On Fri, Feb 23, 2018 at 12:32 AM, Larrew, Jesse <Jesse.Larrew@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. [1]: https://github.com/hyperhq/qemu/commit/162b05b38ddb8505c209cf3c570d70c76427c... Cheers, Tao
[1] Secure Encrypted Virtualization API v0.16: https://support.amd.com/TechDocs/55766_SEV-KM%20API_Specification.pdf
Sincerely, Jesse
-----Original Message----- From: Tao Peng [mailto:bergwolf@hyper.sh] Sent: Thursday, February 22, 2018 5:15 AM To: Larrew, Jesse <Jesse.Larrew@amd.com> Cc: kata-dev@lists.katacontainers.io; Hollingsworth, Brent <brent.hollingsworth@amd.com>; Kaplan, David <David.Kaplan@amd.com>; Woller, Thomas <thomas.woller@amd.com> Subject: Re: [kata-dev] Kata with AMD Secure Encrypted Virtualization (SEV)
Hi Larrew,
I’m not familiar with qemu VM clone. Is there any documentation or source files I could browse to learn more?
Sorry I meant to say live migration instead of clone since qemu clone is mostly used to mean guest image cloning. Here is some background I can find online: https://developers.redhat.com/blog/2015/03/24/live-migrating-qemu-kvm- virtual-machines/
Cheers, Tao -- bergwolf@hyper.sh
-- bergwolf@hyper.sh