Re: [RFC Patch 0/2] KVM: SVM: Cgroup support for SVM SEV ASIDs

[Sean Christopherson]

On Mon, Sep 21, 2020 at 05:40:22PM -0700, Vipin Sharma wrote:
> Hello,
> 
> This patch series adds a new SEV controller for tracking and limiting
> the usage of SEV ASIDs on the AMD SVM platform.
> 
> SEV ASIDs are used in creating encrypted VM and lightweight sandboxes
> but this resource is in very limited quantity on a host.
> 
> This limited quantity creates issues like SEV ASID starvation and
> unoptimized scheduling in the cloud infrastructure.
> 
> SEV controller provides SEV ASID tracking and resource control
> mechanisms.

This should be genericized to not be SEV specific.  TDX has a similar
scarcity issue in the form of key IDs, which IIUC are analogous to SEV ASIDs
(gave myself a quick crash course on SEV ASIDs).  Functionally, I doubt it
would change anything, I think it'd just be a bunch of renaming.  The hardest
part would probably be figuring out a name :-).

Another idea would be to go even more generic and implement a KVM cgroup
that accounts the number of VMs of a particular type, e.g. legacy, SEV,
SEV-ES?, and TDX.  That has potential future problems though as it falls
apart if hardware every supports 1:MANY VMs:KEYS, or if there is a need to
account keys outside of KVM, e.g. if MKTME for non-KVM cases ever sees the
light of day.