Re: [PATCH v5 2/3] system/memory: Use qemu_ram_move() for directly accessible regions

On Thu, 30 Jul 2026 at 11:27, Michael S. Tsirkin <[email protected]> wrote:
>
> On Thu, Jul 30, 2026 at 10:24:32AM +0100, Peter Maydell wrote:
> > The idea is rather just to ignore the unaligned-access-to-not-RAM
> > case as "only a theoretical issue" and default it to memmove().
> > If anybody reports an actual problem we can think about it then :-)

> Well given the only reported case of virtio DMA into vfio memory we have is
> GH100 and that one is mapped MT_NORMAL, I'm fine with that.

> I feel extending vfio to report the mapping type to userspace might
> not be a bad idea down the road, though. "Directly accessible"
> is a very rough approximation to the rich variety of mappings
> available across architectures.

Yes, this sounds like a good longer term idea. If userspace doesn't
have a way to know what the mapping behind something it's mmap()ed
is then it can't know what operations it can and can't safely do.

-- PMM