Re: [for-6.0 v5 00/13] Generalize memory encryption models

From: Cornelia Huck <cohuck@redhat.com>
To: David Gibson <david@gibson.dropbear.id.au>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	pair@us.ibm.com, pbonzini@redhat.com, frankja@linux.ibm.com,
	brijesh.singh@amd.com, qemu-devel@nongnu.org,
	Eduardo Habkost <ehabkost@redhat.com>,
	qemu-ppc@nongnu.org, rth@twiddle.net, thuth@redhat.com,
	berrange@redhat.com, mdroth@linux.vnet.ibm.com,
	Marcelo Tosatti <mtosatti@redhat.com>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Marcel Apfelbaum <marcel.apfelbaum@gmail.com>,
	david@redhat.com,
	Richard Henderson <richard.henderson@linaro.org>,
	kvm@vger.kernel.org, qemu-s390x@nongnu.org, pasic@linux.ibm.com
Subject: Re: [for-6.0 v5 00/13] Generalize memory encryption models
Date: Tue, 8 Dec 2020 13:43:08 +0100	[thread overview]
Message-ID: <20201208134308.2afa0e3e.cohuck@redhat.com> (raw)
In-Reply-To: <20201208025728.GD2555@yekko.fritz.box>

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On Tue, 8 Dec 2020 13:57:28 +1100
David Gibson <david@gibson.dropbear.id.au> wrote:

> On Fri, Dec 04, 2020 at 02:12:29PM +0100, Cornelia Huck wrote:
> > On Fri, 4 Dec 2020 13:07:27 +0000
> > "Dr. David Alan Gilbert" <dgilbert@redhat.com> wrote:
> >   
> > > * Cornelia Huck (cohuck@redhat.com) wrote:  
> > > > On Fri, 4 Dec 2020 09:06:50 +0100
> > > > Christian Borntraeger <borntraeger@de.ibm.com> wrote:
> > > >     
> > > > > On 04.12.20 06:44, David Gibson wrote:    
> > > > > > A number of hardware platforms are implementing mechanisms whereby the
> > > > > > hypervisor does not have unfettered access to guest memory, in order
> > > > > > to mitigate the security impact of a compromised hypervisor.
> > > > > > 
> > > > > > AMD's SEV implements this with in-cpu memory encryption, and Intel has
> > > > > > its own memory encryption mechanism.  POWER has an upcoming mechanism
> > > > > > to accomplish this in a different way, using a new memory protection
> > > > > > level plus a small trusted ultravisor.  s390 also has a protected
> > > > > > execution environment.
> > > > > > 
> > > > > > The current code (committed or draft) for these features has each
> > > > > > platform's version configured entirely differently.  That doesn't seem
> > > > > > ideal for users, or particularly for management layers.
> > > > > > 
> > > > > > AMD SEV introduces a notionally generic machine option
> > > > > > "machine-encryption", but it doesn't actually cover any cases other
> > > > > > than SEV.
> > > > > > 
> > > > > > This series is a proposal to at least partially unify configuration
> > > > > > for these mechanisms, by renaming and generalizing AMD's
> > > > > > "memory-encryption" property.  It is replaced by a
> > > > > > "securable-guest-memory" property pointing to a platform specific      
> > > > > 
> > > > > Can we do "securable-guest" ?
> > > > > s390x also protects registers and integrity. memory is only one piece
> > > > > of the puzzle and what we protect might differ from platform to 
> > > > > platform.
> > > > >     
> > > > 
> > > > I agree. Even technologies that currently only do memory encryption may
> > > > be enhanced with more protections later.    
> > > 
> > > There's already SEV-ES patches onlist for this on the SEV side.
> > > 
> > > <sigh on haggling over the name>
> > > 
> > > Perhaps 'confidential guest' is actually what we need, since the
> > > marketing folks seem to have started labelling this whole idea
> > > 'confidential computing'.  
> 
> That's not a bad idea, much as I usually hate marketing terms.  But it
> does seem to be becoming a general term for this style of thing, and
> it doesn't overlap too badly with other terms ("secure" and
> "protected" are also used for hypervisor-from-guest and
> guest-from-guest protection).
> 
> > It's more like a 'possibly confidential guest', though.  
> 
> Hmm.  What about "Confidential Guest Facility" or "Confidential Guest
> Mechanism"?  The implication being that the facility is there, whether
> or not the guest actually uses it.
> 

"Confidential Guest Enablement"? The others generally sound fine to me
as well, though; not sure if "Facility" might be a bit confusing, as
that term is already a bit overloaded.

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