Open Stack

On Fri, Feb 23, 2018 at 1:09 PM, Larrew, Jesse <Jesse.Larrew at amd.com> wrote:

> *From:* Ricardo Aravena [mailto:raravena80 at gmail.com]
> *Sent:* Friday, February 23, 2018 10:32 AM
> *To:* Tao Peng <bergwolf at hyper.sh>
> *Cc:* Larrew, Jesse <Jesse.Larrew at amd.com>; Hollingsworth, Brent <
> brent.hollingsworth at amd.com>; Woller, Thomas <thomas.woller at amd.com>;
> Kaplan, David <David.Kaplan at amd.com>; kata-dev at lists.katacontainers.io
> *Subject:* Re: [kata-dev] Kata with AMD Secure Encrypted Virtualization
> (SEV)
>
>
>
>
>
>
>
> On Fri, Feb 23, 2018 at 5:55 AM, Tao Peng <bergwolf at hyper.sh> wrote:
>
> On Fri, Feb 23, 2018 at 12:32 AM, Larrew, Jesse <Jesse.Larrew at amd.com>
> wrote:
> > Ah! Yes, live migration of encrypted guests is supported by the
> hardware. Qemu support is still being actively developed though. The
> details of migrating encrypted VMs are discussed in our Secure Encrypted
> Virtualization API [1]. Basically, the AMD Secure Processor re-encrypts and
> integrity-protects the guest memory into discrete "packets" that can be
> sent to the destination machine. The transport/integrity keys used for
> migration are ephemeral keys negotiated with the receiving machine using a
> Diffie-Hellman exchange.
> >
> > Live migration is useful for VMs that need to be stateful. However, my
> impression of container use cases is that they are encouraged to be
> stateless. For stateless containers, it would most likely be quicker to
> simply throw away the container and start a new one on the destination
> machine. Do you have specific use cases that require the ability to migrate
> containers?
> >
> Yes. We have an optimization [1] based on the qemu live migration
> feature which let us share the initial part of guest memory among
> guests on the same host. It's a quite useful feature for vm-based
> container workload because the kernel and initramfs are most likely
> the same for all guests on the host.
>
>
>
> My two cents here:
>
>
>
> It's also quite useful at a higher level when you are dealing with
> stateful services, that are not heavily containerized in prod yet. First
> ones that pop in my head are redis/memchached. Then there's also big data
> stateful type of dbs that require a lot memory, say Cassandra, or Scylla.
>
>
>
> That’s good information. Thanks! I’m definitely trying to understand which
> workloads would benefit most from the container-in-a-VM approach, and which
> features/capabilities are most important.
>
>
>
> Are there any other features/tricks that an SEV implementation would need
> to preserve?
>


You're welcome!

How about live migration recovery for disaster recovery (DR) type of
scenarios? If for some reason somebody or something pulls the plug on
either the server migrating from or the server migrating to, in the middle
of it all. It would be nice if the data wouldn't get corrupted.

There's a data protection section in the API spec, not sure if that covers
that.  Also from the sounds of it, it looks like the the platform key would
be different for each server.

Overall SEV looks great IMO.

Cheers,
Ricardo




>
>
> Sincerely,
>
> Jesse
>
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