On Tue, May 05, 2015 at 04:59:51PM +1000, David Gibson wrote:
> On Fri, Apr 24, 2015 at 12:17:34PM +0530, Bharata B Rao wrote:
> > Support CPU hotplug via device-add command. Set up device tree
> > entries for the hotplugged CPU core and use the exising EPOW event
> > infrastructure to send CPU hotplug notification to the guest.
> >
> > Also support cold plugged CPUs that are specified by -device option
> > on cmdline.
> >
> > Signed-off-by: Bharata B Rao <bhar...@linux.vnet.ibm.com>
> > ---
> > hw/ppc/spapr.c | 129
> > ++++++++++++++++++++++++++++++++++++++++++++++++++
> > hw/ppc/spapr_events.c | 8 ++--
> > hw/ppc/spapr_rtas.c | 11 +++++
> > 3 files changed, 145 insertions(+), 3 deletions(-)
> >
> > diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> > index b526b7d..9b0701c 100644
> > --- a/hw/ppc/spapr.c
> > +++ b/hw/ppc/spapr.c
> > @@ -33,6 +33,7 @@
> > #include "sysemu/block-backend.h"
> > #include "sysemu/cpus.h"
> > #include "sysemu/kvm.h"
> > +#include "sysemu/device_tree.h"
> > #include "kvm_ppc.h"
> > #include "mmu-hash64.h"
> > #include "qom/cpu.h"
> > @@ -662,6 +663,17 @@ static void spapr_populate_cpu_dt(CPUState *cs, void
> > *fdt, int offset)
> > unsigned sockets = opts ? qemu_opt_get_number(opts, "sockets", 0) : 0;
> > uint32_t cpus_per_socket = sockets ? (smp_cpus / sockets) : 1;
> > uint32_t pft_size_prop[] = {0, cpu_to_be32(spapr->htab_shift)};
> > + sPAPRDRConnector *drc;
> > + sPAPRDRConnectorClass *drck;
> > + int drc_index;
> > +
> > + if (spapr->dr_cpu_enabled) {
> > + drc = spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_CPU, index);
> > + g_assert(drc);
> > + drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc);
> > + drc_index = drck->get_index(drc);
> > + _FDT((fdt_setprop_cell(fdt, offset, "ibm,my-drc-index",
> > drc_index)));
> > + }
> >
> > _FDT((fdt_setprop_cell(fdt, offset, "reg", index)));
> > _FDT((fdt_setprop_string(fdt, offset, "device_type", "cpu")));
> > @@ -1850,6 +1862,114 @@ static void spapr_nmi(NMIState *n, int cpu_index,
> > Error **errp)
> > }
> > }
> >
> > +static void *spapr_populate_hotplug_cpu_dt(DeviceState *dev, CPUState *cs,
> > + int *fdt_offset)
> > +{
> > + PowerPCCPU *cpu = POWERPC_CPU(cs);
> > + DeviceClass *dc = DEVICE_GET_CLASS(cs);
> > + int id = ppc_get_vcpu_dt_id(cpu);
> > + void *fdt;
> > + int offset, fdt_size;
> > + char *nodename;
> > +
> > + fdt = create_device_tree(&fdt_size);
> > + nodename = g_strdup_printf("%s@%x", dc->fw_name, id);
> > + offset = fdt_add_subnode(fdt, 0, nodename);
> > +
> > + spapr_populate_cpu_dt(cs, fdt, offset);
> > + g_free(nodename);
> > +
> > + *fdt_offset = offset;
> > + return fdt;
> > +}
> > +
> > +static void spapr_cpu_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
> > + Error **errp)
> > +{
> > + CPUState *cs = CPU(dev);
> > + PowerPCCPU *cpu = POWERPC_CPU(cs);
> > + int id = ppc_get_vcpu_dt_id(cpu);
> > + sPAPRDRConnector *drc =
> > + spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_CPU, id);
> > + sPAPRDRConnectorClass *drck;
> > + int smt = kvmppc_smt_threads();
> > + Error *local_err = NULL;
> > + void *fdt = NULL;
> > + int i, fdt_offset = 0;
> > +
> > + /* Set NUMA node for the added CPUs */
> > + for (i = 0; i < nb_numa_nodes; i++) {
> > + if (test_bit(cs->cpu_index, numa_info[i].node_cpu)) {
> > + cs->numa_node = i;
> > + break;
> > + }
> > + }
> > +
> > + /*
> > + * SMT threads return from here, only main thread (core) will
> > + * continue and signal hotplug event to the guest.
> > + */
> > + if ((id % smt) != 0) {
> > + return;
> > + }
>
> Couldn't you avoid this by attaching this call to the core device,
> rather than the individual vcpu thread objects?
Adding a socket device will result in realize call for that device.
Socket realizefn will call core realizefn and core realizefn will call
thread (or CPU) realizefn. device_set_realized() will call ->plug handler
for all these devices (socket, cores and threads) and that's how we
end up here even for threads.
This will be same when I get rid of socket abstraction and hot plug
cores for the same reason as above.
And calling ->plug handler in the context of threads is required
to initialize board specific CPU bits for the CPU thread that is being
realized.
>
>
> > + if (!spapr->dr_cpu_enabled) {
> > + /*
> > + * This is a cold plugged CPU but the machine doesn't support
> > + * DR. So skip the hotplug path ensuring that the CPU is brought
> > + * up online with out an associated DR connector.
> > + */
> > + return;
> > + }
> > +
> > + g_assert(drc);
> > +
> > + /*
> > + * Setup CPU DT entries only for hotplugged CPUs. For boot time or
> > + * coldplugged CPUs DT entries are setup in spapr_finalize_fdt().
> > + */
> > + if (dev->hotplugged) {
> > + fdt = spapr_populate_hotplug_cpu_dt(dev, cs, &fdt_offset);
> > + }
> > +
> > + drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc);
> > + drck->attach(drc, dev, fdt, fdt_offset, !dev->hotplugged, &local_err);
> > + if (local_err) {
> > + g_free(fdt);
> > + error_propagate(errp, local_err);
> > + return;
> > + }
> > +
> > + /*
> > + * We send hotplug notification interrupt to the guest only in case
> > + * of hotplugged CPUs.
> > + */
> > + if (dev->hotplugged) {
> > + spapr_hotplug_req_add_event(drc);
> > + } else {
> > + /*
> > + * HACK to support removal of hotplugged CPU after VM migration:
> > + *
> > + * Since we want to be able to hot-remove those coldplugged CPUs
> > + * started at boot time using -device option at the target VM, we
> > set
> > + * the right allocation_state and isolation_state for them, which
> > for
> > + * the hotplugged CPUs would be set via RTAS calls done from the
> > + * guest during hotplug.
> > + *
> > + * This allows the coldplugged CPUs started using -device option to
> > + * have the right isolation and allocation states as expected by
> > the
> > + * CPU hot removal code.
> > + *
> > + * This hack will be removed once we have DRC states migrated as
> > part
> > + * of VM migration.
> > + */
> > + drck->set_allocation_state(drc, SPAPR_DR_ALLOCATION_STATE_USABLE);
> > + drck->set_isolation_state(drc,
> > SPAPR_DR_ISOLATION_STATE_UNISOLATED);
> > + }
> > +
> > + return;
> > +}
> > +
> > static void spapr_machine_device_plug(HotplugHandler *hotplug_dev,
> > DeviceState *dev, Error **errp)
> > {
> > @@ -1858,6 +1978,15 @@ static void spapr_machine_device_plug(HotplugHandler
> > *hotplug_dev,
> > PowerPCCPU *cpu = POWERPC_CPU(cs);
> >
> > spapr_cpu_init(cpu);
> > + spapr_cpu_reset(cpu);
>
> I'm a little surprised these get called here, rather than in the
> creation / realize path of the core qdev.
These two routines (spapr_cpu_init and spapr_cpu_reset) are sPAPR or
board specific and I can't even have them as part of ppc_cpu_realizefn.
We had discussed this earlier at
http://lists.gnu.org/archive/html/qemu-devel/2015-02/msg04399.html
Regards,
Bharata.
