This should live in pmap.c, and be marked as __read_mostly, e.g. like pmap_sh_attr. It would be useful to have pa in the name to make it obvious it's to be applied to the physical address. If FEAT_LPA2 is enabled it may not work with a page table as bits 51:50 of the output address are in bits 9:8 of the page table.

To get all physical memory we will need a new function that doesn't exclude EXFLAG_NOALLOC memory (e.g. the kernel image). Something like the following:

size_t
physmem_all(vm_paddr_t *avail, size_t maxavail) 
{
        return (regions_to_avail(avail, 0, maxavail, 0, NULL, NULL));
}

physmem_avail builds the array of physical memory we can allocate from so will not be complete.

We could drop these printf calls, or put them behind bootverbose