Multiple GPU Assignments to a Single Hyper-V VM with DDA
I recently configured Discrete Device Assignment (DDA) on my Windows Server with Hyper-V and successfully assigned a GPU to a virtual machine using the steps outlined in the following reference manuals https://docs.nvidia.com/grid/5.0/grid-vgpu-user-guide/index.html#using-gpu-pass-through-windows-server-hyper-v https://learn.microsoft.com/en-us/windows-server/virtualization/hyper-v/deploy/deploying-graphics-devices-using-dda https://learn.microsoft.com/en-us/windows-server/virtualization/hyper-v/plan/plan-for-deploying-devices-using-discrete-device-assignment My Setup: - Windows Server with Hyper-V - Multiple GPUs available (Example: NVIDIA RTX A400) What I've Done: Successfully assigned one GPU to a VM using DDA - Obtain the location path of the GPU that I want to assign to a VM: "PCIROOT(36)#PCI(0000)#PCI(0000)" - Dismount the device: Dismount-VMHostAssignableDevice -LocationPath "PCIROOT(36)#PCI(0000)#PCI(0000)" -Force - Assign the device to the VM: Add-VMAssignableDevice -LocationPath "PCIROOT(36)#PCI(0000)#PCI(0000)" -VMName Debian12_Dev Power on the VM, and the guest OS (Debian) is able to use the GPU. Now, I want to add multiple GPUs to a single VM using Hyper-V DDA. I tried the following: - Obtain the location path of GPU1 & GPU2 that I want to assign to a VM: - GPU1 device location path: `PCIROOT(80)#PCI(0200)#PCI(0000)#PCI(1000)#PCI(0000)` - GPU2 device location path: `PCIROOT(36)#PCI(0000)#PCI(0000)`- Dismount the devices: - Dismount the devices: Dismount-VMHostAssignableDevice -LocationPath "PCIROOT(80)#PCI(0200)#PCI(0000)#PCI(1000)#PCI(0000)" -Force Dismount-VMHostAssignableDevice -LocationPath "PCIROOT(36)#PCI(0000)#PCI(0000)" -Force - Assign the devices to the VM: Add-VMAssignableDevice -LocationPath "PCIROOT(36)#PCI(0000)#PCI(0000)" -VMName Debian12_Dev Add-VMAssignableDevice -LocationPath "PCIROOT(80)#PCI(0200)#PCI(0000)#PCI(1000)#PCI(0000)" -VMName Debian12_Dev Power on the VM, but the guest OS (Debian) identifies only one GPU. Question: Has anyone tried adding multiple GPUs to a single VM using Hyper-V DDA? If so, what steps did you follow, and did you encounter any challenges? I'm seeking to optimize GPU resources for specific workloads within a single VM and would appreciate any insights, experiences, or tips from the community. Thanks in advance!