RE: vfio issue in qemu 2.5

["Goutham GS" <goutham@zadarastorage.com>]

Hello Alex,

Thanks for your quick response.

Unfortunately we are tied to this kernel. Probably we can move to 3.19, if
we are sure of the benefits . Not sure.

Regarding dmesg, there is nothing on the host and the VM never came up to
the point where we could collect dmesg.

Regards,
Goutham.

-----Original Message-----
From: Alex Williamson [mailto:alex.williamson@redhat.com] 
Sent: Thursday, February 4, 2016 10:32 PM
To: Goutham GS <goutham@zadarastorage.com>
Cc: kvm@vger.kernel.org
Subject: Re: vfio issue in qemu 2.5

On Thu, 4 Feb 2016 20:31:17 +0530
"Goutham GS" <goutham@zadarastorage.com> wrote:

> Hi All,
> 
> We are facing a vfio issue on qemu 2.5. Really appreciate any help or 
> pointers. Details are as below:
> 
> We are using qemu 2.5 compiled out of git commit
> 0b0571dd246871f18b7d64b5279511e91e2a7bf6 and are using Linux Kernel
> 3.18.19 for both host and the VM. We are also using KVM VM with 
> pci-assign'ed SRIOV VF interfaces.
> 
> The issue happens once in a while when a running VM is rebooted. On 
> boot, the VM hits the following error and stops.
> 
> qemu-system-x86_64: -device
> vfio-pci,host=04:00.7,id=hostdev2,bus=pci.0,addr=0x9: vfio: failed to 
> set iommu for container: Bad address
> qemu-system-x86_64: -device
> vfio-pci,host=04:00.7,id=hostdev2,bus=pci.0,addr=0x9: vfio: failed to 
> setup container for group 40
> qemu-system-x86_64: -device
> vfio-pci,host=04:00.7,id=hostdev2,bus=pci.0,addr=0x9: vfio: failed to 
> get group 40
> qemu-system-x86_64: -device
> vfio-pci,host=04:00.7,id=hostdev2,bus=pci.0,addr=0x9: Device 
> initialization failed
> 
> Strange thing is, once this error is hit, no further VMs can be 
> spawned on the host and all of them run into the same problem.
> However a reboot of the host appears to solve the issue.
> 
> I have attached the relevant logs.

Is it possible to try a newer kernel on the host?  "Bad address" is -EFAULT,
but I'm not actually able to spot a return path for the VFIO_SET_IOMMU ioctl
that returns -EFAULT.  Is there anything in dmesg when this triggers?
Thanks,

Alex