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Bug 924164 - qemu-kvm segmentation fault when enable multifunction, assign two NIC cards to guest, hot unplug one nic card, run system_reset.
Summary: qemu-kvm segmentation fault when enable multifunction, assign two NIC cards t...
Keywords:
Status: CLOSED CURRENTRELEASE
Alias: None
Product: Red Hat Enterprise Linux 7
Classification: Red Hat
Component: qemu-kvm
Version: 7.0
Hardware: x86_64
OS: Linux
medium
medium
Target Milestone: rc
: ---
Assignee: Alex Williamson
QA Contact: Virtualization Bugs
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2013-03-21 10:19 UTC by huiqingding
Modified: 2014-07-17 12:56 UTC (History)
9 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Environment:
Last Closed: 2014-07-17 12:56:36 UTC
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)

Description huiqingding 2013-03-21 10:19:44 UTC 
Description of problem:

Enable multifunction, assign two NIC cards to guest, hot unplug one nic card, run system_reset. qemu-kvm segmentation fault.

Version-Release number of selected component (if applicable):
# uname -r
3.8.0-0.40.el7.x86_64
# uname -r
# rpm -qa | grep qemu-kvm
qemu-kvm-1.4.0-1.el7.x86_64

How reproducible:
100%

Steps to Reproduce:
1. Enable multifunction, assign two NIC cards to guest and boot the guest:
/usr/libexec/qemu-kvm -M pc-1.3 -cpu SandyBridge -enable-kvm -m 2048 -smp 2,sockets=1,cores=2,threads=1 -name rhel7 -uuid 6afa5f93-2d4f-420f-81c6-e5fdddbd1c83 -drive file=/dev/sdb,if=none,id=drive-virtio-disk0,format=qcow2,serial=40c061dd-5d60-4fc5-865f-55db700407f0,cache=none,werror=stop,rerror=stop,aio=threads -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x5,drive=drive-virtio-disk0,id=virtio-disk0 -netdev tap,id=hostnet0,vhost=on -device pci-assign,host=00:19.0,multifunction=on,addr=8.0,id=h2guest_nic_1 -device pci-assign,host=04:00.1,addr=8.1,id=h2guest_nic_2 -vnc :1 -qmp tcp:0:4445,server,nowait -monitor stdio

2. On guest, use "lspci" to check NIC card
# lspci | grep Ethernet

2. Hot unplug one NIC card
{"execute":"device_del","arguments":{"id":"h2guest_nic_2"}}

3. On guest, use "lspci" to check NIC card
# lspci | grep Ethernet

4. On host, run system_reset
{"execute":"system_reset"}}

Actual results:
After step4, qemu-kvm segmentation fault

Expected results:
After step4, guest can be rebooted.

Additional info:
(gdb) bt
#0  0x00007ffff2c20e50 in __memcmp_sse4_1 () from /lib64/libc.so.6
#1  0x0000555555793f92 in patch_hypercalls (s=0x55555669e9d0) at /usr/src/debug/qemu-1.4.0/hw/kvmvapic.c:544
#2  vapic_prepare (s=s@entry=0x55555669e9d0) at /usr/src/debug/qemu-1.4.0/hw/kvmvapic.c:609
#3  0x0000555555794316 in vapic_write (opaque=0x55555669e9d0, addr=<optimized out>, data=<optimized out>, size=<optimized out>) at /usr/src/debug/qemu-1.4.0/hw/kvmvapic.c:646
#4  0x00005555557c2942 in access_with_adjusted_size (addr=addr@entry=0, value=value@entry=0x7fffe7dfdae8, size=2, access_size_min=<optimized out>, access_size_max=<optimized out>, 
    access=access@entry=0x5555557c2f60 <memory_region_write_accessor>, opaque=opaque@entry=0x5555566a0cf8) at /usr/src/debug/qemu-1.4.0/memory.c:364
#5  0x00005555557c3fb7 in memory_region_iorange_write (iorange=<optimized out>, offset=0, width=2, data=32) at /usr/src/debug/qemu-1.4.0/memory.c:439
#6  0x00005555557c0d85 in kvm_handle_io (count=1, size=2, direction=1, data=<optimized out>, port=126) at /usr/src/debug/qemu-1.4.0/kvm-all.c:1429
#7  kvm_cpu_exec (env=env@entry=0x5555566852d0) at /usr/src/debug/qemu-1.4.0/kvm-all.c:1581
#8  0x000055555576a871 in qemu_kvm_cpu_thread_fn (arg=0x5555566852d0) at /usr/src/debug/qemu-1.4.0/cpus.c:759
#9  0x00007ffff6487d15 in start_thread () from /lib64/libpthread.so.0
#10 0x00007ffff2bb746d in clone () from /lib64/libc.so.6
Comment 2 Hai Huang 2013-03-22 14:27:01 UTC 
Similar to BZ 924099, may not be a valid test case:
attempting to hot-unplug a pci-assigned device.

Please confirm and dispose appropriately.  Thanks.
Comment 4 Ronen Hod 2014-07-13 13:56:07 UTC 
1. Not clear if the test case is valid
2. Reassigning to Alex, since it is about PCI assignment
3. Worth rechecking in 7.1 (Is it VFIO only?)
Comment 5 Alex Williamson 2014-07-13 15:38:07 UTC 
Please re-test, hot unplug of a single function of a multifunction device should not be allowed.
Comment 6 huiqingding 2014-07-17 07:57:44 UTC 
(In reply to Alex Williamson from comment #5)
> Please re-test, hot unplug of a single function of a multifunction device
> should not be allowed.

Hi, Alex,

I re-test this issue using the following version:
kernel-3.10.0-123.6.3.el7.x86_64
qemu-kvm-1.5.3-66.el7.x86_64

Use multifunction=on, asssign two functions of a device to the guest, when hot unplug a single function, two functions of the device will be removed.

Steps to test:
1. boot a guest and assign two functions with "multifunction=on"  
# /usr/libexec/qemu-kvm -M pc -enable-kvm -m 2048 -smp 2,sockets=1,cores=2,threads=1 -name rhel7 -uuid 6afa5f93-2d4f-420f-81c6-e5fdddbd1c83 -drive file=/home/huding/rhel7-test.qcow2,if=none,id=drive-virtio-disk0,format=qcow2,serial=40c061dd-5d60-4fc5-865f-55db700407f0,cache=none,werror=stop,rerror=stop,aio=threads -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x5,drive=drive-virtio-disk0,id=virtio-disk0 -device vfio-pci,host=01:00.0,id=h2guest_nic_1,multifunction=on,addr=8.0 -device vfio-pci,host=01:00.1,id=h2guest_nic_2,addr=8.1 -vnc :1 -qmp tcp:0:4445,server,nowait -monitor stdio

2. use "info pci" to check the assigned device

3. hot unplug a single function
{"execute":"device_del","arguments":{"id":"h2guest_nic_2"}}
{"return": {}}
{"timestamp": {"seconds": 1405581765, "microseconds": 929385}, "event": "DEVICE_DELETED", "data": {"device": "h2guest_nic_2", "path": "/machine/peripheral/h2guest_nic_2"}}
{"timestamp": {"seconds": 1405581766, "microseconds": 161433}, "event": "DEVICE_DELETED", "data": {"device": "h2guest_nic_1", "path": "/machine/peripheral/h2guest_nic_1"}}

4. use "info pci" to check the assigned device

5. run "system_reset"

Actual results:
after step2, two functions can be found as following:
  Bus  0, device   8, function 0:
    Ethernet controller: PCI device 8086:1528
      IRQ 11.
      BAR0: 64 bit prefetchable memory at 0xfe000000 [0xfe1fffff].
      BAR4: 64 bit prefetchable memory at 0xfe400000 [0xfe403fff].
      BAR6: 32 bit memory at 0xffffffffffffffff [0x0007fffe].
      id "h2guest_nic_1"
  Bus  0, device   8, function 1:
    Ethernet controller: PCI device 8086:1528
      IRQ 10.
      BAR0: 64 bit prefetchable memory at 0xfe200000 [0xfe3fffff].
      BAR4: 64 bit prefetchable memory at 0xfe404000 [0xfe407fff].
      BAR6: 32 bit memory at 0xffffffffffffffff [0x0007fffe].
      id "h2guest_nic_2"
after step4, two functions are all removed.
after step5, the guest can reboot normally.
Comment 7 Alex Williamson 2014-07-17 12:56:36 UTC 
Thanks for the re-test, it appears to function as expected.
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