Linux USB3.0 PCI-E card dies with IOMMU turned on

[jesterace]

Hi i built a server to help with with my work at home where i can virtualise different OS's for troubleshooting purposes. I pass through multiple PCI-E cards (SAS IT-mode RAID, SCSI controller, Quadro GPU). Those all work just fine in all kinds of guest OS. The host has a Supermicro X8DTL dual socket motherboard, 48GB RAM. I desperately wanted to be able to pass through a USB3.0 PCI-E card so i installed one to try. A cheap VIA controller seemed to work for about 30mins and then dies and won't detect any devices. A Renesas controller just kept randomly hard locking the guest and host (especially if plugging in a external hard disk). Finally i tried an ASMEDIA card and it seemed to last the longest, but after restarting the guest i have to reboot the host. Much like the other cards though, i find that the controller will still randomly die after so long.

 

After much trial and error i followed the solutions of a few forums where it seems that IOMMU is causing lots of issues with USB3. After disabling IOMMU, my problems went away... well at least it worked fine in the host. Obviously turning of IOMMU completely buggered my ability to use passthrough with KVM.

 

Does anyone have any ideas or experience passing through USB3 cards with KVM under linux? Were you successful? Has anyone had the same problems as me?

 

I tried issuing a device /remove and pci bus /reset to see if the card would come alive again without rebooting when it dies, but i just get the following in dmesg:

 

[  +1.740899] xhci_hcd 0000:0a:00.0: ERROR unknown event type 15
[  +5.014832] xhci_hcd 0000:0a:00.0: xHCI host not responding to stop endpoint command.
[  +0.000123] xhci_hcd 0000:0a:00.0: xHCI host controller not responding, assume dead
[  +0.000017] xhci_hcd 0000:0a:00.0: HC died; cleaning up
[  +0.000074] usb usb9-port2: couldn't allocate usb_device
[  +0.000041] usb usb10-port2: couldn't allocate usb_device
 

Many thanks,

James.