[Qemu-devel] [Bug 1674117] Re: Qemu VM start kills Pulseaudio

[3vIL_VIrUs]

I stumbled across this bug: 
https://bugs.launchpad.net/ubuntu/+source/linux-rt/+bug/367671
Im not sure if that bug relates to this one, but after disabling realtime 
scheduling, pulseaudio does not crash anymore.
However, the lag when starting the VM got significantly worse, the system is 
pretty much unusable the first ~20-30 seconds.

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https://bugs.launchpad.net/bugs/1674117

Title:
  Qemu VM start kills Pulseaudio

Status in QEMU:
  New

Bug description:
  When I start a VM (start command below) in Qemu version >2.5, it kills 
Pulseaudio (paired with a huge lagspike) in ~4/5 cases. Using version 2.5 build 
from GIT, it works fine. This also happens when building from the current GIT 
master (ebedf0f).
  Host:
    Freshly installed Antergos Arch Linux 4.10.3-1-ARCH
    Intel I7-5930K
    ASUS X99 Deluxe II latest UEFI
    GTX 770

  Guest:
    Windows 10 x64
    AMD RX480 via VFIO

  This also happened on my last install (Ubuntu GNOME 16.10).

  Start command:
    QEMU_AUDIO_DRV=pa \
    QEMU_PA_SAMPLES=4096 \
    qemu-system-x86_64 \
      -serial none \
      -parallel none \
      -nodefconfig \
      -nodefaults \
      -name win10 \
      -enable-kvm \
      -cpu host,check,kvm=off \
      -smp 12,sockets=1,cores=6,threads=2 \
      -m 16G \
      -mem-prealloc \
      -device nec-usb-xhci,id=xhci \
      -device usb-host,vendorid=0x05ac,productid=0x0205,bus=xhci.0 \
      -net nic,vlan=0,model=virtio \
      -net bridge,vlan=0,br=bridge0 \
      -object iothread,id=iothread0 \
      -device virtio-blk-pci,iothread=iothread0,drive=drive0 \
      -drive file="$DISK",format=raw,if=none,cache=none,aio=native,id=drive0 \
      -boot order=c,menu=on \
      -rtc base=utc \
      -nographic \
      -k de \
      -monitor stdio \
      -soundhw hda \
      -device vfio-pci,host=02:00.0,addr=09.0,multifunction=on,x-vga=on \
      -device vfio-pci,host=02:00.1,addr=09.1 \
      -device vfio-pci,host=04:00.0,addr=07.0,multifunction=on,id=usbcontroller

  When it kills Pulseaudio, I see these errors in the Qemu console:
    pulseaudio: set_sink_input_volume() failed
    pulseaudio: Reason: Bad state
    pulseaudio: set_sink_input_mute() failed
    pulseaudio: Reason: Bad state
    pulseaudio: set_source_output_volume() failed
    ... many more of these ...

  The journal shows that PulseAudio is killed:
    Mär 19 13:12:42 hp-desktop systemd[530]: pulseaudio.service: Main process 
exited, code=killed, status=9/KILL
    Mär 19 13:12:42 hp-desktop systemd[530]: pulseaudio.service: Unit entered 
failed state.
    Mär 19 13:12:42 hp-desktop systemd[530]: pulseaudio.service: Failed with 
result 'signal'.
    Mär 19 13:12:42 hp-desktop systemd[530]: pulseaudio.service: Service 
hold-off time over, scheduling restart.
    Mär 19 13:12:42 hp-desktop systemd[530]: Stopped Sound Service.
    Mär 19 13:12:42 hp-desktop systemd[530]: Starting Sound Service...

  I've also captured a PulseAudio debug log when this happens, but it
  does not contain anything interesting (no warnings or errors), which
  makes sense in case of SIGKILL.

  In DMESG I get some errors too, but they seem to be just symptoms (but Im 
just guessing...); 00:14.0 is the USB controller my DAC is connected to:
    [ 4372.389051] usb 3-9.4: current rate 4500480 is different from the 
runtime rate 44100
    [ 4372.509163] usb 3-9.4: current rate 4500480 is different from the 
runtime rate 44100
    [ 4372.559104] usb 3-9.4: current rate 4500480 is different from the 
runtime rate 44100
    [ 4373.652557] xhci_hcd 0000:00:14.0: ERROR unknown event type 37
    [ 4373.712382] xhci_hcd 0000:00:14.0: ERROR Transfer event TRB DMA ptr not 
part of current TD ep_index 1 comp_code 36
    [ 4373.715714] xhci_hcd 0000:00:14.0: Looking for event-dma 
0000000745da7f00 trb-start 0000000745da7f10 trb-end 0000000745da7f10 seg-start 
0000000745da7000 seg-end 0000000745da7ff0
    [ 4373.719055] xhci_hcd 0000:00:14.0: ERROR Transfer event TRB DMA ptr not 
part of current TD ep_index 1 comp_code 1
    [ 4373.722381] xhci_hcd 0000:00:14.0: Looking for event-dma 
0000000745da7f00 trb-start 0000000745da7f10 trb-end 0000000745da7f10 seg-start 
0000000745da7000 seg-end 0000000745da7ff0
    [ 4373.725753] xhci_hcd 0000:00:14.0: ERROR Transfer event TRB DMA ptr not 
part of current TD ep_index 4 comp_code 13
    [ 4373.725759] xhci_hcd 0000:00:14.0: Looking for event-dma 
000000073c5a51a0 trb-start 000000073c5a51b0 trb-end 000000073c5a51b0 seg-start 
000000073c5a5000 seg-end 000000073c5a5ff0

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