From: Cornelia Huck <cohuck@redhat.com>
To: David Hildenbrand <david@redhat.com>
Cc: David Gibson <david@gibson.dropbear.id.au>,
qemu-devel@nongnu.org, brijesh.singh@amd.com, pair@us.ibm.com,
pbonzini@redhat.com, dgilbert@redhat.com, frankja@linux.ibm.com,
Marcel Apfelbaum <marcel.apfelbaum@gmail.com>,
kvm@vger.kernel.org, qemu-ppc@nongnu.org, mst@redhat.com,
mdroth@linux.vnet.ibm.com, Richard Henderson <rth@twiddle.net>,
pasic@linux.ibm.com, Eduardo Habkost <ehabkost@redhat.com>,
qemu-s390x@nongnu.org
Subject: Re: [PATCH v3 0/9] Generalize memory encryption models
Date: Fri, 19 Jun 2020 11:45:26 +0200 [thread overview]
Message-ID: <20200619114526.6a6f70c6.cohuck@redhat.com> (raw)
In-Reply-To: <e045e202-cd56-4ddc-8c1d-a2fe5a799d32@redhat.com>
On Fri, 19 Jun 2020 10:28:22 +0200
David Hildenbrand <david@redhat.com> wrote:
> On 19.06.20 04:05, 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.
>
> Each architecture finds its own way to vandalize the original
> architecture, some in more extreme/obscure ways than others. I guess in
> the long term we'll regret most of that, but what do I know :)
>
> >
> > 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
> > "host-trust-limitation" property pointing to a platform specific
> > object which configures and manages the specific details.
> >
>
> I consider the property name sub-optimal. Yes, I am aware that there are
> other approaches being discussed on the KVM list to disallow access to
> guest memory without memory encryption. (most of them sound like people
> are trying to convert KVM into XEN, but again, what do I know ... :) )
>
> "host-trust-limitation" sounds like "I am the hypervisor, I configure
> limited trust into myself". Also, "untrusted-host" would be a little bit
> nicer (I think trust is a black/white thing).
>
> However, once we have multiple options to protect a guest (memory
> encryption, unmapping guest pages ,...) the name will no longer really
> suffice to configure QEMU, no?
Hm... we could have a property that accepts bits indicating where the
actual limitation lies. Different parts of the code could then make
more fine-grained decisions of what needs to be done. Feels a bit
overengineered today; but maybe there's already stuff with different
semantics in the pipeline somewhere?
>
> > For now this series covers just AMD SEV and POWER PEF. I'm hoping it
> > can be extended to cover the Intel and s390 mechanisms as well,
> > though.
>
> The only approach on s390x to not glue command line properties to the
> cpu model would be to remove the CPU model feature and replace it by the
> command line parameter. But that would, of course, be an incompatible break.
Yuck.
We still need to provide the cpu feature to the *guest* in any case, no?
>
> How do upper layers actually figure out if memory encryption etc is
> available? on s390x, it's simply via the expanded host CPU model.
>
next prev parent reply other threads:[~2020-06-19 9:45 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-19 2:05 [PATCH v3 0/9] Generalize memory encryption models David Gibson
2020-06-19 2:05 ` [PATCH v3 1/9] host trust limitation: Introduce new host trust limitation interface David Gibson
2020-06-26 11:01 ` Dr. David Alan Gilbert
2020-07-14 19:26 ` Richard Henderson
2020-06-19 2:05 ` [PATCH v3 2/9] host trust limitation: Handle memory encryption via interface David Gibson
2020-06-19 2:05 ` [PATCH v3 3/9] host trust limitation: Move side effect out of machine_set_memory_encryption() David Gibson
2020-06-19 2:05 ` [PATCH v3 4/9] host trust limitation: Rework the "memory-encryption" property David Gibson
2020-07-14 19:36 ` Richard Henderson
2020-06-19 2:05 ` [PATCH v3 5/9] host trust limitation: Decouple kvm_memcrypt_*() helpers from KVM David Gibson
2020-06-19 2:05 ` [PATCH v3 6/9] host trust limitation: Add Error ** to HostTrustLimitation::kvm_init David Gibson
2020-06-19 2:06 ` [PATCH v3 7/9] spapr: Add PEF based host trust limitation David Gibson
2020-06-19 2:06 ` [PATCH v3 8/9] spapr: PEF: block migration David Gibson
2020-06-26 10:33 ` Dr. David Alan Gilbert
2020-07-05 7:38 ` David Gibson
2020-06-19 2:06 ` [PATCH v3 9/9] host trust limitation: Alter virtio default properties for protected guests David Gibson
2020-06-19 10:12 ` Daniel P. Berrangé
2020-06-19 11:46 ` Michael S. Tsirkin
2020-06-19 11:47 ` Michael S. Tsirkin
2020-06-19 12:16 ` Daniel P. Berrangé
2020-06-19 20:04 ` Halil Pasic
2020-06-24 7:55 ` Michael S. Tsirkin
2020-06-25 4:57 ` David Gibson
2020-06-25 5:02 ` David Gibson
2020-06-19 14:45 ` David Gibson
2020-06-19 15:05 ` Daniel P. Berrangé
2020-06-20 8:24 ` David Gibson
2020-06-22 9:09 ` Daniel P. Berrangé
2020-06-25 5:06 ` David Gibson
2020-06-19 2:42 ` [PATCH v3 0/9] Generalize memory encryption models no-reply
2020-06-19 8:28 ` David Hildenbrand
2020-06-19 9:45 ` Cornelia Huck [this message]
2020-06-19 9:56 ` David Hildenbrand
2020-06-19 10:05 ` Cornelia Huck
2020-06-19 10:10 ` David Hildenbrand
2020-06-22 12:02 ` Cornelia Huck
2020-06-25 5:25 ` David Gibson
2020-06-25 7:06 ` David Hildenbrand
2020-06-26 4:42 ` David Gibson
2020-06-26 6:53 ` David Hildenbrand
2020-06-26 9:01 ` Janosch Frank
2020-06-26 9:32 ` Daniel P. Berrangé
2020-06-26 9:49 ` Janosch Frank
2020-06-26 10:29 ` Dr. David Alan Gilbert
2020-06-26 10:58 ` Daniel P. Berrangé
2020-06-26 12:49 ` Janosch Frank
2020-07-01 11:59 ` Halil Pasic
2020-06-19 9:48 ` David Gibson
2020-06-19 10:04 ` David Hildenbrand
2020-06-25 5:42 ` David Gibson
2020-06-25 6:59 ` David Hildenbrand
2020-06-25 9:49 ` Cornelia Huck
2020-06-22 14:27 ` Christian Borntraeger
2020-06-24 7:06 ` Cornelia Huck
2020-06-25 5:47 ` David Gibson
2020-06-25 5:48 ` David Gibson
2020-06-25 5:44 ` David Gibson
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