Re: PCI passthrough

[Alex Williamson <alex.williamson@redhat.com>]

On Mon, 2015-03-16 at 14:35 +0100, shacky wrote:
> Hi.
> I'm using Proxmox VE 3.4 with qemu-server 3.3, and I'm trying to pass
> two PCI-Express AudioScience soundcards to a KVM virtual machine.
> 
> The soundcards are the following:
> 
> ve2:/# lspci
> 03:00.0 PCI bridge: Texas Instruments XIO2000(A)/XIO2200A PCI
> Express-to-PCI Bridge (rev 03)
> 04:00.0 Multimedia audio controller: Texas Instruments TMS320C6414
> TMS320C6415 TMS320C6416
> 05:00.0 PCI bridge: Texas Instruments XIO2000(A)/XIO2200A PCI
> Express-to-PCI Bridge (rev 03)
> 06:00.0 Multimedia audio controller: Texas Instruments TMS320C6414
> TMS320C6415 TMS320C6416
> 
> and I configured the virtual machine in this way:
> 
> machine: q35
> hostpci0: 03:00.0
> hostpci1: 04:00.0
> hostpci2: 05:00.0
> hostpci3: 06:00.0
> 
> But when I try to start the virtual machine I get the following error:
> 
> ve2:/# qm start 202
> kvm: -device pci-assign,host=03:00.0,id=hostpci0,bus=pci.0,addr=0x10:
> Device assignment only supports endpoint assignment, device type 7
> kvm: -device pci-assign,host=03:00.0,id=hostpci0,bus=pci.0,addr=0x10:
> Device initialization failed.
> kvm: -device pci-assign,host=03:00.0,id=hostpci0,bus=pci.0,addr=0x10:
> Device 'kvm-pci-assign' could not be initialized
> 
> I realized that I cannot pass the PCI bridge, so the VM starts passing
> only 04:00.0 and 06:00.0 devices.
> 
> But Alsa on the virtual machine cannot recognise the soundcards, so
> I'm thinking that the problem could be that I'm not passing the PCI
> bridge.

It's never correct to pass the bridge.  Do you get any errors in the
guest when the driver for the sound card is loaded?  Does it work with
440fx machine type (why are you using q35)?  What's the underlying qemu
and kernel version?  Have you tried vfio-pci instead of legacy device
assignment?  Thanks,

Alex