I have two GPU cards, all of them was connect with one same numa CPU socket as below link info: https://paste.opendev.org/show/b7Qi8qCnbLVxO2W0JdQw/ I can boot one nova instance successfully with the two GPU cards by PCI Passthrough way. but in the booted instances, use deviceQuery method would get the below message: Peer access from NVIDIA RTX 6000(GPU0) -> NVIDIA RTX 6000(GPU1): NO Peer access from NVIDIA RTX 6000(GPU1) -> NVIDIA RTX 6000(GPU0): NO The expected return should be as below： Peer access from NVIDIA RTX 6000(GPU0) -> NVIDIA RTX 6000(GPU1): YES Peer access from NVIDIA RTX 6000(GPU1) -> NVIDIA RTX 6000(GPU0): YES so that the memory can be shared between the two GPUs. I'm running Openstack Xena release in Intel Xeon Gold 5220R CPU