Re: KVM PCI passthrough IRQ limitations

[Jason Kwon <jkwon@redback.com>]

Chris Wright wrote:
> * Jason Kwon (jkwon@redback.com) wrote:
>> I am attempting to make use of '-pcidevice' on my system, but have run  
>> into some problems.  First, my setup:
>>
>> Fedora 10 x86_64 host system
>> 2.6.28.1-19.fc10 kernel from Koji
>> KVM-84
> 
> You mean both userspace and kernel module built externally?

Yes, I built both from the kvm-84.tar.gz package.

>> % /usr/local/kvm/bin/qemu-system-x86_64 ./vdisk.img -m 384 -pcidevice  
>> host=02:00.0
>> init_assigned_device: Registering real physical device 02:00.0 (bus=2  
>> dev=0 func=0)
>> get_real_device: region 0 size 1024 start 0xe1200000 type 512 resource_fd 12
>> Failed to assign irq for "02:00.0": Input/output error
>> Perhaps you are assigning a device that shares an IRQ with another device?
> 
> any info in dmesg?  what's lspci -t show?

dmesg gives:

pci 0000:02:00.0: PCI INT A -> GSI 16 (level, low) -> IRQ 16
IRQ handler type mismatch for IRQ 16
current handler: uhci_hcd:usb3
Pid: 3597, comm: qemu-system-x86 Not tainted 2.6.28.1-19.fc10.x86_64 #1
Call Trace:
  [<ffffffff810891f6>] __setup_irq+0x1f4/0x227
  [<ffffffffa01bc917>] ? kvm_assigned_dev_intr+0x0/0x2c [kvm]
  [<ffffffff810892fc>] request_irq+0xd3/0x15a
  [<ffffffffa01bc9d2>] assigned_device_update_intx+0x8f/0xa9 [kvm]
  [<ffffffffa01be711>] kvm_vm_ioctl+0x6af/0x79c [kvm]
  [<ffffffff8114d9bf>] ? inode_has_perm+0x5b/0x61
  [<ffffffff81051241>] ? __sigqueue_free+0x38/0x3c
  [<ffffffff81051f39>] ? __dequeue_signal+0x103/0x12f
  [<ffffffff810d82ec>] vfs_ioctl+0x2a/0x78
  [<ffffffff810d86cc>] do_vfs_ioctl+0x392/0x3c0
  [<ffffffff810d874f>] sys_ioctl+0x55/0x77
  [<ffffffff8101106a>] system_call_fastpath+0x16/0x1b
kvm: failed to enable INTx device!
pci 0000:02:00.0: PCI INT A disabled

lspci -t shows:

-[0000:00]-+-00.0
            +-01.0-[0000:01]--
            +-03.0-[0000:02]----00.0
            +-07.0-[0000:03]--
            +-10.0
            +-10.1
            +-14.0
            +-14.1
            +-14.2
            +-14.3
            +-19.0
            +-1a.0
            +-1a.1
            +-1a.2
            +-1a.7
            +-1b.0
            +-1c.0-[0000:04]--
            +-1c.1-[0000:05]--
            +-1c.4-[0000:06]----00.0
            +-1d.0
            +-1d.1
            +-1d.2
            +-1d.7
            +-1e.0-[0000:07]--+-02.0
            |                 \-03.0
            +-1f.0
            +-1f.2
            +-1f.3
            \-1f.5

Thanks,

Jason