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[Qemu-devel] [Bug 897750] Re: libvirt/kvm problem with disk attach/detac


From: Justin L Werner
Subject: [Qemu-devel] [Bug 897750] Re: libvirt/kvm problem with disk attach/detach/reattach on running virt
Date: Wed, 14 Dec 2011 17:10:42 -0000

I've been looking at libvirt and qemu for other work, I'm doing, and
I've criceld back to take another look at this.

Since I first looked at this, my testbed has updated to use the 
"oneiric-proposed"  
   qemu-kvm package '0.14.1+noroms-0ubuntu6.1'
while retaining the libvirt-bin package
   0.9.2-4ubuntu15.1

I tried to duplicate the problem again, but this time my  Linux virt had 
'acpiphp.ko'
(the PCI hotplug module) loaded, and I was *unable* to reproduce the 'Duplicate 
ID'
error.  Instead, continued attach/detach cycles resulted in success every time 
after
.gt. 30 iterations.

==
**As a side-note  and possibly to be addressed as a separate bug, the drive 
does not
actually get attached as the specified device each time inside the virt.   So 
even though
the 'attach-disk --target' specifies, say, vdb,  the virt kernel increments the 
devname
inside itself, so that we get  vdc,  vdd, vde....  The attaches subsequent to 
the detatch
of vdz results in vdaa,, vdab, vdac and so on.
==

Now here's the kicker.  If you do an 'rmmod' on the PCI hotplug module within 
the
virt and try the attach/detach/attach, the 'Duplicate ID' problem re-occurs.   
This
implies to me that there is some sort of effective interaction between qemu-kvm
and the virt that affects this.   That is, when the virt actually gets and 
handles a
device eject, then qemu-kvm behaves differently than when  the virt does not
get/handle it.
--
Dec 14 09:54:16 base1 kernel: [ 2226.835417] acpiphp_glue: 
handle_hotplug_event_func: Device eject notify on \_SB_.PCI0.S27_
Dec 14 09:54:16 base1 kernel: [ 2226.877208] virtio-pci 0000:00:1b.0: PCI INT A 
disabled
--

So, this gives us a better characterization of the bug, and I will look into it 
some more with this
in mind.

-- 
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
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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