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Bug 801160 - managedsave+restart of <cpu mode='host-model'> VM crashes libvirtd
Summary: managedsave+restart of <cpu mode='host-model'> VM crashes libvirtd
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 6
Classification: Red Hat
Component: libvirt
Version: 6.3
Hardware: Unspecified
OS: Unspecified
unspecified
unspecified
Target Milestone: rc
: ---
Assignee: Jiri Denemark
QA Contact: Virtualization Bugs
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2012-03-07 19:43 UTC by Eduardo Habkost
Modified: 2012-06-20 06:49 UTC (History)
9 users (show)

Fixed In Version: libvirt-0.9.10-5.el6
Doc Type: Bug Fix
Doc Text:
Clone Of:
Environment:
Last Closed: 2012-06-20 06:49:46 UTC
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2012:0748 0 normal SHIPPED_LIVE Low: libvirt security, bug fix, and enhancement update 2012-06-19 19:31:38 UTC

Description Eduardo Habkost 2012-03-07 19:43:48 UTC 
Description of problem:
When using 'virsh managedsave' followed by 'virsh start' of a <cpu mode='host-model'> virtual machine, libvirtd crashes inside x86ModelFind().


Version-Release number of selected component (if applicable):
libvirt-0.9.10-4.el6.x86_64

How reproducible:
Always.

Steps to Reproduce:

# cat crash-libvirt.sh
cat > /tmp/crashvm.xml <<EOF
<domain type='kvm'>
  <name>crashvm</name>
  <memory>1048576</memory>
  <currentMemory>1048576</currentMemory>
  <vcpu>16</vcpu>
  <os>
    <type arch='x86_64' machine='pc'>hvm</type>
  </os>
  <features>
    <acpi/>
    <apic/>
    <pae/>
  </features>
  <cpu mode='host-model' match='exact'>
    <model fallback='forbid'/>
    <topology sockets='2' cores='4' threads='2'/>
  </cpu>
  <clock offset='utc'/>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>restart</on_crash>
</domain>
EOF
virsh define /tmp/crashvm.xml
virsh start crashvm
virsh managedsave crashvm
virsh start crashvm
# 
# sh -x crash-libvirt.sh
+ cat
+ virsh define /tmp/crashvm.xml
Domain crashvm defined from /tmp/crashvm.xml

+ virsh start crashvm
Domain crashvm started

+ virsh managedsave crashvm

Domain crashvm state saved by libvirt

+ virsh start crashvm
error: Failed to start domain crashvm
error: End of file while reading data: Input/output error

# 


Additional info:
I couldn't reproduce it on Fedora 16, using libvirt-0.9.6-4.fc16.x86_64.

gdb backtrace:

Program received signal SIGSEGV, Segmentation fault.  
[Switching to Thread 0x7f956298d700 (LWP 8093)]
0x00000030437249ea in __strcmp_sse42 () from /lib64/libc.so.6
(gdb) up
#1  0x00007f95688e8871 in x86ModelFind (cpu=0x7f954c000fe0, map=0x7f954c000ae0, policy=1) at cpu/cpu_x86.c:791
791             if (STREQ(model->name, name))
(gdb) p name
$1 = 0x0
(gdb) up
#2  x86ModelFromCPU (cpu=0x7f954c000fe0, map=0x7f954c000ae0, policy=1) at cpu/cpu_x86.c:810
810             if ((model = x86ModelFind(map, cpu->model)) == NULL) {
(gdb) p cpu->model
$2 = 0x0

(gdb) bt
#0  0x00000030437249ea in __strcmp_sse42 () from /lib64/libc.so.6
#1  0x00007f95688e8871 in x86ModelFind (cpu=0x7f954c000fe0, map=0x7f954c000ae0, policy=1) at cpu/cpu_x86.c:791
#2  x86ModelFromCPU (cpu=0x7f954c000fe0, map=0x7f954c000ae0, policy=1) at cpu/cpu_x86.c:810
#3  0x00007f95688e9215 in x86Compute (host=<value optimized out>, cpu=0x7f954c000fe0, guest=0x7f956298beb0) at cpu/cpu_x86.c:1164
#4  0x0000000000475800 in qemuBuildCpuArgStr (conn=0x7f952c000bd0, driver=0x7f9554007280, def=0x7f954c009e10, monitor_chr=0x7f954c005ec0, monitor_json=true, qemuCaps=0x7f954c005f10, 
    migrateFrom=0x4f3343 "stdio", migrateFd=20, snapshot=0x0, vmop=VIR_NETDEV_VPORT_PROFILE_OP_RESTORE) at qemu/qemu_command.c:3677
#5  qemuBuildCommandLine (conn=0x7f952c000bd0, driver=0x7f9554007280, def=0x7f954c009e10, monitor_chr=0x7f954c005ec0, monitor_json=true, qemuCaps=0x7f954c005f10, migrateFrom=0x4f3343 "stdio", 
    migrateFd=20, snapshot=0x0, vmop=VIR_NETDEV_VPORT_PROFILE_OP_RESTORE) at qemu/qemu_command.c:4009
#6  0x000000000048ca06 in qemuProcessStart (conn=0x7f952c000bd0, driver=0x7f9554007280, vm=0x7f9544001570, migrateFrom=0x4f3343 "stdio", start_paused=true, autodestroy=false, stdin_fd=20, 
    stdin_path=0x7f954c000b30 "/var/lib/libvirt/qemu/save/crashvm.save", snapshot=0x0, vmop=VIR_NETDEV_VPORT_PROFILE_OP_RESTORE) at qemu/qemu_process.c:3294
#7  0x000000000045dc1e in qemuDomainSaveImageStartVM (conn=0x7f952c000bd0, driver=0x7f9554007280, vm=0x7f9544001570, fd=0x7f956298c93c, header=0x7f956298c940, 
    path=0x7f954c000b30 "/var/lib/libvirt/qemu/save/crashvm.save", start_paused=false) at qemu/qemu_driver.c:4118
#8  0x000000000045e1d0 in qemuDomainObjRestore (conn=0x7f952c000bd0, driver=0x7f9554007280, vm=0x7f9544001570, flags=0) at qemu/qemu_driver.c:4406
#9  qemuDomainObjStart (conn=0x7f952c000bd0, driver=0x7f9554007280, vm=0x7f9544001570, flags=0) at qemu/qemu_driver.c:4708
#10 0x000000000045e862 in qemuDomainStartWithFlags (dom=0x7f954c0008c0, flags=0) at qemu/qemu_driver.c:4777
#11 0x00007f956890feb6 in virDomainCreate (domain=0x7f954c0008c0) at libvirt.c:8062
#12 0x0000000000439292 in remoteDispatchDomainCreate (server=<value optimized out>, client=<value optimized out>, msg=<value optimized out>, rerr=0x7f956298cbc0, args=<value optimized out>, 
    ret=<value optimized out>) at remote_dispatch.h:852
#13 remoteDispatchDomainCreateHelper (server=<value optimized out>, client=<value optimized out>, msg=<value optimized out>, rerr=0x7f956298cbc0, args=<value optimized out>, 
    ret=<value optimized out>) at remote_dispatch.h:830
#14 0x00007f956894f1f5 in virNetServerProgramDispatchCall (prog=0x14cfe00, server=0x14c4ba0, client=0x14ce280, msg=0x15100e0) at rpc/virnetserverprogram.c:416
#15 virNetServerProgramDispatch (prog=0x14cfe00, server=0x14c4ba0, client=0x14ce280, msg=0x15100e0) at rpc/virnetserverprogram.c:289
#16 0x00007f956894dff1 in virNetServerHandleJob (jobOpaque=<value optimized out>, opaque=<value optimized out>) at rpc/virnetserver.c:164
#17 0x00007f956889366c in virThreadPoolWorker (opaque=<value optimized out>) at util/threadpool.c:144
#18 0x00007f9568892f89 in virThreadHelper (data=<value optimized out>) at util/threads-pthread.c:161
#19 0x0000003043a077f1 in start_thread () from /lib64/libpthread.so.0
#20 0x00000030436e592d in clone () from /lib64/libc.so.6
Comment 1 Eduardo Habkost 2012-03-07 19:47:32 UTC 
Oops, fixing component.
Comment 2 Jiri Denemark 2012-03-07 21:26:08 UTC 
Let's face it... it was me who messed this up and I'll take care of fixing it :-)
Comment 3 Eric Blake 2012-03-09 16:04:10 UTC 
This bug will also affect live snapshot, followed by stopping the VM, followed by reverting to the snapshot, if the VM had a host cpu passthrough.  Basically, any time we restart a qemu process based on state from a previously running qemu, we have to ensure that we are restarting the new qemu with the same cpu setup.
Comment 4 Jiri Denemark 2012-03-13 07:14:27 UTC 
Fixed upstream by v0.9.10-187-g041109a and sent for internal review: http://post-office.corp.redhat.com/archives/rhvirt-patches/2012-March/msg01174.html
Comment 8 dyuan 2012-03-14 02:43:32 UTC 
Verified PASS with libvirt-0.9.10-5.el6, reproduced with libvirt-0.9.10-4.el6.

# sh -x crash-libvirt.sh 
+ cat
+ virsh define /tmp/crashvm.xml
Domain crashvm defined from /tmp/crashvm.xml

+ virsh start crashvm
Domain crashvm started

+ virsh managedsave crashvm

Domain crashvm state saved by libvirt

+ virsh start crashvm
Domain crashvm started
Comment 10 errata-xmlrpc 2012-06-20 06:49:46 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

http://rhn.redhat.com/errata/RHSA-2012-0748.html
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