| Message ID | 1466145399-32209-16-git-send-email-david@gibson.dropbear.id.au (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, 17 Jun 2016 16:36:36 +1000 David Gibson <david@gibson.dropbear.id.au> wrote: > From: Bharata B Rao <bharata@linux.vnet.ibm.com> > > Remove the CPU core device by removing the underlying CPU thread devices. > Hot removal of CPU for sPAPR guests is achieved by sending the hot unplug > notification to the guest. Release the vCPU object after CPU hot unplug so > that vCPU fd can be parked and reused. > > Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com> > Signed-off-by: David Gibson <david@gibson.dropbear.id.au> [...] Bharata, Here is some notes I've made while auditing spapr cpu hotplug code. spapr_core_release() should be spapr_core_unrealize() except of machine related spapr->cores[cc->core_id / smt] = NULL; which should go to spapr_core_unplug() > +static void spapr_core_release(DeviceState *dev, void *opaque) > +{ > + sPAPRCPUCore *sc = SPAPR_CPU_CORE(OBJECT(dev)); > + const char *typename = object_class_get_name(sc->cpu_class); > + size_t size = object_type_get_instance_size(typename); > + sPAPRMachineState *spapr = SPAPR_MACHINE(qdev_get_machine()); > + sPAPRCPUCore *core = SPAPR_CPU_CORE(OBJECT(dev)); > + CPUCore *cc = CPU_CORE(dev); > + int smt = kvmppc_smt_threads(); > + int i; > + > + for (i = 0; i < cc->nr_threads; i++) { > + void *obj = sc->threads + i * size; > + DeviceState *dev = DEVICE(obj); > + CPUState *cs = CPU(dev); > + PowerPCCPU *cpu = POWERPC_CPU(cs); > + > + spapr_cpu_destroy(cpu); > + cpu_remove_sync(cs); > + object_unparent(obj); > + } > + > + spapr->cores[cc->core_id / smt] = NULL; > + > + g_free(core->threads); > + object_unparent(OBJECT(dev)); > +} > + spapr_core_[un]plug() functions belong to machine code and should be in hw/ppc/spapr.c > +void spapr_core_unplug(HotplugHandler *hotplug_dev, DeviceState *dev, > + Error **errp) > +{ > + sPAPRCPUCore *core = SPAPR_CPU_CORE(OBJECT(dev)); > + PowerPCCPU *cpu = POWERPC_CPU(core->threads); > + int id = ppc_get_vcpu_dt_id(cpu); > + sPAPRDRConnector *drc = > + spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_CPU, id); > + sPAPRDRConnectorClass *drck; > + Error *local_err = NULL; > + > + g_assert(drc); > + > + drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc); > + drck->detach(drc, dev, spapr_core_release, NULL, &local_err); Could you explain call flow during cpu unplug? My expectations were that unplug_request() handler asks for CPU removal and unplug() handler removes CPU. It's obviously messed up somehow. > + if (local_err) { > + error_propagate(errp, local_err); > + return; > + } > + > + spapr_hotplug_req_remove_by_index(drc); > +} > + > void spapr_core_plug(HotplugHandler *hotplug_dev, DeviceState *dev, > Error **errp) > { > diff --git a/include/hw/ppc/spapr_cpu_core.h b/include/hw/ppc/spapr_cpu_core.h > index 7cb0515..1c9b319 100644 > --- a/include/hw/ppc/spapr_cpu_core.h > +++ b/include/hw/ppc/spapr_cpu_core.h > @@ -31,4 +31,6 @@ void spapr_core_pre_plug(HotplugHandler *hotplug_dev, DeviceState *dev, > char *spapr_get_cpu_core_type(const char *model); > void spapr_core_plug(HotplugHandler *hotplug_dev, DeviceState *dev, > Error **errp); > +void spapr_core_unplug(HotplugHandler *hotplug_dev, DeviceState *dev, > + Error **errp); > #endif
On Thu, Jan 26, 2017 at 12:32:58PM +0100, Igor Mammedov wrote: > On Fri, 17 Jun 2016 16:36:36 +1000 > David Gibson <david@gibson.dropbear.id.au> wrote: > > > From: Bharata B Rao <bharata@linux.vnet.ibm.com> > > > > Remove the CPU core device by removing the underlying CPU thread devices. > > Hot removal of CPU for sPAPR guests is achieved by sending the hot unplug > > notification to the guest. Release the vCPU object after CPU hot unplug so > > that vCPU fd can be parked and reused. > > > > Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com> > > Signed-off-by: David Gibson <david@gibson.dropbear.id.au> > [...] > > > Bharata, > > Here is some notes I've made while auditing spapr cpu hotplug code. > > spapr_core_release() should be spapr_core_unrealize() > except of machine related > spapr->cores[cc->core_id / smt] = NULL; > which should go to spapr_core_unplug() There were some issues in calling cpu_remove_[sync] from unrealize path. I know that x86 does that way. let me remember and get back on this. > > > +static void spapr_core_release(DeviceState *dev, void *opaque) > > +{ > > + sPAPRCPUCore *sc = SPAPR_CPU_CORE(OBJECT(dev)); > > + const char *typename = object_class_get_name(sc->cpu_class); > > + size_t size = object_type_get_instance_size(typename); > > + sPAPRMachineState *spapr = SPAPR_MACHINE(qdev_get_machine()); > > + sPAPRCPUCore *core = SPAPR_CPU_CORE(OBJECT(dev)); > > + CPUCore *cc = CPU_CORE(dev); > > + int smt = kvmppc_smt_threads(); > > + int i; > > + > > + for (i = 0; i < cc->nr_threads; i++) { > > + void *obj = sc->threads + i * size; > > + DeviceState *dev = DEVICE(obj); > > + CPUState *cs = CPU(dev); > > + PowerPCCPU *cpu = POWERPC_CPU(cs); > > + > > + spapr_cpu_destroy(cpu); > > + cpu_remove_sync(cs); > > + object_unparent(obj); > > + } > > + > > + spapr->cores[cc->core_id / smt] = NULL; > > + > > + g_free(core->threads); > > + object_unparent(OBJECT(dev)); > > +} > > + > > spapr_core_[un]plug() functions belong to machine code and should > be in hw/ppc/spapr.c That's how the series started, but eventually we consolidated all core related routines in spapr_cpu_core.c > > > +void spapr_core_unplug(HotplugHandler *hotplug_dev, DeviceState *dev, > > + Error **errp) > > +{ > > + sPAPRCPUCore *core = SPAPR_CPU_CORE(OBJECT(dev)); > > + PowerPCCPU *cpu = POWERPC_CPU(core->threads); > > + int id = ppc_get_vcpu_dt_id(cpu); > > + sPAPRDRConnector *drc = > > + spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_CPU, id); > > + sPAPRDRConnectorClass *drck; > > + Error *local_err = NULL; > > + > > + g_assert(drc); > > + > > + drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc); > > + drck->detach(drc, dev, spapr_core_release, NULL, &local_err); > > Could you explain call flow during cpu unplug? In response to unplug request, spapr_core_unplug() gets called which does a detach() on the associated DRC object. The detach() registers a callback (spapr_core_release) and signals the guest about the unplug request. When the guest is ready to let go of the CPU core, DRC subsystem ends up calling the callback spapr_core_release. For each of the CPU thread objects of the core, spapr_core_release will call cpu_remove_sync() and waits for the CPU to be really removed. cpu_remove will result in CPU unrealize function being called (ppc_cpu_unrealizefn) for each of the removed CPU. After we are done waiting for all the threads' removal, the core object is ready for removal. > > My expectations were that unplug_request() handler asks for CPU removal > and unplug() handler removes CPU. > It's obviously messed up somehow. When we did CPU unplug, we didn't really implement ->unplug_request() for sPAPR. It was added later when memory unplug came in. Regards, Bharata.
On Thu, 26 Jan 2017 19:56:35 +0530 Bharata B Rao <bharata@linux.vnet.ibm.com> wrote: > On Thu, Jan 26, 2017 at 12:32:58PM +0100, Igor Mammedov wrote: > > On Fri, 17 Jun 2016 16:36:36 +1000 > > David Gibson <david@gibson.dropbear.id.au> wrote: > > > > > From: Bharata B Rao <bharata@linux.vnet.ibm.com> > > > > > > Remove the CPU core device by removing the underlying CPU thread devices. > > > Hot removal of CPU for sPAPR guests is achieved by sending the hot unplug > > > notification to the guest. Release the vCPU object after CPU hot unplug so > > > that vCPU fd can be parked and reused. > > > > > > Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com> > > > Signed-off-by: David Gibson <david@gibson.dropbear.id.au> > > [...] > > > > > > Bharata, > > > > Here is some notes I've made while auditing spapr cpu hotplug code. > > > > spapr_core_release() should be spapr_core_unrealize() > > except of machine related > > spapr->cores[cc->core_id / smt] = NULL; > > which should go to spapr_core_unplug() > > There were some issues in calling cpu_remove_[sync] from unrealize > path. I know that x86 does that way. let me remember and get back on this. on the first glance it doesn't look like there should be issues with making it spapr_core_unrealize(), but since it's way out of scope numa rework I'd leave 'fixing' it upto you. > > > > > > +static void spapr_core_release(DeviceState *dev, void *opaque) > > > +{ > > > + sPAPRCPUCore *sc = SPAPR_CPU_CORE(OBJECT(dev)); > > > + const char *typename = object_class_get_name(sc->cpu_class); > > > + size_t size = object_type_get_instance_size(typename); > > > + sPAPRMachineState *spapr = SPAPR_MACHINE(qdev_get_machine()); > > > + sPAPRCPUCore *core = SPAPR_CPU_CORE(OBJECT(dev)); > > > + CPUCore *cc = CPU_CORE(dev); > > > + int smt = kvmppc_smt_threads(); > > > + int i; > > > + > > > + for (i = 0; i < cc->nr_threads; i++) { > > > + void *obj = sc->threads + i * size; > > > + DeviceState *dev = DEVICE(obj); > > > + CPUState *cs = CPU(dev); > > > + PowerPCCPU *cpu = POWERPC_CPU(cs); > > > + > > > + spapr_cpu_destroy(cpu); > > > + cpu_remove_sync(cs); > > > + object_unparent(obj); > > > + } > > > + > > > + spapr->cores[cc->core_id / smt] = NULL; > > > + > > > + g_free(core->threads); > > > + object_unparent(OBJECT(dev)); > > > +} > > > + > > > > spapr_core_[un]plug() functions belong to machine code and should > > be in hw/ppc/spapr.c > > That's how the series started, but eventually we consolidated all > core related routines in spapr_cpu_core.c Since spapr_core_[un]plug() manage spapr machine state and not internal core state, I'd like to move them close to other machine code (spapr.c) if you don't mind. > > > > > > +void spapr_core_unplug(HotplugHandler *hotplug_dev, DeviceState *dev, > > > + Error **errp) > > > +{ > > > + sPAPRCPUCore *core = SPAPR_CPU_CORE(OBJECT(dev)); > > > + PowerPCCPU *cpu = POWERPC_CPU(core->threads); > > > + int id = ppc_get_vcpu_dt_id(cpu); > > > + sPAPRDRConnector *drc = > > > + spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_CPU, id); > > > + sPAPRDRConnectorClass *drck; > > > + Error *local_err = NULL; > > > + > > > + g_assert(drc); > > > + > > > + drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc); > > > + drck->detach(drc, dev, spapr_core_release, NULL, &local_err); > > > > Could you explain call flow during cpu unplug? > > In response to unplug request, spapr_core_unplug() gets called which > does a detach() on the associated DRC object. The detach() registers > a callback (spapr_core_release) and signals the guest about the unplug > request. > > When the guest is ready to let go of the CPU core, DRC subsystem ends up > calling the callback spapr_core_release. For each of the CPU thread objects > of the core, spapr_core_release will call cpu_remove_sync() and waits > for the CPU to be really removed. cpu_remove will result in CPU unrealize > function being called (ppc_cpu_unrealizefn) for each of the removed > CPU. > > After we are done waiting for all the threads' removal, the core object is > ready for removal. > > > > > My expectations were that unplug_request() handler asks for CPU removal > > and unplug() handler removes CPU. > > It's obviously messed up somehow. > > When we did CPU unplug, we didn't really implement ->unplug_request() for > sPAPR. It was added later when memory unplug came in. It ended up that spapr_core_unplug() is called from both ->unplug_request() and ->unplug(). Where ->unplug() is dead path that's never called. I'll send patches to fix hot-unlpug flow to conform to generic hotplug pattern ->unplug_request() -> register callback and callback ->unplug() -> release_core() > > Regards, > Bharata. > >
diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c index c444a86..1dcb9f6 100644 --- a/hw/ppc/spapr.c +++ b/hw/ppc/spapr.c @@ -2313,8 +2313,16 @@ static void spapr_machine_device_plug(HotplugHandler *hotplug_dev, static void spapr_machine_device_unplug(HotplugHandler *hotplug_dev, DeviceState *dev, Error **errp) { + sPAPRMachineClass *smc = SPAPR_MACHINE_GET_CLASS(qdev_get_machine()); + if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) { error_setg(errp, "Memory hot unplug not supported by sPAPR"); + } else if (object_dynamic_cast(OBJECT(dev), TYPE_SPAPR_CPU_CORE)) { + if (!smc->dr_cpu_enabled) { + error_setg(errp, "CPU hot unplug not supported on this machine"); + return; + } + spapr_core_unplug(hotplug_dev, dev, errp); } } diff --git a/hw/ppc/spapr_cpu_core.c b/hw/ppc/spapr_cpu_core.c index d5fa4e6..3a5da09 100644 --- a/hw/ppc/spapr_cpu_core.c +++ b/hw/ppc/spapr_cpu_core.c @@ -38,6 +38,14 @@ static void spapr_cpu_reset(void *opaque) &error_fatal); } +static void spapr_cpu_destroy(PowerPCCPU *cpu) +{ + sPAPRMachineState *spapr = SPAPR_MACHINE(qdev_get_machine()); + + xics_cpu_destroy(spapr->icp, cpu); + qemu_unregister_reset(spapr_cpu_reset, cpu); +} + void spapr_cpu_init(sPAPRMachineState *spapr, PowerPCCPU *cpu, Error **errp) { CPUPPCState *env = &cpu->env; @@ -88,6 +96,57 @@ char *spapr_get_cpu_core_type(const char *model) return core_type; } +static void spapr_core_release(DeviceState *dev, void *opaque) +{ + sPAPRCPUCore *sc = SPAPR_CPU_CORE(OBJECT(dev)); + const char *typename = object_class_get_name(sc->cpu_class); + size_t size = object_type_get_instance_size(typename); + sPAPRMachineState *spapr = SPAPR_MACHINE(qdev_get_machine()); + sPAPRCPUCore *core = SPAPR_CPU_CORE(OBJECT(dev)); + CPUCore *cc = CPU_CORE(dev); + int smt = kvmppc_smt_threads(); + int i; + + for (i = 0; i < cc->nr_threads; i++) { + void *obj = sc->threads + i * size; + DeviceState *dev = DEVICE(obj); + CPUState *cs = CPU(dev); + PowerPCCPU *cpu = POWERPC_CPU(cs); + + spapr_cpu_destroy(cpu); + cpu_remove_sync(cs); + object_unparent(obj); + } + + spapr->cores[cc->core_id / smt] = NULL; + + g_free(core->threads); + object_unparent(OBJECT(dev)); +} + +void spapr_core_unplug(HotplugHandler *hotplug_dev, DeviceState *dev, + Error **errp) +{ + sPAPRCPUCore *core = SPAPR_CPU_CORE(OBJECT(dev)); + PowerPCCPU *cpu = POWERPC_CPU(core->threads); + int id = ppc_get_vcpu_dt_id(cpu); + sPAPRDRConnector *drc = + spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_CPU, id); + sPAPRDRConnectorClass *drck; + Error *local_err = NULL; + + g_assert(drc); + + drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc); + drck->detach(drc, dev, spapr_core_release, NULL, &local_err); + if (local_err) { + error_propagate(errp, local_err); + return; + } + + spapr_hotplug_req_remove_by_index(drc); +} + void spapr_core_plug(HotplugHandler *hotplug_dev, DeviceState *dev, Error **errp) { diff --git a/include/hw/ppc/spapr_cpu_core.h b/include/hw/ppc/spapr_cpu_core.h index 7cb0515..1c9b319 100644 --- a/include/hw/ppc/spapr_cpu_core.h +++ b/include/hw/ppc/spapr_cpu_core.h @@ -31,4 +31,6 @@ void spapr_core_pre_plug(HotplugHandler *hotplug_dev, DeviceState *dev, char *spapr_get_cpu_core_type(const char *model); void spapr_core_plug(HotplugHandler *hotplug_dev, DeviceState *dev, Error **errp); +void spapr_core_unplug(HotplugHandler *hotplug_dev, DeviceState *dev, + Error **errp); #endif