Passthrough GPU to both LXC and VM simultaneously

[lucascbd]

Hi,
Is it possible to simultaneously passthrough GPU to LXC and VM?
I currently have a LXC running my Plex Server and the GPU passthrough works flawlessly but I also have a Windows 10 VM that I use sometimes and I'd like to use my GPU in order to achieve full HD resolution when running Windows.

The problem is, in order to passthrough to the LXC I must disable IOMMU, and to achieve the same with the VM I need to enable IOMMU.
Is there a way to make it work simultaneously?

Best regards!

 

[leesteken]

Is it possible to simultaneously passthrough GPU to LXC and VM?

A PCIe devices can only be part of one IOMMU group, which can be either assigned to only one VM or to the Proxmox host (containers are part of the host because the share the kernel and memory space), so no.

The problem is, in order to passthrough to the LXC I must disable IOMMU, and to achieve the same with the VM I need to enable IOMMU.

You can switch the PCIe device between VMs and/or the Proxmox host (but never more than one at the same time). However, your specific setup (motherboard and/or (integrated?) graphics) seems to prevent even that.
With Intel integrated graphics, you could try intel_iommu=igfx_off instead of intel_iommu=on which enables IOMMU for everthing but the integrated graphics, but this still won't allow you to use a GPU twice at the same time.