On 07/08/2017 15:25, Mihai Donțu wrote: >> "Pause all VCPUs and stop all DMA" would definitely be a layering >> violation, so it cannot be added. >> >> "Pause all VCPUs" is basically a shortcut for many "pause the VCPU with >> a given id" commands. I lean towards omitting it. > > The case where the introspector wants to scan the guest memory needs a > KVMI_PAUSE_VM, which as discussed in a previous email, can be the > actual qemu 'pause' command. Do you mean it needs to stop DMA as well? > However, we would like to limit the > communication channels we have with the host and not use qmp (or > libvirt/etc. if qmp is not exposed). Instead, have a command that > triggers a KVM_RUN exit to qemu which in turn will call the underlying > pause function used by qmp. Would that be OK with you? You would have to send back something on completion, and then I am worried of races and deadlocks. Plus, pausing a VM at the QEMU level is a really expensive operation, so I don't think it's a good idea to let the introspector do this. You can pause all VCPUs, or use memory page permissions. >> However, now that I'm thinking of it, we need a new event for "new VCPU >> created". When the event is enabled, newly-created VCPUs should be in >> paused mode. > > I assume you are thinking about vCPU hotplug here. If so, yes, an event > that gives the introspector the chance to update its internal > bookkeeping would be useful. Yes, exactly. Paolo
