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

[Elijah Shakkour]

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. Contact your system 
vendor for further information.
"

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