(In reply to Meina Li from comment #0)
> Description of problem:
> Guest crash after restart libvirtd when start guest with iscsi-direct volume
> 
> Version-Release number of selected component (if applicable):
> libvirt-4.10.0-1.module+el8+2317+367e35b5.x86_64
> qemu-kvm-3.0.0-2.module+el8+2246+78080371.x86_64
> 
> How reproducible:
> 100%
> 
> Steps to Reproduce:
> 
> 1. Prepare an iscsi-direct pool.
> # virsh pool-dumpxml iscsi-direct 
> <pool type='iscsi-direct'>
>   <name>iscsi-direct</name>
>   <uuid>0799697a-94dd-4115-9601-8714b1931248</uuid>
>   <capacity unit='bytes'>524287488</capacity>
>   <allocation unit='bytes'>524287488</allocation>
>   <available unit='bytes'>0</available>
>   <source>
>     <host name='10.66.144.87'/>
>     <device path='iqn.2017-12.com.virttest:emulated-iscsi-noauth.target2'/>
>     <initiator>
>       <iqn name='iqn.2017-12.com.example:client'/>
>     </initiator>
>   </source>
> </pool>
> 
> # virsh vol-list iscsi-direct 
>  Name         Path                                                          
> 
> -----------------------------------------------------------------------------
> --
>  unit:0:0:0  
> ip-10.66.144.87:3260-iscsi-iqn.2017-12.com.virttest:emulated-iscsi-noauth.
> target2-lun-0
> 
> 2. Start guest with iscsi volume.
> # virsh dumpxml q35 | grep disk -a8
> ...
> <disk type='volume' device='disk'>
>       <driver name='qemu' type='raw'/>
>       <source pool='iscsi-direct' volume='unit:0:0:0' mode='direct'/>
>       <target dev='vdb' bus='virtio'/>
>       <address type='pci' domain='0x0000' bus='0x00' slot='0x07'
> function='0x0'/>
>     </disk>
> 
> # virsh start q35
> Domain q35 started

This is where I have troubles. When I try to start such domain I get the error immediatelly:
virsh # start fedora
error: Failed to start domain fedora
error: XML error: disk source mode is only valid when storage pool is of iscsi type

Is it possible that the domain was started with an older libvirt and what we see here is just during libvirt upgrade?

(In reply to Michal Privoznik from comment #2)
...
> 
> This is where I have troubles. When I try to start such domain I get the
> error immediatelly:
> virsh # start fedora
> error: Failed to start domain fedora
> error: XML error: disk source mode is only valid when storage pool is of
> iscsi type
> 
> Is it possible that the domain was started with an older libvirt and what we
> see here is just during libvirt upgrade?

I can also encounter this trouble in the latest version.
But the domain will start successfully when there's no mode='direct' in domain xml:
# virsh dumpxml q35 | grep disk -a8
...
<disk type='volume' device='disk'>
      <driver name='qemu' type='raw'/>
      <source pool='iscsi-direct' volume='unit:0:0:0'/>              --no mode='direct' in disk source
      <target dev='vdb' bus='virtio'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x0'/>
    </disk>
# virsh start q35
Domain q35 started

I think this maybe an another new bug except there's some new design methods on it. Please review it again, thanks.

Test Version:
libvirt-5.0.0-4.module+el8+2835+faae67de.x86_64
qemu-kvm-3.1.0-18.module+el8+2834+fa8bb6e2.x86_64

Patch proposed upstream:

https://www.redhat.com/archives/libvir-list/2019-March/msg00093.html

I've just merged the commit upstream:

commit e89694735011fad95bf9fc61221744e69d695137
Author:     Michal Privoznik <mprivozn>
AuthorDate: Fri Mar 1 16:05:16 2019 +0100
Commit:     Michal Privoznik <mprivozn>
CommitDate: Mon Mar 4 16:54:11 2019 +0100

    virDomainDiskTranslateSourcePool: Don't set @mode of iscsi-direct
    
    https://bugzilla.redhat.com/show_bug.cgi?id=1658504
    
    This function is called when a domain is starting up (in qemu
    driver that is when qemu cmd line is generated). It is used to
    translate <disk type='volume'/> to something usable by filling in
    virStorageSource (e.g. fetching disk path, or some connection URI
    for a network FS). But some of these info are not stored in
    status XML and thus the function is called on
    qemuProcessReconnect too to reconstruct runtime data. But this
    poses a problem because after the first run the mode is set to
    'direct', but in the second run this triggers a failure because
    mode is valid only for 'iscsi' volumes and not 'iscsi-direct'
    ones.
    
    Signed-off-by: Michal Privoznik <mprivozn>
    Reviewed-by: Erik Skultety <eskultet>


v5.1.0-20-ge896947350

Verified Version:
libvirt-5.4.0-1.module+el8.1.0+3304+7eb41d5f.x86_64
qemu-kvm-4.0.0-4.module+el8.1.0+3356+cda7f1ee.x86_64
kernel-4.18.0-107.el8.x86_64

Verified Steps:
Scenario 1: Start the guest with iscsi-direct volume and check list after libvirtd restart.
1. Prepare an iscsi-direct pool.
# virsh pool-dumpxml iscsi-direct 
<pool type='iscsi-direct'>
  <name>iscsi-direct</name>
  <uuid>2b621385-f734-4b98-8131-0fc17ed29e67</uuid>
  <capacity unit='bytes'>64424704512</capacity>
  <allocation unit='bytes'>64424704512</allocation>
  <available unit='bytes'>0</available>
  <source>
    <host name='**IP**'/>
    <device path='iqn.2017-12.com.virttest:emulated-iscsi-noauth.target2'/>
    <initiator>
      <iqn name='iqn.2017-12.com.example:client'/>
    </initiator>
  </source>
</pool>
# virsh vol-list  iscsi-direct 
 Name         Path
------------------------------------------------------------------------------------------------------
 unit:0:0:0   ip-10.66.4.109:3260-iscsi-iqn.2017-12.com.virttest:emulated-iscsi-noauth.target2-lun-0

2. Start the guest with the following volume disk.
...
<disk type='volume' device='disk'>
      <driver name='qemu' type='raw'/>
      <source pool='iscsi-direct' volume='unit:0:0:0'/>
      <target dev='vdb' bus='virtio'/>
      <address type='pci' domain='0x0000' bus='0x07' slot='0x00' function='0x0'/>
    </disk>
...
# virsh start lmn
Domain lmn started

3. Check the guest info after restart libvirtd/save/restore guest.
# virsh list --all
 Id   Name   State
-----------------------
 1    lmn    running
# systemctl restart libvirtd
# virsh list --all
 Id   Name   State
-----------------------
 5    lmn    running
# virsh save lmn test.save
Domain lmn saved to test.save
# virsh list --all
 Id   Name   State
-----------------------
 -    lmn    shut off
# virsh restore test.save 
Domain restored from test.save
# virsh list --all
 Id   Name   State
-----------------------
 6    lmn    running

Scenario 2: Hotplug/unplug iscsi-pool volume disk to the guest.
1. Prepare the disk xml with iscsi-pool volume info.
# cat disk.xml 
<disk type='volume' device='disk'>
      <driver name='qemu' type='raw'/>
      <source pool='iscsi-direct' volume='unit:0:0:0'/>
      <target dev='vdb' bus='virtio'/>
      <alias name='virtio-disk1'/>
      <address type='pci' domain='0x0000' bus='0x07' slot='0x00' function='0x0'/>
    </disk>

2. Hotplug the disk to guest.
# virsh attach-device lmn disk.xml 
Device attached successfully
# virsh dumpxml lmn | grep disk -a8
...
 <disk type='volume' device='disk'>
      <driver name='qemu' type='raw'/>
      <source pool='iscsi-direct' volume='unit:0:0:0'/>
      <target dev='vdb' bus='virtio'/>
      <alias name='virtio-disk1'/>
      <address type='pci' domain='0x0000' bus='0x07' slot='0x00' function='0x0'/>
    </disk>
...

3. Detach the disk from the guest.
# virsh detach-device lmn disk.xml 
Device detached successfully
# virsh dumpxml lmn | grep disk -a8
...
No this volume disk
...

So move this bug to be verified.

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.

https://access.redhat.com/errata/RHBA-2019:3723