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[Qemu-devel] [Bug 897750] Re: libvirt/kvm problem with disk attach/detac
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From: |
Justin L Werner |
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Subject: |
[Qemu-devel] [Bug 897750] Re: libvirt/kvm problem with disk attach/detach/reattach on running virt |
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Date: |
Mon, 19 Dec 2011 22:32:50 -0000 |
Some incremental findings:
In 'qemu-kvm' the DeviceState for the peer device of the
BlockDeviceState that gets created when a disk attached by 'virsh
attach-disk' references the 'QemuOpts' options structure that lists the
options and the device ID string (ex: as 'virtio-disk4') that will (on a
re-attach for the same disk when the hotplug module is not loaded in the
virt) be found by 'qemu_find_opts()' under the call to 'drive_add'.
When the PCI hotplug module *is* loaded in the virt, the DriveState structure
and the associatsd QemuOpts get released from within a separate thread by a
call to 'qdev_free()' asynchronously from the main thread's invocation of
'do_device_del()'. When the PCI hotplug modules is *not* loaded in the
virt, there is never an invocation of 'qdev_free' for the device , so the
options structure hangs around to be located in the attempt to re-attach a disk
for the same disk, and we get the Duplicate ID error. In the even of the
hotplug module being loaded in the virt, the trace of the thread which invokes
'qdev_free' looks something like:
==
#1 0x00007fbb4b3403d9 in qdev_free (dev=0x7fbb4cc8d820) at
/home/justinlw/src/qemu/qemu-kvm-0.14.1+noroms/hw/qdev.c:382
#2 0x00007fbb4b4aabd7 in pciej_write (opaque=0x7fbb4c95dc90, addr=44552,
val=33554432)
at /home/justinlw/src/qemu/qemu-kvm-0.14.1+noroms/hw/acpi_piix4.c:615
#3 0x00007fbb4b309839 in ioport_write (index=2, address=44552, data=33554432)
at ioport.c:81
#4 0x00007fbb4b30a2c7 in cpu_outl (addr=44552, val=33554432) at ioport.c:278
#5 0x00007fbb4b2a7b82 in kvm_handle_io (port=44552, data=0x7fbb4b1fa000,
direction=1, size=4, count=1)
at /home/justinlw/src/qemu/qemu-kvm-0.14.1+noroms/kvm-all.c:824
#6 0x00007fbb4b2aa353 in kvm_run (env=0x7fbb4c734860) at
/home/justinlw/src/qemu/qemu-kvm-0.14.1+noroms/qemu-kvm.c:617
#7 0x00007fbb4b2abab8 in kvm_cpu_exec (env=0x7fbb4c734860) at
/home/justinlw/src/qemu/qemu-kvm-0.14.1+noroms/qemu-kvm.c:1233
#8 0x00007fbb4b2ac2dd in kvm_main_loop_cpu (env=0x7fbb4c734860) at
/home/justinlw/src/qemu/qemu-kvm-0.14.1+noroms/qemu-kvm.c:1419
#9 0x00007fbb4b2ac476 in ap_main_loop (_env=0x7fbb4c734860) at
/home/justinlw/src/qemu/qemu-kvm-0.14.1+noroms/qemu-kvm.c:1466
#10 0x00007fbb4a9bbefc in start_thread (arg=0x7fbb4397f700) at
pthread_create.c:304
#11 0x00007fbb481c589d in clone () at
../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#12 0x0000000000000000 in ?? ()
==
In a nutshell, the code is designed such that there is a resource leak
if the virt does not play ball with PCI hotplugging in a case like this.
I have yet to do complete line of code: I will have to have a much
better understanding of the Qemu PCI handling mechanisms first, I think.
Still I believe there are potentially useful findings in further nailing
this bug (design feature?).
--
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https://bugs.launchpad.net/bugs/897750
Title:
libvirt/kvm problem with disk attach/detach/reattach on running virt
Status in QEMU:
New
Status in “qemu-kvm” package in Ubuntu:
Confirmed
Bug description:
Release: Ubuntu 11.10 (Oneiric)
libvirt-bin: 0.9.2-4ubuntu15.1
qemu-kvm: 0.14.1+noroms-0ubuntu6
Summary: With a running KVM virt, performing an 'attach-disk', then a
'detach-disk', then another 'attach-disk'
in an attempt to reattach the volume at the same point on the virt, fails,
with the qemu reporting back to
libvirt a 'Duplicate ID' error.
Expected behavior: The 2nd invocation of 'attach-disk' should have succeeded
Actual behavior: Duplicate ID error reported
I believe this is most likely a qemu-kvm issue, as the DOM kvm spits back at
libvirt after the 'detach-disk'
does not show the just-detached disk. There is some kind of registry/lookup
for devices in qemu-kvm
and for whatever reason, the entry for the disk does not get removed when it
is detached from the
virt. Specifically, the error gets reported at the 2nd attach-disk attempt
from:
qemu-option.c:qemu_opts_create:697
684 QemuOpts *qemu_opts_create(QemuOptsList *list, const char *id, int
fail_if_exists)
685 {
686 QemuOpts *opts = NULL;
687
688 if (id) {
689 if (!id_wellformed(id)) {
690 qerror_report(QERR_INVALID_PARAMETER_VALUE, "id", "an
identifier");
691 error_printf_unless_qmp("Identifiers consist of letters,
digits, '-', '.', '_', starting with a letter.\n");
692 return NULL;
693 }
694 opts = qemu_opts_find(list, id);
695 if (opts != NULL) {
696 if (fail_if_exists) {
697 qerror_report(QERR_DUPLICATE_ID, id, list->name);
<<<< ====== HERE ===========
698 return NULL;
699 } else {
700 return opts;
701 }
702 }
703 }
704 opts = qemu_mallocz(sizeof(*opts));
705 if (id) {
706 opts->id = qemu_strdup(id);
707 }
708 opts->list = list;
709 loc_save(&opts->loc);
710 QTAILQ_INIT(&opts->head);
711 QTAILQ_INSERT_TAIL(&list->head, opts, next);
712 return opts;
713 }
========================================
Output of my attach/detach/attach
========================================
virsh # attach-disk base1 /var/lib/libvirt/images/extrastorage.img vdb
Disk attached successfully
virsh # dumpxml base1
<domain type='kvm' id='2'>
<name>base1</name>
<uuid>9ebebe7f-7dfa-4735-a80c-c19ebe4e1459</uuid>
<memory>1048576</memory>
<currentMemory>1048576</currentMemory>
<vcpu>2</vcpu>
<os>
<type arch='x86_64' machine='pc-0.14'>hvm</type>
<boot dev='hd'/>
</os>
<features>
<acpi/>
<apic/>
<pae/>
</features>
<cpu match='exact'>
<model>Opteron_G3</model>
<vendor>AMD</vendor>
<feature policy='require' name='skinit'/>
<feature policy='require' name='vme'/>
<feature policy='require' name='mmxext'/>
<feature policy='require' name='fxsr_opt'/>
<feature policy='require' name='cr8legacy'/>
<feature policy='require' name='ht'/>
<feature policy='require' name='3dnowprefetch'/>
<feature policy='require' name='3dnowext'/>
<feature policy='require' name='wdt'/>
<feature policy='require' name='extapic'/>
<feature policy='require' name='pdpe1gb'/>
<feature policy='require' name='osvw'/>
<feature policy='require' name='cmp_legacy'/>
<feature policy='require' name='3dnow'/>
</cpu>
<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='raw'/>
<source file='/dev/rbd1'/>
<target dev='vda' bus='virtio'/>
<alias name='virtio-disk0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x05'
function='0x0'/>
</disk>
<disk type='block' device='disk'>
<driver name='qemu' type='raw'/>
<source dev='/var/lib/libvirt/images/extrastorage.img'/>
<target dev='vdb' bus='virtio'/>
<alias name='virtio-disk1'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x07'
function='0x0'/>
</disk>
<controller type='ide' index='0'>
<alias name='ide0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x01'
function='0x1'/>
</controller>
<interface type='bridge'>
<mac address='52:54:00:a2:c1:2d'/>
<source bridge='br0'/>
<target dev='vnet0'/>
<model type='virtio'/>
<alias name='net0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x03'
function='0x0'/>
</interface>
<serial type='pty'>
<source path='/dev/pts/1'/>
<target port='0'/>
<alias name='serial0'/>
</serial>
<console type='pty' tty='/dev/pts/1'>
<source path='/dev/pts/1'/>
<target type='serial' port='0'/>
<alias name='serial0'/>
</console>
<input type='mouse' bus='ps2'/>
<graphics type='vnc' port='5900' autoport='yes'/>
<sound model='ich6'>
<alias name='sound0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x04'
function='0x0'/>
</sound>
<video>
<model type='cirrus' vram='9216' heads='1'/>
<alias name='video0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x02'
function='0x0'/>
</video>
<memballoon model='virtio'>
<alias name='balloon0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x06'
function='0x0'/>
</memballoon>
</devices>
<seclabel type='dynamic' model='apparmor'>
<label>libvirt-9ebebe7f-7dfa-4735-a80c-c19ebe4e1459</label>
<imagelabel>libvirt-9ebebe7f-7dfa-4735-a80c-c19ebe4e1459</imagelabel>
</seclabel>
</domain>
virsh # detach-disk base1 vdb
Disk detached successfully
virsh # dumpxml base1
<domain type='kvm' id='2'>
<name>base1</name>
<uuid>9ebebe7f-7dfa-4735-a80c-c19ebe4e1459</uuid>
<memory>1048576</memory>
<currentMemory>1048576</currentMemory>
<vcpu>2</vcpu>
<os>
<type arch='x86_64' machine='pc-0.14'>hvm</type>
<boot dev='hd'/>
</os>
<features>
<acpi/>
<apic/>
<pae/>
</features>
<cpu match='exact'>
<model>Opteron_G3</model>
<vendor>AMD</vendor>
<feature policy='require' name='skinit'/>
<feature policy='require' name='vme'/>
<feature policy='require' name='mmxext'/>
<feature policy='require' name='fxsr_opt'/>
<feature policy='require' name='cr8legacy'/>
<feature policy='require' name='ht'/>
<feature policy='require' name='3dnowprefetch'/>
<feature policy='require' name='3dnowext'/>
<feature policy='require' name='wdt'/>
<feature policy='require' name='extapic'/>
<feature policy='require' name='pdpe1gb'/>
<feature policy='require' name='osvw'/>
<feature policy='require' name='cmp_legacy'/>
<feature policy='require' name='3dnow'/>
</cpu>
<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='raw'/>
<source file='/dev/rbd1'/>
<target dev='vda' bus='virtio'/>
<alias name='virtio-disk0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x05'
function='0x0'/>
</disk>
<controller type='ide' index='0'>
<alias name='ide0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x01'
function='0x1'/>
</controller>
<interface type='bridge'>
<mac address='52:54:00:a2:c1:2d'/>
<source bridge='br0'/>
<target dev='vnet0'/>
<model type='virtio'/>
<alias name='net0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x03'
function='0x0'/>
</interface>
<serial type='pty'>
<source path='/dev/pts/1'/>
<target port='0'/>
<alias name='serial0'/>
</serial>
<console type='pty' tty='/dev/pts/1'>
<source path='/dev/pts/1'/>
<target type='serial' port='0'/>
<alias name='serial0'/>
</console>
<input type='mouse' bus='ps2'/>
<graphics type='vnc' port='5900' autoport='yes'/>
<sound model='ich6'>
<alias name='sound0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x04'
function='0x0'/>
</sound>
<video>
<model type='cirrus' vram='9216' heads='1'/>
<alias name='video0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x02'
function='0x0'/>
</video>
<memballoon model='virtio'>
<alias name='balloon0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x06'
function='0x0'/>
</memballoon>
</devices>
<seclabel type='dynamic' model='apparmor'>
<label>libvirt-9ebebe7f-7dfa-4735-a80c-c19ebe4e1459</label>
<imagelabel>libvirt-9ebebe7f-7dfa-4735-a80c-c19ebe4e1459</imagelabel>
</seclabel>
</domain>
virsh # attach-disk base1 /var/lib/libvirt/images/extrastorage.img vdb
error: Failed to attach disk
error: operation failed: adding
virtio-blk-pci,bus=pci.0,addr=0x8,drive=drive-virtio-disk1,id=virtio-disk1
device failed: Duplicate ID 'virtio-disk1' for device
======================================================
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