Debian: use QEMU 5 from buster-backports

This will allow us to make sure of all updates.

'qemu-kvm' got dropped in Debian

Three changes from master are merged into one:
Change Id: If09a8188030baa284dd353b1c3f830d78c5091b7
Change Id: I4371daf7b28c8a057364d17e2e47f6e22665447c
Change Id: I2c82c6269b2c357b0815ea29bc6a7c322f84dac9

Change-Id: I1b3e879ec8752c63dc3f1ec3d8f62c3b43df55f3

docker/base/apt_preferences.debian

@@ -42,8 +42,12 @@ Package: openvswitch*
 Pin: release n=buster
 Pin-Priority: 700
 
-# daxio in nova-compute depends on those
-# in Victoria+ we have them as QEMU 5 dependencies
-Package: libpmem1 libndctl6 libdaxctl1 pmdk-tools libpmemblk1 libpmemlog1 libpmemobj1 libpmempool1
+# we want newer QEMU
+Package: qemu*
+Pin: version 1:5.*
+Pin-Priority: 700
+
+# daxio and QEMU depends on those
+Package: libpmem1 libndctl6 libdaxctl1 pmdk-tools libpmemblk1 libpmemlog1 libpmemobj1 libpmempool1 liburing1 libfdt1
 Pin: release n=buster-backports
 Pin-Priority: 700

docker/nova/nova-libvirt/Dockerfile.j2

@@ -59,8 +59,13 @@ LABEL maintainer="{{ maintainer }}" name="{{ image_name }}" build-date="{{ build
     {% elif base_arch == "x86_64" %}
         {% set nova_libvirt_packages = nova_libvirt_packages + [
             'ovmf',
-            'qemu-kvm'
         ] %}
+        # NOTE(hrw): Debian merged 'qemu-kvm' into 'qemu-system-ARCH' in 5.0-9
+        {% if base_distro == 'ubuntu' %}
+            {% set nova_libvirt_packages = nova_libvirt_packages + [
+                'qemu-kvm'
+            ] %}
+        {% endif %}
     {% endif %}
 
     {% if base_arch in ['aarch64', 'x86_64'] %}