Re: [edk2-devel] [PATCH v2] OvmfPkg: Don't make APIC MMIO accesses with encryption bit set

["Ard Biesheuvel" <ardb@kernel.org>]

On Fri, 26 Apr 2024 at 16:16, Roth, Michael via groups.io
<Michael.Roth=amd.com@groups.io> wrote:
>
> On Fri, Apr 26, 2024 at 08:51:20AM -0500, Roth, Michael via groups.io wrote:
> > For the most part, OVMF will clear the encryption bit for MMIO regions,
> > but there is currently one known exception during SEC when the APIC
> > base address is accessed via MMIO with the encryption bit set for
> > SEV-ES/SEV-SNP guests. In the case of SEV-SNP, this requires special
> > handling on the hypervisor side which may not be available in the
> > future[1], so make the necessary changes in the SEC-configured page
> > table to clear the encryption bit for 4K region containing the APIC
> > base address.
> >
> > Since CpuPageTableLib is used to handle the splitting, some additional
> > care must be taken to clear the C-bit in all non-leaf PTEs since the
> > library expects that to be the case. Add handling for that when setting
> > up the SEC page table.
>
> Tom just noticed another spot where a non-leaf C-bit needs to be cleared
> (the one mapping the GHCB page). It doesn't affect patch functionality
> but should be included for completeness of this change, so will send a
> quick v3 with this addressed.
>
> -Mike
>

While at it, could you please fix your email setup and use 8bit
transfer encoding instead of quoted printable? Also, please put me on
cc so I don't have to apply the garbled groups.io copy.


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