On Wed, 19 Jan 2022 06:42:15 +0000, Jason Wang <jasowang@xxxxxxxxxx> wrote: > > > 在 2022/1/5 上午3:49, Raghavendra Rao Ananta 写道: > > KVM regularly introduces new hypercall services to the guests without > > any consent from the Virtual Machine Manager (VMM). This means, the > > guests can observe hypercall services in and out as they migrate > > across various host kernel versions. This could be a major problem > > if the guest discovered a hypercall, started using it, and after > > getting migrated to an older kernel realizes that it's no longer > > available. Depending on how the guest handles the change, there's > > a potential chance that the guest would just panic. > > > > As a result, there's a need for the VMM to elect the services that > > it wishes the guest to discover. VMM can elect these services based > > on the kernels spread across its (migration) fleet. To remedy this, > > extend the existing firmware psuedo-registers, such as > > KVM_REG_ARM_PSCI_VERSION, for all the hypercall services available. > > > > Haven't gone through the series but I wonder whether it's better to > have a (e)BPF filter for this like seccomp. No, please. This has to fit in the save/restore model, and should be under control of the VMM. If you want to filter things using seccomp, that's fine, but also that's completely orthogonal. M. -- Without deviation from the norm, progress is not possible.
