Re: [Qemu-devel] Question: SRIOV support over Win Hyper-V VM running in QEMU process on Linux host

["Michael S. Tsirkin" <mst@redhat.com>]

On Thu, Jul 26, 2018 at 07:34:41PM +0300, Marcel Apfelbaum wrote:
> 
> 
> On 07/26/2018 07:14 PM, Michael S. Tsirkin wrote:
> > On Thu, Jul 26, 2018 at 06:51:13PM +0300, Marcel Apfelbaum wrote:
> > > Hi
> > > 
> > > On 07/26/2018 05:52 PM, Stefan Hajnoczi wrote:
> > > > On Thu, Jul 12, 2018 at 07:33:14AM +0000, Elijah Shakkour wrote:
> > > > > Hey,
> > > > > 
> > > > > Our team is adding a NIC functional  emulation to QEMU.
> > > > > One of the features we are adding to this NIC is SRIOV.
> > > > > 
> > > > > Here is the error message I get when checking SRIOV support of  our emulated NIC on Win2016 server (the hyper-v VM).
> > > > > "
> > > > > SR-IOV cannot be used on this system as the PCI Express hardware does not support Access Control Services (ACS) at any root port.
> > > QEMU's emulated PCI Express Root Ports do not support ACS yet, however I am
> > > not sure ACS is a prerequisite
> > > for SR-IOV.
> > Looks like windows blocks dev assignment in nested VMs without it.
> > Thinking about it, doesn't vfio do the same by default?
> vfio requires vIOMMU even for nested, as far as I know.

Absolutely.

> They do have a
> "no-iommu"
> option, but I don't know how  it can help in this case.
> 
> Elijah, what about implementing ACS for QEMU's generic PCIe Root Ports?
> Maybe is not too complicated and it seems like a handy feature to have
> anyway.
> Patches would be welcomed :)
> 
> Thanks,
> Marcel
> 
> >   I think vfio has
> > a flag to override this though.
> > 
> > > We would need ARI support for allowing more than 8VFs, but QEMU
> > > doesn't support that either (yet).
> > > 
> > > Knut Omag has some working patches, he successfully implemented SR-IOV with
> > > QEMU, see:
> > >       https://github.com/knuto/qemu/tree/sriov_patches_v7
> > > 
> > > The code was not merged since we need at least a device with SR-IOV support
> > > to justify the addition.
> > > 
> > > > > Contact your system vendor for further information.
> > > > > "
> > > > I'm not sure what the status of emulated SR-IOV is so I have CCed
> > > > Michael Tsirkin and Marcel Apfelbaum, the PCI maintainers in QEMU.
> > > Thanks,
> > > Marcel
> > > 
> > > > > Could you please advise about what could be the issue here?
> > > > > 
> > > > > BTW: I use same configuration (VM XML file attached) when running linux VM (RH7.2) image (instead of Win Hyper-V) over the same host and SRIOV is working for me there.
> > > > > 
> > > > > Here the XML file I use to define the VM (our emulated NIC is added at the end of XML):
> > > > > "
> > > > > <domain type='kvm' xmlns:qemu='http://libvirt.org/schemas/domain/qemu/1.0'>
> > > > >     <name>nst105</name>
> > > > >     <uuid>0249a525-2ee2-432b-a1f5-a6db83b089a3</uuid>
> > > > >     <memory unit='KiB'>8388608</memory>
> > > > >     <currentMemory unit='KiB'>8388608</currentMemory>
> > > > >     <vcpu placement='static'>8</vcpu>
> > > > >     <resource>
> > > > >       <partition>/machine</partition>
> > > > >     </resource>
> > > > >     <os>
> > > > >       <type arch='x86_64' machine='pc-q35-2.11'>hvm</type>
> > > > >     </os>
> > > > >     <features>
> > > > >       <acpi/>
> > > > >       <apic/>
> > > > >       <hyperv>
> > > > >         <relaxed state='on'/>
> > > > >         <vapic state='on'/>
> > > > >         <spinlocks state='on' retries='8191'/>
> > > > >       </hyperv>
> > > > >     </features>
> > > > >     <cpu mode='custom' match='exact' check='none'>
> > > > >       <model fallback='forbid'>SandyBridge</model>
> > > > >       <feature policy='require' name='hypervisor'/>
> > > > >       <feature policy='require' name='vmx'/>
> > > > >     </cpu>
> > > > >     <clock offset='localtime'>
> > > > >       <timer name='rtc' tickpolicy='catchup'/>
> > > > >       <timer name='pit' tickpolicy='delay'/>
> > > > >       <timer name='hpet' present='no'/>
> > > > >       <timer name='hypervclock' present='yes'/>
> > > > >     </clock>
> > > > >     <on_poweroff>destroy</on_poweroff>
> > > > >     <on_reboot>restart</on_reboot>
> > > > >     <on_crash>destroy</on_crash>
> > > > >     <pm>
> > > > >       <suspend-to-mem enabled='no'/>
> > > > >       <suspend-to-disk enabled='no'/>
> > > > >     </pm>
> > > > >     <devices>
> > > > >       <emulator>/opt/qemu/bin/qemu-system-x86_64</emulator>
> > > > >       <disk type='file' device='disk'>
> > > > >         <driver name='qemu' type='qcow2'/>
> > > > >         <source file='/images/nst105.qcow2'/>
> > > > >         <target dev='sda' bus='sata'/>
> > > > >         <boot order='2'/>
> > > > >         <address type='drive' controller='0' bus='0' target='0' unit='0'/>
> > > > >       </disk>
> > > > >       <controller type='usb' index='0' model='ich9-ehci1'>
> > > > >         <address type='pci' domain='0x0000' bus='0x00' slot='0x1d' function='0x7'/>
> > > > >       </controller>
> > > > >       <controller type='usb' index='0' model='ich9-uhci1'>
> > > > >         <master startport='0'/>
> > > > >         <address type='pci' domain='0x0000' bus='0x00' slot='0x1d' function='0x0' multifunction='on'/>
> > > > >       </controller>
> > > > >       <controller type='usb' index='0' model='ich9-uhci2'>
> > > > >         <master startport='2'/>
> > > > >         <address type='pci' domain='0x0000' bus='0x00' slot='0x1d' function='0x1'/>
> > > > >       </controller>
> > > > >       <controller type='usb' index='0' model='ich9-uhci3'>
> > > > >         <master startport='4'/>
> > > > >         <address type='pci' domain='0x0000' bus='0x00' slot='0x1d' function='0x2'/>
> > > > >       </controller>
> > > > >       <controller type='sata' index='0'>
> > > > >         <address type='pci' domain='0x0000' bus='0x00' slot='0x1f' function='0x2'/>
> > > > >       </controller>
> > > > >       <controller type='pci' index='0' model='pcie-root'/>
> > > > >       <controller type='pci' index='1' model='pcie-root-port'>
> > > > >         <model name='pcie-root-port'/>
> > > > >         <target chassis='1' port='0x10'/>
> > > > >         <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0' multifunction='on'/>
> > > > >       </controller>
> > > > >       <controller type='pci' index='2' model='pcie-root-port'>
> > > > >         <model name='pcie-root-port'/>
> > > > >         <target chassis='2' port='0x11'/>
> > > > >         <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x1'/>
> > > > >       </controller>
> > > > >       <controller type='pci' index='3' model='pcie-root-port'>
> > > > >         <model name='pcie-root-port'/>
> > > > >         <target chassis='3' port='0x12'/>
> > > > >         <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x2'/>
> > > > >       </controller>
> > > > >       <controller type='pci' index='4' model='dmi-to-pci-bridge'>
> > > > >         <model name='i82801b11-bridge'/>
> > > > >         <address type='pci' domain='0x0000' bus='0x00' slot='0x1e' function='0x0'/>
> > > > >       </controller>
> > > > >       <controller type='pci' index='5' model='pci-bridge'>
> > > > >         <model name='pci-bridge'/>
> > > > >         <target chassisNr='5'/>
> > > > >         <address type='pci' domain='0x0000' bus='0x04' slot='0x00' function='0x0'/>
> > > > >       </controller>
> > > > >       <interface type='bridge'>
> > > > >         <mac address='00:50:56:1b:dd:6f'/>
> > > > >         <source bridge='br0'/>
> > > > >         <model type='virtio'/>
> > > > >         <boot order='1'/>
> > > > >         <address type='pci' domain='0x0000' bus='0x01' slot='0x00' function='0x0'/>
> > > > >       </interface>
> > > > >       <serial type='pty'>
> > > > >         <target port='0'/>
> > > > >       </serial>
> > > > >       <console type='pty'>
> > > > >         <target type='serial' port='0'/>
> > > > >       </console>
> > > > >       <input type='tablet' bus='usb'>
> > > > >         <address type='usb' bus='0' port='1'/>
> > > > >       </input>
> > > > >       <input type='mouse' bus='ps2'/>
> > > > >       <input type='keyboard' bus='ps2'/>
> > > > >       <graphics type='vnc' port='-1' autoport='yes' listen='127.0.0.1' keymap='en-us'>
> > > > >         <listen type='address' address='127.0.0.1'/>
> > > > >       </graphics>
> > > > >       <video>
> > > > >         <model type='vga' vram='16384' heads='1' primary='yes'/>
> > > > >         <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x0'/>
> > > > >       </video>
> > > > >       <memballoon model='virtio'>
> > > > >         <address type='pci' domain='0x0000' bus='0x02' slot='0x00' function='0x0'/>
> > > > >       </memballoon>
> > > > >     </devices>
> > > > >     <seclabel type='none' model='none'/>
> > > > >     <seclabel type='dynamic' model='dac' relabel='yes'/>
> > > > >     <qemu:commandline>
> > > > >       <qemu:arg value='-device'/>
> > > > >       <qemu:arg value='pcie-root-port,pref64-reserve=500M,slot=0,id=pcie_port.1'/>
> > > > >       <qemu:arg value='-netdev'/>
> > > > >       <qemu:arg value='tap,id=tap5,ifname=tap5,script=no,downscript=no'/>
> > > > >       <qemu:arg value='-device'/>
> > > > >       <qemu:arg value='my_emu_nic,netdev=tap5,bus=pcie_port.1'/>
> > > > >     </qemu:commandline>
> > > > > </domain>
> > > > > "
> > > > > ______________________
> > > > > General info:
> > > > > Host OS: RH7.0 (Kernel: 4.14.13)
> > > > > QEMU version: 2.11
> > > > > libvirt version: 3.2.0
> > > > > Running the following on the host shows that both nested and IOMMU are
> > > > > enabled:
> > > > > ~]#: cat /sys/module/kvm_intel/parameters/nested
> > > > > Y
> > > > > ~]# dmesg | grep -e DMAR -e IOMMU
> > > > > [    0.000000] DMAR: IOMMU enabled
> > > > > 
> > > > > Thanks,
> > > > > Elijah
> > > > >