Re: [RFC PATCH] x86/xen: Consider Xen PVH support in CONFIG_XEN_PVHVM

Jan Beulich
2026-02-24T11:01:32Z

On 24.02.2026 11:51, Teddy Astie wrote:
> It's currently possible to build Linux with CONFIG_PVH|CONFIG_XEN_PVHVM
> and no CONFIG_XEN_PVH.

In which case, how can you expect Xen PVH to work?

> That leads to inconsistent kernels that fails with
> "Missing xen PVH initialization" when booting using PVH boot method or
> display various errors and fail to initialize Xen PV drivers when booting
> with PVH-GRUB.
>
> platform_pci_unplug: Xen Platform PCI: unrecognised magic value
> ...
> # modprobe xen-blkfront
> modprobe: ERROR: could not insert 'xen_blkfront': No such device
> # modprobe xen-netfront
> modprobe: ERROR: could not insert 'xen_netfront': No such device
>
> When built without CONFIG_XEN_PVH, PVH-specific logic is disabled, hence when
> booting with e.g PVH-OVMF, Linux assumes we are a HVM guest, even when we aren't
> actually one (in the "with HVM emulated devices" sense).
>
> As it is actually possible to boot Xen PVH without CONFIG_PVH; and that most
> Xen-related logic exist within CONFIG_XEN_PVHVM; consider PVH guests support
> within CONFIG_XEN_PVHVM instead of CONFIG_XEN_PVH.

XEN_PVHVM serves a different purpose though, iirc.

Jan