Re: [PATCH 1/2] x86/pat: fix x86_has_pat_wp()

From: Juergen Gross
Date: Mon Jun 20 2022 - 11:34:49 EST


On 20.06.22 17:27, Dave Hansen wrote:
On 6/20/22 03:41, Juergen Gross wrote:
But I'm only guessing - this needs a *lot* more elaboration and
explanation why exactly this is needed.

I will correct the code and update the commit message.

It would also be great to cover the end-user-visible impact of the bug
and the fix. It _looks_ like it will probably only affect an SEV
system's ability to read some EFI data. That will presumably be pretty
bad because it ends up reading from an encrypted mapping instead of a
decrypted one.

Xen doesn't support SEV guests yet. So the only caveat here would be EFI
setting up PAT by itself.

Not sure this is really a real world issue.


Juergen

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