In the context of [1] the 1st patch will be of interest, whereas the
other changes are a result of observations while doing that conversion.

1: convert vendor hook invocations to altcall
2: invoke <vendor>_vpmu_initialise() through a hook as well
3: move vpmu_ops to .init.data

Jan

[1] https://lists.xen.org/archives/html/xen-devel/2021-11/msg01822.html