[Linaro-open-discussions] Re: [Question - ARM CCA] Regarding vCPU Hotplug Support in ARM Realm world

Hi Salil,

On 7/17/23 18:17, Salil Mehta wrote:

I recently got a chance to look into the ARM CCA specifications. And if I understood correctly then in Realm world PSCI is managed by RMM but the Realm vCPUs are taken care by the host. As per our recent changes we handle the SMC/HVC hyper call exits in user-space. If the VMs are to run in Realm world and vCPU Hotplug needs to be supported then do we need to consider any change there?

It would need a call between EL2 and R-EL2 to set which CPUs the realm is allowed to bring online via PSCI. I don't think would be too much of a problem.

We didn't do that for the kernel because it was better to avoid creating more in-kernel state that has to be migrated.

Thanks,

James