Merge "libvirt: Switch the default video model from 'cirrus' to 'virtio'"

nova/virt/libvirt/config.py

@@ -2056,7 +2056,7 @@ class LibvirtConfigGuestVideo(LibvirtConfigGuestDevice):
         super(LibvirtConfigGuestVideo, self).__init__(root_name="video",
                                                       **kwargs)
 
-        self.type = 'cirrus'
+        self.type = 'virtio'
         self.vram = None
         self.heads = None
         self.driver_iommu = False

nova/virt/libvirt/driver.py

@@ -5940,6 +5940,15 @@ class LibvirtDriver(driver.ComputeDriver):
         guestarch = libvirt_utils.get_arch(image_meta)
         if CONF.libvirt.virt_type == 'parallels':
             video.type = 'vga'
+        # NOTE(kchamart): 'virtio' is a sensible default whether or not
+        # the guest has the native kernel driver (called "virtio-gpu" in
+        # Linux) -- i.e. if the guest has the VirtIO GPU driver, it'll
+        # be used; otherwise, the 'virtio' model will gracefully
+        # fallback to VGA compatibiliy mode.
+        elif (guestarch in (fields.Architecture.I686,
+                            fields.Architecture.X86_64) and not
+                            CONF.spice.enabled):
+            video.type = 'virtio'
         elif guestarch in (fields.Architecture.PPC,
                            fields.Architecture.PPC64,
                            fields.Architecture.PPC64LE):

releasenotes/notes/virtio-as-default-display-device-5341d3d5180036e2.yaml

@@ -0,0 +1,9 @@
+---
+features:
+  - |
+    From this release, Nova instances will get ``virtio`` as the default
+    display device (instead of ``cirrus``, which has many limitations).
+    If your guest has a native kernel (called "virtio-gpu" in Linux;
+    available since  Linux 4.4 and above) driver, then it'll be used;
+    otherwise, the 'virtio' model will gracefully fallback to VGA
+    compatibiliy mode, which is still better than ``cirrus``.