Re: [Qemu-devel] [RFC PATCH v1 07/10] spapr: Represent boot CPUs as spapr-cpu-core devices

[Bharata B Rao <bharata@linux.vnet.ibm.com>]

On Mon, Mar 07, 2016 at 02:45:09PM +1100, David Gibson wrote:
> On Fri, Mar 04, 2016 at 12:24:18PM +0530, Bharata B Rao wrote:
> > Initialize boot CPUs as spapr-cpu-core devices and create links from
> > machine object to these core devices. These links can be considered
> > as CPU slots in which core devices will get hot-plugged. spapr-cpu-core
> > device's slot property indicates the slot where it is plugged. Information
> > about all the CPU slots can be obtained by walking these links.
> > 
> > Also prevent topologies that have or can result in incomplete cores.
> > 
> > Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
> > ---
> >  hw/ppc/spapr.c          | 85 ++++++++++++++++++++++++++++++++++++++++++-------
> >  hw/ppc/spapr_cpu_core.c |  9 ++++++
> >  include/hw/ppc/spapr.h  |  4 +++
> >  3 files changed, 87 insertions(+), 11 deletions(-)
> > 
> > diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> > index e9d4abf..5acb612 100644
> > --- a/hw/ppc/spapr.c
> > +++ b/hw/ppc/spapr.c
> > @@ -64,6 +64,7 @@
> >  
> >  #include "hw/compat.h"
> >  #include "qemu-common.h"
> > +#include "hw/ppc/spapr_cpu_core.h"
> >  
> >  #include <libfdt.h>
> >  
> > @@ -1614,8 +1615,11 @@ static void spapr_boot_set(void *opaque, const char *boot_device,
> >      machine->boot_order = g_strdup(boot_device);
> >  }
> >  
> > -static void spapr_cpu_init(sPAPRMachineState *spapr, PowerPCCPU *cpu,
> > -                           Error **errp)
> > +/*
> > + * TODO: Check if some of these can be moved to rtas_start_cpu() where
> > + * a few other things required for hotplugged CPUs are being done.
> > + */
> > +void spapr_cpu_init(sPAPRMachineState *spapr, PowerPCCPU *cpu, Error **errp)
> >  {
> >      CPUPPCState *env = &cpu->env;
> >  
> > @@ -1643,7 +1647,6 @@ static void spapr_cpu_init(sPAPRMachineState *spapr, PowerPCCPU *cpu,
> >      }
> >  
> >      xics_cpu_setup(spapr->icp, cpu);
> > -
> >      qemu_register_reset(spapr_cpu_reset, cpu);
> >  }
> >  
> > @@ -1720,6 +1723,28 @@ static void spapr_validate_node_memory(MachineState *machine, Error **errp)
> >      }
> >  }
> >  
> > +/*
> > + * Check to see if core is being hot-plugged into an already populated slot.
> > + */
> > +static void spapr_cpu_core_allow_set_link(Object *obj, const char *name,
> > +                                          Object *val, Error **errp)
> > +{
> > +    Object *core = object_property_get_link(qdev_get_machine(), name, NULL);
> > +
> > +    /*
> > +     * Allow the link to be unset when the core is unplugged.
> > +     */
> > +    if (!val) {
> > +        return;
> > +    }
> > +
> > +    if (core) {
> > +        char *path = object_get_canonical_path(core);
> > +        error_setg(errp, "Slot %s already populated with %s", name, path);
> > +        g_free(path);
> > +    }
> > +}
> > +
> >  /* pSeries LPAR / sPAPR hardware init */
> >  static void ppc_spapr_init(MachineState *machine)
> >  {
> > @@ -1728,7 +1753,6 @@ static void ppc_spapr_init(MachineState *machine)
> >      const char *kernel_filename = machine->kernel_filename;
> >      const char *kernel_cmdline = machine->kernel_cmdline;
> >      const char *initrd_filename = machine->initrd_filename;
> > -    PowerPCCPU *cpu;
> >      PCIHostState *phb;
> >      int i;
> >      MemoryRegion *sysmem = get_system_memory();
> > @@ -1742,6 +1766,20 @@ static void ppc_spapr_init(MachineState *machine)
> >      long load_limit, fw_size;
> >      bool kernel_le = false;
> >      char *filename;
> > +    int spapr_cores = smp_cpus / smp_threads;
> > +    int spapr_max_cores = max_cpus / smp_threads;
> > +
> > +    if (smp_cpus % smp_threads) {
> > +        error_report("smp_cpus (%u) must be multiple of threads (%u)",
> > +                     smp_cpus, smp_threads);
> > +        exit(1);
> > +    }
> > +
> > +    if (max_cpus % smp_threads) {
> > +        error_report("max_cpus (%u) must be multiple of threads (%u)",
> > +                     max_cpus, smp_threads);
> > +        exit(1);
> > +    }
> >  
> >      msi_supported = true;
> >  
> > @@ -1800,13 +1838,37 @@ static void ppc_spapr_init(MachineState *machine)
> >      if (machine->cpu_model == NULL) {
> >          machine->cpu_model = kvm_enabled() ? "host" : "POWER7";
> >      }
> > -    for (i = 0; i < smp_cpus; i++) {
> > -        cpu = cpu_ppc_init(machine->cpu_model);
> > -        if (cpu == NULL) {
> > -            error_report("Unable to find PowerPC CPU definition");
> > -            exit(1);
> > +
> > +    spapr->cores = g_new0(Object *, spapr_max_cores);
> > +
> > +    for (i = 0; i < spapr_max_cores; i++) {
> > +        char name[32];
> > +
> > +        /*
> > +         * Create links from machine objects to all possible cores.
> > +         */
> > +        snprintf(name, sizeof(name), "%s[%d]", SPAPR_MACHINE_CPU_CORE_PROP, i);
> > +        object_property_add_link(OBJECT(spapr), name, TYPE_SPAPR_CPU_CORE,
> > +                                 (Object **)&spapr->cores[i],
> > +                                 spapr_cpu_core_allow_set_link,
> > +                                 OBJ_PROP_LINK_UNREF_ON_RELEASE,
> > +                                 &error_fatal);
> 
> These links no longer make sense to me.  When it was a set of links to
> the hotpluggable units on the machine, I could see why they might be
> useful.  But now that they're links explicitly to *core* which are
> only the hotpluggable units on certain platforms, I don't see why
> these are useful.
> 
> Could we maybe not create the links for now, and add them in a later
> patch if they do turn out to be useful for something?

Dropped the links part.

> 
> > +        /*
> > +         * Create cores and set link from machine object to core object for
> > +         * boot time CPUs and realize them.
> > +         */
> > +        if (i < spapr_cores) {
> > +            Object *core  = object_new(TYPE_SPAPR_CPU_CORE);
> > +
> > +            object_property_set_str(core, machine->cpu_model, "cpu_model",
> > +                                    &error_fatal);
> > +            object_property_set_int(core, smp_threads, "nr_threads",
> > +                                    &error_fatal);
> > +            object_property_set_str(core, name, CPU_CORE_SLOT_PROP,
> > +                                    &error_fatal);
> > +            object_property_set_bool(core, true, "realized", &error_fatal);
> >          }
> > -        spapr_cpu_init(spapr, cpu, &error_fatal);
> >      }
> >  
> >      if (kvm_enabled()) {
> > @@ -2259,7 +2321,8 @@ static void spapr_machine_device_unplug(HotplugHandler *hotplug_dev,
> >  static HotplugHandler *spapr_get_hotpug_handler(MachineState *machine,
> >                                               DeviceState *dev)
> >  {
> > -    if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
> > +    if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM) ||
> > +        object_dynamic_cast(OBJECT(dev), TYPE_SPAPR_CPU_CORE)) {
> >          return HOTPLUG_HANDLER(machine);
> >      }
> >      return NULL;
> > diff --git a/hw/ppc/spapr_cpu_core.c b/hw/ppc/spapr_cpu_core.c
> > index 3f3440c..9ddf3ce 100644
> > --- a/hw/ppc/spapr_cpu_core.c
> > +++ b/hw/ppc/spapr_cpu_core.c
> > @@ -17,11 +17,20 @@
> >  static int spapr_cpu_core_realize_child(Object *child, void *opaque)
> >  {
> >      Error **errp = opaque;
> > +    sPAPRMachineState *spapr = SPAPR_MACHINE(qdev_get_machine());
> > +    CPUState *cs = CPU(child);
> > +    PowerPCCPU *cpu = POWERPC_CPU(cs);
> >  
> >      object_property_set_bool(child, true, "realized", errp);
> >      if (*errp) {
> >          return 1;
> >      }
> > +
> > +    spapr_cpu_init(spapr, cpu, errp);
> > +    if (*errp) {
> > +        return 1;
> > +    }
> > +
> 
> Doesn't this change belong in the previous patch, which created the
> spapr core type?

I merged this patch with the previous one so that we have one patch
that creates spapr-cpu-core and converts boot cpus to cores.

Regards,
Bharata.