Re: [PATCH -next] memregion: Add arch_flush_memregion() interface

Borislav Petkov
2022-09-08T04:35:15Z

On Wed, Sep 07, 2022 at 09:52:17AM -0700, Dan Williams wrote:
> To be clear nfit stuff and CXL does run in guests, but they do not
> support secure-erase in a guest.
>
> However, the QEMU CXL enabling is building the ability to do *guest
> physical* address space management, but in that case the driver can be
> paravirtualized to realize that it is not managing host-physical address
> space and does not need to flush caches. That will need some indicator
> to differentiate virtual CXL memory expanders from assigned devices.

Sounds to me like that check should be improved later to ask
whether the kernel is managing host-physical address space, maybe
arch_flush_memregion() should check whether the address it is supposed
to flush is host-physical and exit early if not...

--
Regards/Gruss,
Boris.