Re: 4.15.0-rc3 can't create domain when dom0 uses newer kernel

[Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>]

On Mon, Mar 15, 2021 at 04:18:42PM -0400, Tamas K Lengyel wrote:
> Hi all,
> I've ran into a pretty strange issue. I have a freshly installed 4.15.0-rc3
> system and everything works fine with the stock Ubuntu 20.04
> vmlinuz-5.4.0-66-generic as the dom0 kernel - except vmtrace, which needs a
> newer kernel, that's expected. Now if I boot dom0 with
> vmlinuz-5.8.0-44-generic or vmlinuz-5.10.0-1016-oem I can't start any
> domains because of some strange disk error:
> 
> root@t2:/shared/cfg# xl create ubuntu-20.04.cfg
> Parsing config from ubuntu-20.04.cfg
> libxl: error: libxl_device.c:1109:device_backend_callback: Domain 1:unable
> to add device with path /local/domain/0/backend/vbd/1/51712
> libxl: error: libxl_create.c:1613:domcreate_launch_dm: Domain 1:unable to
> add disk devices
> libxl: error: libxl_device.c:1109:device_backend_callback: Domain 1:unable
> to remove device with path /local/domain/0/backend/vbd/1/51712
> libxl: error: libxl_domain.c:1529:devices_destroy_cb: Domain
> 1:libxl__devices_destroy failed
> libxl: error: libxl_domain.c:1182:libxl__destroy_domid: Domain
> 1:Non-existant domain
> libxl: error: libxl_domain.c:1136:domain_destroy_callback: Domain 1:Unable
> to destroy guest
> libxl: error: libxl_domain.c:1063:domain_destroy_cb: Domain 1:Destruction
> of domain failed
> 
> This is the disk config:
> 
> disk = ['phy:/dev/t2vg/ubuntu-20.04,xvda,w']
> 
> It's a standard LVM volume that is active, lvscan shows:
> 
>   ACTIVE            '/dev/t2vg/ubuntu-20.04' [40.00 GiB] inherit
> 
> I checked all the logs and I don't see anything relevant anywhere. If I
> reboot the system with the older kernel everything works as expected as far
> as creating the same domain with the same config.
> 
> Anyone has any idea what might be going on here?

Make sure your kernel has this patch:
https://lore.kernel.org/xen-devel/4c9af052a6e0f6485d1de43f2c38b1461996db99.camel@xxxxxxxxxxxxx/
I'm not sure about the 5.8.x, but for 5.10 it is in >= 5.10.13.

-- 
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab

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