I would like to resize an instance with PCI devices (GPU Passthrough) to  a flavor without PCI Devices, but nova-api return no valid host.

Response: No valid host was found. No valid host found for resize (HTTP 400) (Request-ID: req-9d6cf3f9-8f6f-482f-b0b1-95ec286a0fc3)

I checked nova-scheduler log: 

Filtering removed all hosts for the request with instance ID 'e7b607ef-6be5-4bbc-9849-e31d622ecdfe'. Filter results: ['AggregateInstanceExtraSpecsFilter: (start: 85, end: 44)', 'RetryFilter: (start: 44, end: 44)', 'AvailabilityZoneFilter: (start: 44, end: 29)', 'ComputeFilter: (start: 29, end: 29)', 'ImagePropertiesFilter: (start: 29, end: 29)', 'ServerGroupAntiAffinityFilter: (start: 29, end: 29)', 'ServerGroupAffinityFilter: (start: 29, end: 29)', 'PciPassthroughFilter: (start: 29, end: 0)']

Actually, new flavor is not contain PCI specs, But It cannot pass PCI Filter.

Thanks & Regards