Update RequestSpec.pci_request for resize

Nova uses the RequestSpec.pci_request in the PciPassthroughFilter to
decide if the PCI devicesm, requested via the pci_alias in the flavor
extra_spec, are available on a potential target host. During resize the
new flavor might contain different pci_alias request than the old flavor
of the instance. In this case Nova should use the pci_alias from the new
flavor to scheduler the destination host of the resize. However this
logic was missing and Nova used the old pci_request value based on the
old flavor. This patch adds the missing logic.

Closes-Bug: #1983753
Closes-Bug: #1941005
Change-Id: I73c9ae27e9c42ee211a53bed3d849650b65f08be

1 files changed, 13 insertions, 0 deletions

diff --git a/nova/compute/api.py b/nova/compute/api.py
index 26ae3cf0f3..66543f57dc 100644
--- a/nova/compute/api.py
+++ b/nova/compute/api.py
@@ -4227,6 +4227,19 @@ class API:
         if not same_flavor:
             request_spec.numa_topology = hardware.numa_get_constraints(
                 new_flavor, instance.image_meta)
+            # if the flavor is changed then we need to recalculate the
+            # pci_requests as well because the new flavor might request
+            # different pci_aliases
+            new_pci_requests = pci_request.get_pci_requests_from_flavor(
+                new_flavor)
+            new_pci_requests.instance_uuid = instance.uuid
+            # The neutron based InstancePCIRequest cannot change during resize,
+            # so we just need to copy them from the old request
+            for request in request_spec.pci_requests.requests or []:
+                if request.source == objects.InstancePCIRequest.NEUTRON_PORT:
+                    new_pci_requests.requests.append(request)
+            request_spec.pci_requests = new_pci_requests
+
             # TODO(huaqiang): Remove in Wallaby
             # check nova-compute nodes have been updated to Victoria to resize
             # instance to a new mixed instance from a dedicated or shared