[Bug 1912846] [NEW] Assertion hit on hot-unplugging virtio iommu enabled device

[Eugenio Pérez]

Public bug reported:

>From commit ("2d24a646 device-core: use RCU for
list of children of a bus") an assertion is hit when
removing a iommu aware virtio device, since as->listeners
are not properly removed. To reproduce:

/home/qemu/build/x86_64-softmmu/qemu-system-x86_64 -qmp 
tcp:0:4444,server,nowait ... \
    -netdev tap,id=hostnet0,vhostforce=on,vhost=on \
    -device 
virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:14:18:cc,bus=pci.1,addr=0x0,iommu_platform=on,ats=on

In QMP:
{'execute': 'qmp_capabilities'}
{"execute": "device_del", "arguments": {"id": "net0"} }

And crash:
../softmmu/memory.c:2818: do_address_space_destroy: Assertion 
`QTAILQ_EMPTY(&as->listeners)' failed.

** Affects: qemu
     Importance: Undecided
         Status: New


** Tags: iommu

** Description changed:

  From commit ("2d24a646 device-core: use RCU for
  list of children of a bus") an assertion is hit when
- removing a device, since mr->listeners are not properly
+ removing a device, since as->listeners are not properly
  removed. To reproduce:
  
  /home/qemu/build/x86_64-softmmu/qemu-system-x86_64 -qmp 
tcp:0:4444,server,nowait ... \
-     -netdev tap,id=hostnet0,vhostforce=on,vhost=on \
-     -device 
virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:14:18:cc,bus=pci.1,addr=0x0,iommu_platform=on,ats=on
+     -netdev tap,id=hostnet0,vhostforce=on,vhost=on \
+     -device 
virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:14:18:cc,bus=pci.1,addr=0x0,iommu_platform=on,ats=on
  
  In QMP:
  {'execute': 'qmp_capabilities'}
  {"execute": "device_del", "arguments": {"id": "net0"} }
  
  And crash:
  ../softmmu/memory.c:2818: do_address_space_destroy: Assertion 
`QTAILQ_EMPTY(&as->listeners)' failed.

** Description changed:

  From commit ("2d24a646 device-core: use RCU for
  list of children of a bus") an assertion is hit when
- removing a device, since as->listeners are not properly
- removed. To reproduce:
+ removing a iommu aware virtio device, since as->listeners
+ are not properly removed. To reproduce:
  
  /home/qemu/build/x86_64-softmmu/qemu-system-x86_64 -qmp 
tcp:0:4444,server,nowait ... \
      -netdev tap,id=hostnet0,vhostforce=on,vhost=on \
      -device 
virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:14:18:cc,bus=pci.1,addr=0x0,iommu_platform=on,ats=on
  
  In QMP:
  {'execute': 'qmp_capabilities'}
  {"execute": "device_del", "arguments": {"id": "net0"} }
  
  And crash:
  ../softmmu/memory.c:2818: do_address_space_destroy: Assertion 
`QTAILQ_EMPTY(&as->listeners)' failed.

** Summary changed:

- Assertion hit on hot-unplugging iommu enabled device
+ Assertion hit on hot-unplugging virtio iommu enabled device

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https://bugs.launchpad.net/bugs/1912846

Title:
  Assertion hit on hot-unplugging virtio iommu enabled device

Status in QEMU:
  New

Bug description:
  From commit ("2d24a646 device-core: use RCU for
  list of children of a bus") an assertion is hit when
  removing a iommu aware virtio device, since as->listeners
  are not properly removed. To reproduce:

  /home/qemu/build/x86_64-softmmu/qemu-system-x86_64 -qmp 
tcp:0:4444,server,nowait ... \
      -netdev tap,id=hostnet0,vhostforce=on,vhost=on \
      -device 
virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:14:18:cc,bus=pci.1,addr=0x0,iommu_platform=on,ats=on

  In QMP:
  {'execute': 'qmp_capabilities'}
  {"execute": "device_del", "arguments": {"id": "net0"} }

  And crash:
  ../softmmu/memory.c:2818: do_address_space_destroy: Assertion 
`QTAILQ_EMPTY(&as->listeners)' failed.

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