[PATCH v2 1/1] KVM: arm64: Allow cacheable stage 2 mapping using VMA flags

[David Hildenbrand]

>> I don't see how VM_PFNMAP alone can tell us anything about the
>> access properties supported by a device address range. Either way,
>> it's the driver setting vm_page_prot or some VM_* flag. KVM has no
>> clue, it's just a memory slot.
> 
> I think David's point about VM_PFNMAP was to avoid some of the
> pfn_valid() logic. If we get VM_PFNMAP we just assume it is non-struct
> page and follow the VMA's pgprot.

Exactly what I meant.

If we only expect DEVICE stuff in VM_PFNMAP, then we can limit all the 
weirdness (and figuring out what todo using pgprot etc) to exactly that.

VM_IO without VM_PFNMAP might be interesting; not sure if we even want 
to support that here.

-- 
Cheers,

David / dhildenb