -object memory-backend-file share=on");
-        return -1;
-    }
-
-    msg.size = sizeof(msg.payload.memory.nregions);
-    msg.size += sizeof(msg.payload.memory.padding);
-    msg.size += fd_num * sizeof(VhostUserMemoryRegion);
-
-    vhost_user_write(dev, &msg, fds, fd_num);
-
-    if (reply_supported) {
-        return process_message_reply(dev, msg.request);
-    } else {
-        /* Note: It is (yet) unknown when the client application has finished
-         * remapping the GPA.
-         * Attempt to prevent a race by sending a command that requires a reply.
-         */
-        vhost_user_get_features(dev, &features);
-    }
-
-    return 0;
-}
-
 static int vhost_user_set_owner(struct vhost_dev *dev)
 {
     VhostUserMsg msg = {