[Qemu-devel] [Bug 1422285] Re: The guest will be destroyed when hot plug the VF to guest for the second time.

[chao zhou]

the first bad commit is:
commit ec6f25e788ef57ce1e9f734984ef8885172fd9e2
Merge: 007c99f 9ef1473
Author: Peter Maydell <address@hidden>
Date:   Tue Feb 3 21:37:16 2015 +0000

    Merge remote-tracking branch 'remotes/rth/tags/pull-tg-s390-20150203' into 
staging
    
    s390 translator bug fixes
    
    # gpg: Signature made Tue 03 Feb 2015 20:39:15 GMT using RSA key ID 4DD0279B
    # gpg: Good signature from "Richard Henderson <address@hidden>"
    # gpg:                 aka "Richard Henderson <address@hidden>"
    # gpg:                 aka "Richard Henderson <address@hidden>"
    
    * remotes/rth/tags/pull-tg-s390-20150203:
      target-s390x: fix and optimize slb* and slbg* computation of carry/borrow 
flag
      target-s390x: support OC and NC in the EX instruction
      disas/s390.c: Remove unused variables
      target-s390x: Mark check_privileged() as !CONFIG_USER_ONLY
      target-s390: Implement ECAG
      target-s390: Implement LURA, LURAG, STURG
      target-s390: Fix STURA
      target-s390: Fix STIDP
      target-s390: Implement EPSW
      target-s390: Implement SAM specification exception
    
    Signed-off-by: Peter Maydell <address@hidden>

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https://bugs.launchpad.net/bugs/1422285

Title:
  The guest will be destroyed when hot plug the VF to guest for the
  second time.

Status in QEMU:
  New

Bug description:
  Environment:
  ------------
  Host OS (ia32/ia32e/IA64):ia32e
  Guest OS (ia32/ia32e/IA64):ia32e
  Guest OS Type (Linux/Windows):linux
  kvm.git Commit: 6557bada461afeaa920a189fae2cff7c8fdce39f
  qemu.kvm Commit: cd2d5541271f1934345d8ca42f5fafff1744eee7
  Host Kernel Version:3.19.0-rc3
  Hardware:Haswell_EP,Ivytown_EP

  
  Bug detailed description:
  --------------------------
  create guest , then hot plug the VF to the guest for the second time, the 
guest will be destroyed.

  note:
  1. hot plug the device to guest with vfio, the guest works fine
  2.this should be a qemu bug:
  kvm      +  qemu     = result
  6557bada +  cd2d5541 = bad
  6557bada +  a805ca54 = good

  
  Reproduce steps:
  ----------------
  1. qemu-system-x86_64 -enable-kvm -m 2G -net none -monitor pty rhel6u5.qcow
  2. echo "device_add pci-assign,host=03:10.1,id=nic" >/dev/pts/2
  3. cat /dev/pts/2 &
  4. echo "device_del nic" >/dev/pts/2
  5. echo "device_add pci-assign,host=03:10.0,id=nic" >/dev/pts/2

  Current result:
  ----------------
  guest will be destroyed when hot plug the vf to guest for the second time.

  Expected result:
  ----------------
  guest works fine when hot plug the vf to guest for the second time

  Basic root-causing log:
  ----------------------
  address@hidden cathy]# qemu-system-x86_64 -enable-kvm -m 2G -net none 
-monitor pty rhel6u5.qcow 
  char device redirected to /dev/pts/2 (label compat_monitor0)
  Segmentation fault (core dumped)

  
  some dmesg log:

  pci-stub 0000:03:10.1: kvm deassign device
  pci-stub 0000:03:10.1: enabling device (0000 -> 0002)
  qemu-system-x86[9894]: segfault at 0 ip           (null) sp 00007fa73df0cae8 
error 14
  pci-stub 0000:03:10.1: kvm assign device

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