[PATCH v9 07/13] KVM: guest_memfd: Add flag to remove from direct map

[Edgecombe, Rick P]

On Thu, 2026-01-22 at 14:47 -0800, Ackerley Tng wrote:
> 
> There's no use case I can think of for unmapping TDX private memory
> from the host direct map, but Sean's suggestion
> https://lore.kernel.org/all/aWpcDrGVLrZOqdcg@google.com/ won't even
> let shared guest_memfd memory be unmapped from the direct map for TDX
> VMs.

Ah!

> 
> Actually, does TDX's clflush that assumes presence in the direct map
> apply only for private pages, or all pages?
> 
> If TDX's clflush only happens for private pages, then we could
> restore private pages to the direct map, and then we'd be safe even
> for TDX?

Yes, just private pages need the special treatment. But it will be much
simpler to start with just blocking the option for TDX. A shared pages
only mode could come later.

In general I think we should try to break things up like this when we
can. Kernel code is not set in stone, only ABI. I think it will lead to
overall faster upstreaming, because the series' can be simpler.