amd64 efirt: initialize vm_pages backing EFI runtime memory

[kib]

Summary

so that PHYS_TO_VM_PAGE() and consequently physcopyin() work for them

[markj]

sys/amd64/amd64/efirt_machdep.c

252

p->md_phys + ptoa(idx) can be written as va, or is it intentional? I guess PHYS_TO_VM_PAGE(va) looks a bit suspicious.

258

I don't understand the purpose of introducing vm_page_init_page_partial() if you're going to manually override these fields anyway.

[kib]

I considered initializing m->phys_addr for all pages in vm_page_array[]. I decided to not do it for this change because I set up other attributes, the mode is most important. But I think it is useful to have VM_PAGE_TO_PHYS/PHYS_TO_VM_PAGE to work somehow for low addresses.

sys/amd64/amd64/efirt_machdep.c

258

I tried to avoid initializing the same field twice. Well, except the md_mode.

[kib]

Use vm_page_init_page().
Re-use va.