alt Hacker NewsIs Nvidia’s Fabric Manager and other control plane software Open Source? If so, that’s news to me. It’s not clear that anything in this article relates to Open Source at all; publishing how to do VM management doesn’t qualify. Maybe “open kimono.”
Also, how strong are the security boundaries among multiple tenants when configured in this way? I know, for example, that AWS is extremely careful about how hardware resources are shared across tenants of a physical host to prevent cross-tenant data leakage.
Fabric Manager itself is not open source. It's NVIDIA-provided software, and today it's required to bring up and manage the NVLink/NVSwitch fabric on HGX systems. What we meant by "open" is that everything around it - the hypervisor, our control plane logic, partition selection, host configuration, etc. - is implemented in the open and available in our repos. You're right that this isn't a fully open GPU stack.
On isolation: in Shared NVSwitch Multitenancy mode, isolation is enforced at multiple layers. Fabric Manager programs the NVSwitch routing tables so GPUs in different partitions cannot exchange NVLink traffic, and each VM receives exclusive ownership of its assigned GPUs via VFIO passthrough. Large providers apply additional hardening and operational controls beyond what we describe here. We're not claiming this is equivalent to AWS's internal threat model, but it does rely on NVIDIA's documented isolation mechanisms.