Re: [Qemu-devel] [PATCH 0/3] VFIO-based PCI device assignment for QEMU 1.2

[Alex Williamson]

On Mon, 2012-08-13 at 17:48 +0200, Andreas Hartmann wrote:
> Alex Williamson wrote:
> > On Mon, 2012-08-13 at 08:27 -0500, Anthony Liguori wrote:
> >> Alex Williamson <address@hidden> writes:
> >>
> >>> VFIO kernel support was just merged into Linux, so I'd like to
> >>> formally propose inclusion of the QEMU vfio-pci driver for
> >>> QEMU 1.2.  Included here is support for x86 PCI device assignment.
> >>> PCI INTx is not yet enabled, but devices making use of either MSI
> >>> or MSI-X work.  The level irqfd and eoifd support I've proposed
> >>> for KVM enable an accelerated patch for this through KVM.  I'd
> >>> like to get this base driver in first and enable the remaining
> >>> support in-tree.
> >>>
> >>> I've split this version up a little from the RFC to make it a bit
> >>> easier to review.  Review comments from Blue Swirl and Avi are
> >>> already incorporated, including Avi's requests to simplify both
> >>> the PCI BAR mapping and unmapping paths.
> >>
> >> Hi Alex,
> >>
> >> Thanks for pushing this forward!  Hopefully this will finally kill
> >> off qemu-kvm.git for good.
> >>
> >> I think this series is going to have to wait for 1.3 to open up.  We
> >> have a very short release window for this release and I'd feel a lot
> >> more comfortable having such a significant feature spend some time in
> >> the development cycle getting testing/review.
> >>
> >> I'd like to see a few Reviewed-by's too for this series before it
> >> goes in.  I expect they won't be hard to get but I also expect it
> >> will take a few more revisions of this series to get there.
> > 
> > That's disappointing, but I can understand your reluctance.  Blue
> > Swirl reviewed the RFC and could perhaps add a Reviewed-by.  Alexey
> > has been working on the POWER port and I'm sure could provide a
> > Reviewed-by.  We also have a few early adopters that are already
> > making use of this code.
> 
> I'm running qemu with vfio patch since Jun 05, 2012
> (awilliam-qemu-vfio-v0.14.0-rc0-6402-g323cf9f.tar.gz). I didn't
> encounter any problem so far.
> 
> If you like, I could compile a more actual version, too (if there have
> been any changes).

The only change in the version proposed for qemu is that legacy
interrupt support has been removed until we can agree on interfaces in
kvm and plumb an EOI path through qemu.  IIRC, the devices you're using
require legacy interrupt support.

> To see more about my use case:
> http://permalink.gmane.org/gmane.linux.drivers.rt2x00.user/1051
> 
> You may add a Tested-by Andreas Hartmann <address@hidden>
> if you like.
> 
> Unfortunately, I'm only running the vfio VM (kvm) with this version of
> qemu, but I'm running parallel 4 other VM's with the unchanged version
> of qemu (kvm-0.15.0-123.2.x86_64), too.
> One of these 4 VM's uses PCIe passthrough.
> 
> I now tried to run all VMs with the new version of qemu. At this point,
> I unfortunately run into a problem with the VM which passes through a
> PCIe device. The error message is (during start of VM):
> 
> virsh start VM
> error: Failed to start domain VM
> error: internal error process exited while connecting to monitor: 
> qemu-system-x86_64: -device 
> pci-assign,host=04:00.0,id=hostdev0,bus=pci.0,addr=0x6: Parameter 'driver' 
> expects device type
> 
> The xml file for libvirt looks like this: 

libvirt doesn't yet support vfio-pci and current qemu.git doesn't yet
support pci-assign.  To use libvirt for device assignment, your only
option right now is to use a qemu-kvm.git based version of qemu.
Thanks,

Alex

> <domain type='kvm'>
>   <name>VM</name>
>   <uuid>44444444-4444-2222-7777-111111111111</uuid>
>   <memory>1048576</memory>
>   <currentMemory>262144</currentMemory>
>   <vcpu>1</vcpu>
>   <os>
>     <type arch='x86_64' machine='pc-0.14'>hvm</type>
>     <boot dev='hd'/>
>   </os>
>   <features>
>     <acpi/>
>     <pae/>
>   </features>
>   <clock offset='utc'/>
>   <on_poweroff>destroy</on_poweroff>
>   <on_reboot>restart</on_reboot>
>   <on_crash>destroy</on_crash>
>   <devices>
>     <emulator>/usr/local/bin/qemu-system-x86_64</emulator>
> 
>     <hostdev mode='subsystem' type='pci' managed='yes'>
>       <source>
>         <address domain='0x0000' bus='0x04' slot='0x00' function='0x0'/>
>       </source>
>     </hostdev>
> 
>     <disk type='file' device='disk'>
>       <source file='/hds/vm.qed' type='aio'/>
>       <target dev='vda' bus='virtio'/>
>       <driver name='qemu' type='qed' cache='none'/>
>     </disk>
> 
>     <input type='mouse' bus='ps2'/>
>     <graphics type='vnc' autoport='yes'/>
>     <video>
>       <model type='cirrus' vram='9216' heads='1'/>
>     </video>
>   </devices>
> </domain>
> 
> 
> Maybe, this is fixed in a newer version of qemu for vfio?
> 
> 
> Thanks,
> kind regards,
> Andreas Hartmann