Re: [PATCH 2/7] guest_memfd: Introduce an object to manage the guest-memfd with RamDiscardManager

Peter Xu
2025-01-20T20:46:20Z

On Mon, Jan 20, 2025 at 09:22:50PM +1100, Alexey Kardashevskiy wrote:
> > It is still uncertain how to implement the private MMIO. Our assumption
> > is the private MMIO would also create a memory region with
> > guest_memfd-like backend. Its mr->ram is true and should be managed by
> > RamdDiscardManager which can skip doing DMA_MAP in VFIO's region_add
> > listener.
>
> My current working approach is to leave it as is in QEMU and VFIO.

Agreed. Setting ram=true to even private MMIO sounds hackish, at least
currently QEMU heavily rely on that flag for any possible direct accesses.
E.g., in memory_access_is_direct().

--
Peter Xu