Re: [PATCH v3 5/5] x86/sev-es: Do not support MMIO to/from encrypted memory

[Borislav Petkov]

On Wed, Oct 21, 2020 at 02:39:38PM +0200, Joerg Roedel wrote:
> From: Joerg Roedel <jroedel@xxxxxxx>
> 
> MMIO memory is usually not mapped encrypted, so there is no reason to
> support emulated MMIO when it is mapped encrypted.
> 
> This prevents a possible hypervisor attack where it maps a RAM page as

"Prevent... "

> an MMIO page in the nested page-table, so that any guest access to it
> will trigger a #VC exception and leak the data on that page to the
						^

"... via the GHCB (like with normal MMIO)... "

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette