lkml.org 
[lkml]   [2017]   [Sep]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [Part1 PATCH v5 02/17] x86/mm: Add Secure Encrypted Virtualization (SEV) support
Hi,

On Thu, Sep 28, 2017 at 01:48:48PM -0500, Brijesh Singh wrote:
> Let me understand the ask, are you saying that we need a method to disable the SEV
> feature from the host OS so that Hypervisor will not be able to create a SEV guest?
> Because once a guest is booted with SEV feature, there is no way to disable the SEV
> feature from the guest.
>
> i.e if "mem_encrypt=smeonly" is set then we clear X86_FEATURE_SEV capability flag
> defined in [1].

So actually we need chicken bits to be able to *enable* both when
CONFIG_AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT is not set.

I.e.,

* mem_encrypt=on - both SME and SEV enabled

* mem_encrypt=smeonly - only SME, no SEV on the host. This option will
basically prevent from using any SEV guests and make the SEV part of the
code inactive. I.e., sev_active() and sev_enabled should be false. As
you say above, we should clear X86_FEATURE_SEV, yes.

* mem_encrypt=off - neither SME/SEV are enabled.

And =on and =off we already have.

How does that sound?

--
Regards/Gruss,
Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
--

\
 
 \ /
  Last update: 2017-09-28 21:24    [W:0.209 / U:0.068 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site