From 25148854b97ee884ea9194af74e483f7b53c13ef Mon Sep 17 00:00:00 2001
From: Piotr Bartman-Szwarc <prbartman@invisiblethingslab.com>
Date: Tue, 20 Aug 2024 07:39:02 +0200
Subject: [PATCH] q-dev: assignment.device

---
 qubes/device_protocol.py  | 17 +++++++++++++++++
 qubes/devices.py          |  6 +++---
 qubes/ext/utils.py        |  2 +-
 templates/libvirt/xen.xml | 18 ++++++++++--------
 4 files changed, 31 insertions(+), 12 deletions(-)

diff --git a/qubes/device_protocol.py b/qubes/device_protocol.py
index f40d4500f..caaa4ef4a 100644
--- a/qubes/device_protocol.py
+++ b/qubes/device_protocol.py
@@ -1127,6 +1127,23 @@ def devices(self) -> List[DeviceInfo]:
                 result.append(dev)
         return result
 
+    @property
+    def device(self) -> DeviceInfo:
+        """
+        Get single DeviceInfo object or raise an error.
+
+        If port id is set we have exactly one device
+        since we can attach ony one device to one port.
+        If assignment is more general we can get 0 or many devices.
+        """
+        devices = self.devices
+        if len(devices) == 1:
+            return devices[0]
+        if len(devices) > 1:
+            raise ProtocolError("Too many devices matches to assignment")
+        if len(devices) == 0:
+            raise ProtocolError("Any devices matches to assignment")
+
     @property
     def port(self) -> Port:
         """
diff --git a/qubes/devices.py b/qubes/devices.py
index 23cbcb4f7..3f7c26b15 100644
--- a/qubes/devices.py
+++ b/qubes/devices.py
@@ -209,8 +209,8 @@ async def attach(self, assignment: DeviceAssignment):
             raise ValueError(
                 f'Cannot attach ambiguous {assignment.devclass} device.')
 
-        device = assignment.devices[0]
-        if device in [ass.devices[0] for ass in self.get_attached_devices()]:
+        device = assignment.device
+        if device in [ass.device for ass in self.get_attached_devices()]:
             raise DeviceAlreadyAttached(
                 'device {!s} of class {} already attached to {!s}'.format(
                     device, self._bus, self._vm))
@@ -307,7 +307,7 @@ async def detach(self, port: Port):
                 "You need to unassign device first.")
 
         # use the local object, only one device can match
-        port = assignment.devices[0].port
+        port = assignment.device.port
         await self._vm.fire_event_async(
             'device-pre-detach:' + self._bus, pre_event=True, port=port)
 
diff --git a/qubes/ext/utils.py b/qubes/ext/utils.py
index 2841edca1..4a7ae9bf1 100644
--- a/qubes/ext/utils.py
+++ b/qubes/ext/utils.py
@@ -79,7 +79,7 @@ def device_list_change(
     for port_id, frontends in to_attach.items():
         if len(frontends) > 1:
             # unique
-            device = tuple(frontends.values())[0].devices[0]
+            device = tuple(frontends.values())[0].device
             target_name = confirm_device_attachment(device, frontends)
             for front in frontends:
                 if front.name == target_name:
diff --git a/templates/libvirt/xen.xml b/templates/libvirt/xen.xml
index c4d2f819d..80acf3397 100644
--- a/templates/libvirt/xen.xml
+++ b/templates/libvirt/xen.xml
@@ -157,9 +157,10 @@
             {# start external devices from xvdi #}
             {% set counter = {'i': 4} %}
             {% for assignment in vm.devices.block.get_assigned_devices(True) %}
-                {% set device = assignment.devices[0] %}
-                {% set options = assignment.options %}
-                {% include 'libvirt/devices/block.xml' %}
+                {% for device in assignment.devices %}
+                    {% set options = assignment.options %}
+                    {% include 'libvirt/devices/block.xml' %}
+                {% endfor %}
             {% endfor %}
 
             {% if vm.netvm %}
@@ -167,11 +168,12 @@
             {% endif %}
 
             {% for assignment in vm.devices.pci.get_assigned_devices(True) %}
-                {% set device = assignment.devices[0] %}
-                {% set options = assignment.options %}
-                {% set power_mgmt =
-                    vm.app.domains[0].features.get('suspend-s0ix', False) %}
-                {% include 'libvirt/devices/pci.xml' %}
+                {% for device in assignment.devices %}
+                    {% set options = assignment.options %}
+                    {% set power_mgmt =
+                        vm.app.domains[0].features.get('suspend-s0ix', False) %}
+                    {% include 'libvirt/devices/pci.xml' %}
+                {% endfor %}
             {% endfor %}
 
             {% if vm.virt_mode == 'hvm' %}