On Thu, Jun 25, 2020 at 03:47:23PM +1000, David Gibson wrote: > On Wed, Jun 24, 2020 at 09:06:48AM +0200, Cornelia Huck wrote: > > On Mon, 22 Jun 2020 16:27:28 +0200 > > Christian Borntraeger <borntraeger@xxxxxxxxxx> 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. > > > > > > > > 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. > > > > > > > > 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. > > > > > > Let me try to summarize what I understand what you try to achieve: > > > one command line parameter for all platforms that > > > > > > common across all platforms: > > > - disable KSM > > > - by default enables iommu_platform > > > > > > > > > per platform: > > > - setup the necessary encryption scheme when appropriate > > > - block migration > > > -.... > > > > > > > > > The tricky part is certainly the per platform thing. For example on > > > s390 we just have a cpumodel flag that provides interfaces to the guest > > > to switch into protected mode via the ultravisor. This works perfectly > > > fine with the host model, so no need to configure anything. The platform > > > code then disables KSM _on_switchover_ and not in general. Because the > > > guest CAN switch into protected, but it does not have to. > > > > > > So this feels really hard to do right. Would a virtual BoF on KVM forum > > > be too late? We had a BoF on protected guests last year and that was > > > valuable. > > > > Maybe we can do some kind of call to discuss this earlier? (Maybe in > > the KVM call slot on Tuesdays?) I think it would be really helpful if > > everybody would have at least a general understanding about how > > encryption/protection works on the different architectures. > > Yes, I think this would be a good idea. KVM Forum is probably later > than we want, plus since it is virtual, I probably won't be shifting > into the right timezone to attend much of it. > > I don't know when that Tuesday KVM call is. Generally the best > available time for Australia/Europe meetings this time of year is 9am > CET / 5pm AEST. As a once off I could go somewhat later into my > evening, though. Oh.. plus I'm on holiday next week and the one after (27 Jun - 12 Jul). -- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson
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