Already assigned devices should not be listed as "available" under VM Settings > Devices of other VMs

[mfc]

reproduce by assigning devices to a VM (say the USB devices to the default sys-usb). Go to VM Settings > Devices of another VM. Those controllers should not be assignable to other VMs.

Reported at the Internet Freedom Festival.

[marmarek]

I agree those devices shouldn't be listed in Qubes Manager. Also it would be good idea to exclude system critical components (host bridge, PCI bridge, primary SATA controller etc).
But there are some cases when assigning the same device to multiple VMs makes sense - for example you may have alternative USB VM used only for video chats (as it isn't currently possible to attach single USB device to another VM). Of course you can't run both of them at the same time, but still should be possible. IMHO leaving this option only from qvm-pci command line tool is good enough.

[marmarek]

I agree those devices shouldn't be listed in Qubes Manager. Also it would be good idea to exclude system critical components (host bridge, PCI bridge, primary SATA controller etc).
But there are some cases when assigning the same device to multiple VMs makes sense - for example you may have alternative USB VM used only for video chats (as it isn't currently possible to attach single USB device to another VM). Of course you can't run both of them at the same time, but still should be possible. IMHO leaving this option only from qvm-pci command line tool is good enough.

[bnvk]

The case @mfc brings up here, I have run into and it failed in a confusing and less than ideal way. Ironically, this case came up, because I was trying to do what @marmarek mentions

But there are some cases when assigning the same device to multiple VMs makes sense

I'll think about if there is a better way to handle this in the new Qubes Manager I'm working on!

[bnvk]

The case @mfc brings up here, I have run into and it failed in a confusing and less than ideal way. Ironically, this case came up, because I was trying to do what @marmarek mentions

But there are some cases when assigning the same device to multiple VMs makes sense

I'll think about if there is a better way to handle this in the new Qubes Manager I'm working on!