Re: [PATCH] tdx, memory hotplug: Check whole hot-adding memory range for TDX

[David Hildenbrand <david@redhat.com>]

> Because only TDX compatible memory can be used for TDX guest.  The buddy
> is used to allocate memory for TDX guest.  While devdax will not be used
> for that.
> 
>>> This also makes the original TDX memory hotplug notifier useless, so
>>> delete it.
>>
>> The online-notifier would even be too late when used with the
>> memmap-on-memory feature I assume, as we might be touching that memory
>> even before being able to call memory online notifiers.
> 
> This should be OK.  Because we will not use the memory for TDX guest in
> this way.

Thanks for the reminder, I keep assuming that we are hotplugging memory 
into the guest, not the hypervisor.

Having that as a comment in tdx_check_hotplug_memory_range() would be 
helpful: we don't allow mixture of TDX and !TDX memory in the buddy so 
we won't run into trouble when launching encrypted VMs that really need 
TDX-capable memory.

-- 
Cheers,

David / dhildenb