On Tue, May 05, 2015 at 05:28:38PM +1000, David Gibson wrote:
> On Fri, Apr 24, 2015 at 12:17:42PM +0530, Bharata B Rao wrote:
> > Support hot removal of CPU for sPAPR guests by sending the hot unplug
> > notification to the guest via EPOW interrupt. Release the vCPU object
> > after CPU hot unplug so that vCPU fd can be parked and reused.
> >
> > Signed-off-by: Bharata B Rao <bhar...@linux.vnet.ibm.com>
> > ---
> > hw/ppc/spapr.c | 101
> > +++++++++++++++++++++++++++++++++++++++++++-
> > target-ppc/translate_init.c | 10 +++++
> > 2 files changed, 110 insertions(+), 1 deletion(-)
> >
> > diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> > index 9b0701c..910a50f 100644
> > --- a/hw/ppc/spapr.c
> > +++ b/hw/ppc/spapr.c
> > @@ -1481,6 +1481,12 @@ static void spapr_cpu_init(PowerPCCPU *cpu)
> > qemu_register_reset(spapr_cpu_reset, cpu);
> > }
> >
> > +static void spapr_cpu_destroy(PowerPCCPU *cpu)
> > +{
> > + xics_cpu_destroy(spapr->icp, cpu);
> > + qemu_unregister_reset(spapr_cpu_reset, cpu);
> > +}
> > +
> > /* pSeries LPAR / sPAPR hardware init */
> > static void ppc_spapr_init(MachineState *machine)
> > {
> > @@ -1883,6 +1889,24 @@ static void
> > *spapr_populate_hotplug_cpu_dt(DeviceState *dev, CPUState *cs,
> > return fdt;
> > }
> >
> > +static void spapr_cpu_release(DeviceState *dev, void *opaque)
> > +{
> > + CPUState *cs;
> > + int i;
> > + int id = ppc_get_vcpu_dt_id(POWERPC_CPU(CPU(dev)));
> > +
> > + for (i = id; i < id + smp_threads; i++) {
> > + CPU_FOREACH(cs) {
> > + PowerPCCPU *cpu = POWERPC_CPU(cs);
> > +
> > + if (i == ppc_get_vcpu_dt_id(cpu)) {
> > + spapr_cpu_destroy(cpu);
> > + cpu_remove(cs);
> > + }
> > + }
> > + }
> > +}
> > +
> > static void spapr_cpu_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
> > Error **errp)
> > {
> > @@ -1970,6 +1994,59 @@ static void spapr_cpu_plug(HotplugHandler
> > *hotplug_dev, DeviceState *dev,
> > return;
> > }
> >
> > +static int spapr_cpu_unplug(Object *obj, void *opaque)
> > +{
> > + Error **errp = opaque;
> > + DeviceState *dev = DEVICE(obj);
> > + CPUState *cs = CPU(dev);
> > + PowerPCCPU *cpu = POWERPC_CPU(cs);
> > + int id = ppc_get_vcpu_dt_id(cpu);
> > + int smt = kvmppc_smt_threads();
> > + sPAPRDRConnector *drc =
> > + spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_CPU, id);
> > + sPAPRDRConnectorClass *drck;
> > + Error *local_err = NULL;
> > +
> > + /*
> > + * SMT threads return from here, only main thread (core) will
> > + * continue and signal hot unplug event to the guest.
> > + */
> > + if ((id % smt) != 0) {
> > + return 0;
> > + }
>
> As with the in-plug side couldn't this be done more naturally by
> attaching this function to the cpu core object rather than the thread?
When I switch to core level addition in the next version, I will see
how best this can be handled.
>
> > + g_assert(drc);
> > +
> > + drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc);
> > + drck->detach(drc, dev, spapr_cpu_release, NULL, &local_err);
> > + if (local_err) {
> > + error_propagate(errp, local_err);
> > + return -1;
> > + }
> > +
> > + /*
> > + * In addition to hotplugged CPUs, send the hot-unplug notification
> > + * interrupt to the guest for coldplugged CPUs started via -device
> > + * option too.
> > + */
> > + spapr_hotplug_req_remove_event(drc);
>
> Um.. doesn't the remove notification need to go *before* the
> "physical" unplug? Along with a wait for acknowledgement from the
> guest?
If I am reading it right, PCI hotplug is also following the same order
(detach followed by guest notification).
Let me experiment with this in the next version.
Regards,
Bharata.
