qemu-system-x86_64 crashed with SIGSEGV in virtio_pci_mask_vq()

[C de-Avillez]

tried to start some VMs today for the Alpha3 testing -- they died with a "kernel: [34396.173557] kvm[16129]: segfault at 10 ip 00007f7e78cdb89e sp 00007f7e6be31ad0 error 4 in qemu-system-x86_64[7f7e78b85000+368000]"; interestingly, apport was not kicked in action.

Tried to start a GDB on a KVM, failed.

Uninstalled PURGE libvirt*, and reinstalled. Run another KVM, and finally I got this bug.

ProblemType: Crash
DistroRelease: Ubuntu 12.10
Package: qemu-kvm 1.1~rc+dfsg-1ubuntu8
ProcVersionSignature: Ubuntu 3.5.0-6.6-generic 3.5.0
Uname: Linux 3.5.0-6-generic x86_64
NonfreeKernelModules: wl
ApportVersion: 2.4-0ubuntu5
Architecture: amd64
Date: Wed Jul 25 19:35:27 2012
ExecutablePath: /usr/bin/qemu-system-x86_64
InstallationMedia: Ubuntu 12.10 "Quantal Quetzal" - Alpha amd64 (20120701)
KvmCmdLine: Error: command ['ps', '-C', 'kvm', '-F'] failed with exit code 1: UID PID PPID C SZ RSS PSR STIME TTY TIME CMD
MachineType: Dell Inc. Latitude E6410
ProcEnviron: PATH=(custom, no user)
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-3.5.0-6-generic root=/dev/mapper/hostname--vg-hostname--root ro
SegvAnalysis:
 Segfault happened at: 0x7f7e78cdb89e <virtio_pci_mask_vq+94>: mov (%r8),%edi
 PC (0x7f7e78cdb89e) ok
 source "(%r8)" (0x00000010) not located in a known VMA region (needed readable region)!
 destination "%edi" ok
 Stack memory exhausted (SP below stack segment)
SegvReason: reading NULL VMA
Signal: 11
SourcePackage: qemu-kvm
StacktraceTop:
 virtio_pci_mask_vq (vector=vector@entry=1, vq=0x7f7e7a00f100, masked=masked@entry=0, dev=<error reading variable: Unhandled dwarf expression opcode 0xfa>) at /build/buildd/qemu-kvm-1.1~rc+dfsg/hw/virtio-pci.c:546
 virtio_pci_mask_notifier (dev=0x7f7e79ff5670, vector=1, masked=0) at /build/buildd/qemu-kvm-1.1~rc+dfsg/hw/virtio-pci.c:576
 msix_set_mask_notifier_for_vector (vector=1, dev=0x7f7e79ff5670) at /build/buildd/qemu-kvm-1.1~rc+dfsg/hw/msix.c:562
 msix_set_mask_notifier (dev=dev@entry=0x7f7e79ff5670, f=f@entry=0x7f7e78cdb930 <virtio_pci_mask_notifier>) at /build/buildd/qemu-kvm-1.1~rc+dfsg/hw/msix.c:577
 virtio_pci_set_guest_notifiers (opaque=0x7f7e79ff5670, assign=true) at /build/buildd/qemu-kvm-1.1~rc+dfsg/hw/virtio-pci.c:651
Title: qemu-system-x86_64 crashed with SIGSEGV in virtio_pci_mask_vq()
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups:

dmi.bios.date: 05/26/2011
dmi.bios.vendor: Dell Inc.
dmi.bios.version: A09
dmi.board.name: 0K42JR
dmi.board.vendor: Dell Inc.
dmi.board.version: A01
dmi.chassis.type: 9
dmi.chassis.vendor: Dell Inc.
dmi.modalias: dmi:bvnDellInc.:bvrA09:bd05/26/2011:svnDellInc.:pnLatitudeE6410:pvr0001:rvnDellInc.:rn0K42JR:rvrA01:cvnDellInc.:ct9:cvr:
dmi.product.name: Latitude E6410
dmi.product.version: 0001
dmi.sys.vendor: Dell Inc.

[Apport retracing service (apport)]

StacktraceTop:
 virtio_pci_mask_vq (vector=vector@entry=1, vq=0x7f7e7a00f100, masked=masked@entry=0, dev=<error reading variable: Unhandled dwarf expression opcode 0xfa>) at /build/buildd/qemu-kvm-1.1~rc+dfsg/hw/virtio-pci.c:546
 virtio_pci_mask_notifier (dev=0x7f7e79ff5670, vector=1, masked=0) at /build/buildd/qemu-kvm-1.1~rc+dfsg/hw/virtio-pci.c:576
 msix_set_mask_notifier_for_vector (vector=1, dev=0x7f7e79ff5670) at /build/buildd/qemu-kvm-1.1~rc+dfsg/hw/msix.c:562
 msix_set_mask_notifier (dev=dev@entry=0x7f7e79ff5670, f=f@entry=0x7f7e78cdb930 <virtio_pci_mask_notifier>) at /build/buildd/qemu-kvm-1.1~rc+dfsg/hw/msix.c:577
 virtio_pci_set_guest_notifiers (opaque=0x7f7e79ff5670, assign=true) at /build/buildd/qemu-kvm-1.1~rc+dfsg/hw/virtio-pci.c:651

[Serge Hallyn (serge-hallyn)]

I'm not getting this on my quantal laptop. Can you tell me what guest you were running, and post the guest xml?

[C de-Avillez (hggdh2)]

Running a quantal server image, already built, with snapshot. The default XML is:

<domain type='kvm'>
  <name>clean-quantal-server-amd64</name>
  <uuid>b9c140ad-ceb8-0829-cdc1-9dfa2b00a5b9</uuid>
  <memory unit='KiB'>524288</memory>
  <currentMemory unit='KiB'>524288</currentMemory>
  <vcpu placement='static'>1</vcpu>
  <os>
    <type arch='x86_64' machine='pc-1.0'>hvm</type>
    <boot dev='cdrom'/>
    <boot dev='hd'/>
    <bootmenu enable='yes'/>
  </os>
  <features>
    <acpi/>
    <apic/>
    <pae/>
  </features>
  <clock offset='utc'/>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>restart</on_crash>
  <devices>
    <emulator>/usr/bin/kvm</emulator>
    <disk type='file' device='disk'>
      <driver name='qemu' type='qcow2' cache='writeback'/>
      <source file='/opt/VM/img/clean-quantal-server-amd64/disk0.qcow2'/>
      <target dev='vda' bus='virtio'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
    </disk>
    <disk type='file' device='cdrom'>
      <driver name='qemu' type='raw'/>
      <target dev='hdc' bus='ide'/>
      <readonly/>
      <address type='drive' controller='0' bus='1' target='0' unit='0'/>
    </disk>
    <controller type='ide' index='0'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/>
    </controller>
    <controller type='usb' index='0'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x2'/>
    </controller>
    <interface type='network'>
      <mac address='52:54:00:b5:86:fb'/>
      <source network='default'/>
      <model type='virtio'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
    </interface>
    <serial type='pty'>
      <target port='0'/>
    </serial>
    <console type='pty'>
      <target type='serial' port='0'/>
    </console>
    <input type='mouse' bus='ps2'/>
    <graphics type='vnc' port='-1' autoport='yes'/>
    <video>
      <model type='cirrus' vram='9216' heads='1'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
    </video>
    <memballoon model='virtio'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
    </memballoon>
  </devices>
</domain>

[Serge Hallyn (serge-hallyn)]

Hm, verified. I'm not sure whether the problem is qcow, or something else in your xml. When I use virt-manager to create a VM it runs fine with quantal server, but using your xml tweaked for my paths, it crashes. Investigating.

[Serge Hallyn (serge-hallyn)]

The problem is introduced by using the pc-1.0 machine type. pc-1.1 seems to work for me.

[Serge Hallyn (serge-hallyn)]

Testing the patches (from upstream) which solved this in Debian.

After a3 closes I will merge the new debian qemu-kvm.

[Serge Hallyn (serge-hallyn)]

This debdiff fixes the issue for me.

[Launchpad Janitor (janitor)]

This bug was fixed in the package qemu-kvm - 1.1~rc+dfsg-1ubuntu9

---------------
qemu-kvm (1.1~rc+dfsg-1ubuntu9) quantal; urgency=low

  [ Michael Tokarev ]
  * added two patches from upstream qemu-kvm/stable-1.1 branch:
    qemu-kvm-Add-missing-default-machine-options.patch
    qemu-kvm-virtio-Do-not-register-mask-notifiers-witho.patch
    (Closes: #679788) (LP: #1029201)

  [ Serge Hallyn ]
  * remove ubuntu/CVE-2011-2212-virtqueue-indirect-overflow.patch
    patch, which was actually fixed in qemu 0.15 by
    "virtio: fix indirect descriptor buffer overflow" (Thanks to
    Michael Tokarev for pointing that out)
 -- Serge Hallyn <email address hidden> Thu, 26 Jul 2012 10:31:53 -0500