Bug#1120807: virt-install: fails to create ppc64el machines due to page size choice

[Helmut Grohne <helmut@subdivi.de>]

Package: virt-install
Version: 1:5.0.0-5+deb13u1
X-Debbugs-Cc: debian-powerpc@lists.debian.org, mjt@debian.org
User: debian-powerpc@lists.debian.org
Usertags: ppc64el

Hello,

I tried using virt-install to create a ppc64el kvm virtual machine. This 
fails with an error relayed from qemu:

| Can't support 64 kiB guest pages with 4 kiB host pages with this KVM implementation

The default machine used by virt-install for ppc64el is "pseries" and it 
appears to default to 64 kiB guest pages. Debian has changed (#1074217) 
the kernel's page size to 4 kiB for trixie though, so that's what Debian 
hosts typically use.

On the qemu side, we may change this by passing:

    -machine pseries,cap-hpt-max-page-size=4096

Now getting this option through virt-install is not obvious. Trying to 
pass a machine with an option to virt-install's --machine option results 
in a failure as it interprets the combination of machine and option as 
the machine and has no clue about this machine.

A workaround here is passing it as a --qemu-commandline.

    --machine=pseries "--qemu-commandline=-machine pseries,cap-hpt-max-page-size=4096"

Would it be possible for virt-install to support this use case in a more 
convenient way? For instance, it could detect the host's page size and 
adjust it itself or it could enable passing such options via --machine.

Thanks for considering

Helmut