Re: [Qemu-devel] [Crucial bug] Qemu-2.0.0 do not support virtio-net hot plug/unplug exceed two times

[Gonglei (Arei)]

> >> > > Il 26/04/2014 10:56, Gonglei (Arei) ha scritto:
> >> > > > Public bug reported:
> >> > > >
> >> > > > I want to repeated hot-plug/unplug the virtio-net in the latest qemu
> >> > > upstream
> >> > > > (commit 839a5547574e57cce62f49bfc50fe1f04b00589a), but I am
> failed
> >> at
> >> > > the
> >> > > > second time hot plug the virtio-net to guest.
> >> > > >
> >> > > > Then I tried to use Qemu-2.0.0 release version, but I got the error 
> >> > > > too.
> >> > > >
> >> > > > Cmdline for vm:
> >> > > >
> >> > > > /mnt/sdb/gonglei/qemu/x86_64-softmmu/qemu-system-x86_64
> >> -enable-kvm
> >> > > -m 4096 -smp 4 -name sles-et -boot c -drive
> file=/mnt/sdb/gonglei/image/
> >> > > sles-3.img -vnc 0.0.0.0:10 -monitor stdio
> >> > > > QEMU 1.7.50 monitor - type 'help' for more information
> >> > >
> >> > > For commit 839a5547574e57cce62f49bfc50fe1f04b00589a you should
> have
> >> > > gotten 1.7.90 as the version number.
> >> > >
> >> > Maybe just because Peter Maydell merge remote-tracking branch. But it
> >> doesn't matter.
> >> >
> >> > > > (qemu) device_add virtio-net-pci,id=net1
> >> > > > (qemu) device_del net1
> >> > > > (qemu) device_add virtio-net-pci,id=net1
> >> > > > Duplicate ID 'net1' for device
> >> > > > (qemu)
> >> > >
> >> > > I cannot reproduce this on Fedora running the 2.0.0 package from the
> >> > > virt-preview repository (qemu-system-x86-2.0.0-2.fc20.x86_64).
> >> > >
> >> > > For what it's worth, I get this for --version:
> >> > >
> >> > > $ qemu-system-x86_64 --version
> >> > > QEMU emulator version 2.0.0, Copyright (c) 2003-2008 Fabrice Bellard
> >> > >
> >> > > and likewise, when starting QEMU with "-monitor stdio":
> >> > >
> >> > > QEMU 2.0.0 monitor - type 'help' for more information
> >> > >
> >> > I got the QEMU 2.0.0 version from http://wiki.qemu.org/Download
> >> >
> >> > The issue was reproduced perforce:
> >> > UVP:/mnt/sdb/gonglei/code/qemu-2.0.0/x86_64-softmmu
> >> #./qemu-system-x86_64 -enable-kvm -m 4096 -smp 4 -name sles \
> >> >  -boot c -drive file=/mnt/sdb/gonglei/image/sles-3.img -vnc 0.0.0.0:10
> >> -monitor stdio
> >> > QEMU 2.0.0 monitor - type 'help' for more information
> >> > (qemu) device_add virtio-net-pci,id=net1
> >> > (qemu) device_del net1
> >> > (qemu)  device_add virtio-net-pci,id=net1
> >> > Duplicate ID 'net1' for device
> >> > (qemu)
> >> >
> >> > Anything wrong? Thanks!
> >>
> >> Issue confirmed with both -monitor and qmp-shell with different other
> device
> >> models like e1000.
> >
> > Thanks. This issue confused me two weeks now, any helps will be
> appreciated.
> >
> > Cc'ing Peter and Michael for additional insights.
> 
> I suspect your second device_add fails because the unplug initiated by
> device_del hasn't completed, yet.
> 
> More detailed explanation of the ACPI unplug dance:
> https://lists.nongnu.org/archive/html/qemu-devel/2013-03/msg01362.html
> 
> Please verify the device is gone with "info pci", "info qtree" or
> similar before you try device_del.
> 
Thank you for reply. I have verified it.

Step 1: I executed "device_add virtio-net-pci,id=net1"
with "info pci", I found the net1, showing as below:
Bus  0, device   4, function 0:
    Ethernet controller: PCI device 1af4:1000
      IRQ 0.
      BAR0: I/O at 0xffffffffffffffff [0x001e].
      BAR1: 32 bit memory at 0xffffffffffffffff [0x00000ffe].
      BAR6: 32 bit memory at 0xffffffffffffffff [0x0003fffe].
      id "net1"
Step 2: I executed " device_del net1", but the net1 still existed.

> In QMP, you get a DEVICE_DELETED event when the unplug completes.  See
> qmp/qmp-events.txt. 
Actually, I don't get the event, as the net1 can't be unplug. 

BTW, when I execute step 1 "device_add virtio-net-pci,id=net1", I don't find 
the 
Ethernet controller of virtio-net by "lspci " in the guest OS. 
TBH, the command execution failed despite we can see net1 with "info pci".

Would you help me to verify it? Thanks in advance!

Best regards,
-Gonglei