Re: [PATCH v5 16/16] x86/tdx: Add cmdline option to force use of ioremap_host_shared

Michael S. Tsirkin
2021-10-11T18:29:06Z

On Mon, Oct 11, 2021 at 10:35:18AM -0700, Andi Kleen wrote:
>
> > Presumably bios code is in arch/x86 and drivers/acpi, right?
> > Up to 200 calls the majority of which is likely private ...
>
> Yes.
>
> > I don't have better ideas but the current setup will just
> > result in people making their guests vulnerable whenever they
> > want to allow device pass-through.
>
>
> Yes that's true. For current TDX our target is virtual devices only. But if
> pass through usage will be really wide spread we may need to revisit.
>
>
> -Andi

I mean ... it's already wide spread. If we support it with TDX
it will be used with TDX. If we don't then I guess it won't,
exposing this kind of limitation in a userspace visible way isn't great
though. I guess it boils down to the fact that
ioremap_host_shared is just not a great interface, users simply
have no idea whether a given driver uses ioremap.

--
MST