Failed to run instance with flavor set with GPU Passthrough, Exceeded max scheduling attempts 3 for instance a3927c7e-cfce-4f2d-bf0f-64ffabd449a6. Last exception: XML error: Hostdev already exists in the domain configuration

Issue

• We have enable pci passthrough for gpu, we use tesla t4 .

• During process creation we facing error like this:

 Exceeded maximum number of retries. Exceeded max scheduling attempts 3 for instance a3927c7e-cfce-4f2d-bf0f-64ffabd449a6. Last exception: XML error: Hostdev already exists in the domain configuration 

• This is the flavor being used:

[stack@director ~]$ openstack flavor show  a05ab4e0-83e4-4417-aa53-f60480eaa691
+----------------------------+--------------------------------------+
| Field                      | Value                                |
+----------------------------+--------------------------------------+
| OS-FLV-DISABLED:disabled   | False                                |
| OS-FLV-EXT-DATA:ephemeral  | 0                                    |
| access_project_ids         | None                                 |
| description                | None                                 |
| disk                       | 200                                  |
| id                         | a05ab4e0-83e4-4417-aa53-f60480eaa691 |
| name                       | C16M64D200-GPU                       |
| os-flavor-access:is_public | True                                 |
| properties                 | pci_passthrough:alias='t4:1'         |
| ram                        | 65536                                |
| rxtx_factor                | 1.0                                  |
| swap                       |                                      |
| vcpus                      | 16                                   |
+----------------------------+--------------------------------------+

• Here's the nova.conf for pci passthrough/alias:

$ cat nova.conf  | grep alias
alias={"device_type":"type-PF","name":"t4","product_id":"1eb8","vendor_id":"10de"}
$ cat nova.conf  | grep whitelist
passthrough_whitelist={"product_id":"1eb8","vendor_id":"10de"}

• lspci from the compute:

$ grep -i nvidia lspci 
5e:00.0 3D controller [0302]: NVIDIA Corporation TU104GL [Tesla T4] [10de:1eb8] (rev a1)