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Re: [Qemu-devel] [PATCH] ppc/xics: split ICP into icp-base and icp class


From: Greg Kurz
Subject: Re: [Qemu-devel] [PATCH] ppc/xics: split ICP into icp-base and icp class
Date: Wed, 11 Jul 2018 11:26:41 +0200

On Wed, 11 Jul 2018 11:28:02 +1000
David Gibson <address@hidden> wrote:

> On Tue, Jul 10, 2018 at 05:55:14PM +0200, Greg Kurz wrote:
> > Recent cleanup in commit a028dd423ee6 causes QEMU to crash during CPU
> > hotplug:
> > 
> > (qemu) device_add host-spapr-cpu-core,id=core1,core-id=1
> > Segmentation fault (core dumped)
> > 
> > When the hotplug path tries to reset the ICP device, we end
> > up calling:
> > 
> > static void icp_kvm_reset(DeviceState *dev)
> > {
> >     ICPStateClass *icpc = ICP_GET_CLASS(dev);
> > 
> >     icpc->parent_reset(dev);
> > 
> > but icpc->parent_reset is NULL.  
> 
> This seems terribly complex to address this symptom.  Couldn't we just
> do a
> 
>       if (icpc->parent_reset)
>               icpc->parent_reset(dev);
> 
> ?
> 

This would certainly avoid the SEGV but this would mean that
we skip icp_reset() for hot plugged ICPs... and it doesn't
address the fact that icp_kvm_reset() is never called for cold
plugged ones.

Commit a028dd423ee6 inverted the control: icp_reset() no
longer calls per-ICP type reset function. It is up to each
type to call icp_reset().

Maybe I can split the patch to ease review. But if you're really
seeking simplicity, the best call is probably to simply revert
a028dd423ee6 at this point.

> > Indeed, the TYPE_ICP class doesn't implement DeviceClass::reset, but
> > rather directly registers a reset handler with qemu_register_reset().
> > This is done this way because ICPs aren't SysBus devices but we want
> > machine reset to reset them anyway (commit 7ea6e0671754).
> > 
> > The crash also proves that ipc_kvm_reset() is obviously not called for
> > cold plugged devices, ie, TYPE_ICP_KVM should register its own handler
> > with qemu_register_reset().
> > 
> > The motivation of commit a028dd423ee6 to have cleaner object patterns
> > is good, but it means that all specialized ICP types should register
> > their own reset handler to be called at machine reset.
> > 
> > So this patchs converts the current TYPE_ICP class into an abstract
> > TYPE_ICP_BASE class that implements DeviceClass::reset instead of
> > calling qemu_register_reset().
> > 
> > The _new_ TYPE_ICP class is derived from TYPE_ICP_BASE to cover the
> > the pseries.kernel-irqchip=off case. It merely registers a reset
> > handler with qemu_register_reset(). Its device class functions
> > are renamed as icp_simple_* to avoid confusion with the base class.
> > 
> > All other specialized ICP types are also converted to register their
> > own reset handler as well.
> > 
> > This matches what we already have with ICS.
> > 
> > Since we support CPU hot unplug with spapr, unrealize functions
> > are added to TYPE_ICP and TYPE_ICP_KVM so that they can call
> > qemu_unregister_reset().
> > 
> > Reported-by: Satheesh Rajendran <address@hidden>
> > Fixes: a028dd423ee6dfd091a8c63028240832bf10f671
> > Signed-off-by: Greg Kurz <address@hidden>
> > ---
> > 
> > I've successfully tested the following:
> > - pseries with in-kernel XICS
> > - pseries with emulated XICS
> > - powernv
> > - migration of pseries, including migration to QEMU 2.12 and back
> > ---
> >  hw/intc/xics.c        |   97 
> > ++++++++++++++++++++++++++++++++++++++++---------
> >  hw/intc/xics_kvm.c    |   27 +++++++++++---
> >  hw/intc/xics_pnv.c    |   27 +++++++++++---
> >  include/hw/ppc/xics.h |   12 ++++--
> >  4 files changed, 129 insertions(+), 34 deletions(-)
> > 
> > diff --git a/hw/intc/xics.c b/hw/intc/xics.c
> > index b9f1a3c97214..b478b9120062 100644
> > --- a/hw/intc/xics.c
> > +++ b/hw/intc/xics.c
> > @@ -40,7 +40,7 @@
> >  
> >  void icp_pic_print_info(ICPState *icp, Monitor *mon)
> >  {
> > -    ICPStateClass *icpc = ICP_GET_CLASS(icp);
> > +    ICPStateClass *icpc = ICP_BASE_GET_CLASS(icp);
> >      int cpu_index = icp->cs ? icp->cs->cpu_index : -1;
> >  
> >      if (!icp->output) {
> > @@ -255,7 +255,7 @@ static void icp_irq(ICSState *ics, int server, int nr, 
> > uint8_t priority)
> >  static int icp_dispatch_pre_save(void *opaque)
> >  {
> >      ICPState *icp = opaque;
> > -    ICPStateClass *info = ICP_GET_CLASS(icp);
> > +    ICPStateClass *info = ICP_BASE_GET_CLASS(icp);
> >  
> >      if (info->pre_save) {
> >          info->pre_save(icp);
> > @@ -267,7 +267,7 @@ static int icp_dispatch_pre_save(void *opaque)
> >  static int icp_dispatch_post_load(void *opaque, int version_id)
> >  {
> >      ICPState *icp = opaque;
> > -    ICPStateClass *info = ICP_GET_CLASS(icp);
> > +    ICPStateClass *info = ICP_BASE_GET_CLASS(icp);
> >  
> >      if (info->post_load) {
> >          return info->post_load(icp, version_id);
> > @@ -291,9 +291,9 @@ static const VMStateDescription vmstate_icp_server = {
> >      },
> >  };
> >  
> > -static void icp_reset(void *dev)
> > +static void icp_base_reset(DeviceState *dev)
> >  {
> > -    ICPState *icp = ICP(dev);
> > +    ICPState *icp = ICP_BASE(dev);
> >  
> >      icp->xirr = 0;
> >      icp->pending_priority = 0xff;
> > @@ -303,9 +303,9 @@ static void icp_reset(void *dev)
> >      qemu_set_irq(icp->output, 0);
> >  }
> >  
> > -static void icp_realize(DeviceState *dev, Error **errp)
> > +static void icp_base_realize(DeviceState *dev, Error **errp)
> >  {
> > -    ICPState *icp = ICP(dev);
> > +    ICPState *icp = ICP_BASE(dev);
> >      PowerPCCPU *cpu;
> >      CPUPPCState *env;
> >      Object *obj;
> > @@ -345,31 +345,91 @@ static void icp_realize(DeviceState *dev, Error 
> > **errp)
> >          return;
> >      }
> >  
> > -    qemu_register_reset(icp_reset, dev);
> >      vmstate_register(NULL, icp->cs->cpu_index, &vmstate_icp_server, icp);
> >  }
> >  
> > -static void icp_unrealize(DeviceState *dev, Error **errp)
> > +static void icp_base_unrealize(DeviceState *dev, Error **errp)
> >  {
> > -    ICPState *icp = ICP(dev);
> > +    ICPState *icp = ICP_BASE(dev);
> >  
> >      vmstate_unregister(NULL, &vmstate_icp_server, icp);
> > -    qemu_unregister_reset(icp_reset, dev);
> >  }
> >  
> > -static void icp_class_init(ObjectClass *klass, void *data)
> > +static void icp_base_class_init(ObjectClass *klass, void *data)
> >  {
> >      DeviceClass *dc = DEVICE_CLASS(klass);
> >  
> > -    dc->realize = icp_realize;
> > -    dc->unrealize = icp_unrealize;
> > +    dc->realize = icp_base_realize;
> > +    dc->unrealize = icp_base_unrealize;
> > +    dc->reset = icp_base_reset;
> >  }
> >  
> > -static const TypeInfo icp_info = {
> > -    .name = TYPE_ICP,
> > +static const TypeInfo icp_base_info = {
> > +    .name = TYPE_ICP_BASE,
> >      .parent = TYPE_DEVICE,
> >      .instance_size = sizeof(ICPState),
> > -    .class_init = icp_class_init,
> > +    .class_init = icp_base_class_init,
> > +    .class_size = sizeof(ICPStateClass),
> > +    .abstract = true,
> > +};
> > +
> > +static void icp_simple_reset(DeviceState *dev)
> > +{
> > +    ICPStateClass *icpc = ICP_BASE_GET_CLASS(dev);
> > +
> > +    icpc->parent_reset(dev);
> > +}
> > +
> > +static void icp_simple_reset_handler(void *dev)
> > +{
> > +    icp_simple_reset(dev);
> > +}
> > +
> > +static void icp_simple_realize(DeviceState *dev, Error **errp)
> > +{
> > +    ICPStateClass *icpc = ICP_BASE_GET_CLASS(dev);
> > +    Error *local_err = NULL;
> > +
> > +    icpc->parent_realize(dev, &local_err);
> > +    if (local_err) {
> > +        error_propagate(errp, local_err);
> > +        return;
> > +    }
> > +
> > +    qemu_register_reset(icp_simple_reset_handler, dev);
> > +}
> > +
> > +static void icp_simple_unrealize(DeviceState *dev, Error **errp)
> > +{
> > +    ICPStateClass *icpc = ICP_BASE_GET_CLASS(dev);
> > +    Error *local_err = NULL;
> > +
> > +    icpc->parent_unrealize(dev, &local_err);
> > +    if (local_err) {
> > +        error_propagate(errp, local_err);
> > +        return;
> > +    }
> > +
> > +    qemu_unregister_reset(icp_simple_reset_handler, dev);
> > +}
> > +
> > +static void icp_simple_class_init(ObjectClass *klass, void *data)
> > +{
> > +    DeviceClass *dc = DEVICE_CLASS(klass);
> > +    ICPStateClass *icpc = ICP_BASE_CLASS(klass);
> > +
> > +    device_class_set_parent_realize(dc, icp_simple_realize,
> > +                                    &icpc->parent_realize);
> > +    device_class_set_parent_unrealize(dc, icp_simple_unrealize,
> > +                                      &icpc->parent_unrealize);
> > +    device_class_set_parent_reset(dc, icp_simple_reset, 
> > &icpc->parent_reset);
> > +}
> > +
> > +static const TypeInfo icp_simple_info = {
> > +    .name = TYPE_ICP,
> > +    .parent = TYPE_ICP_BASE,
> > +    .instance_size = sizeof(ICPState),
> > +    .class_init = icp_simple_class_init,
> >      .class_size = sizeof(ICPStateClass),
> >  };
> >  
> > @@ -744,7 +804,8 @@ static void xics_register_types(void)
> >  {
> >      type_register_static(&ics_simple_info);
> >      type_register_static(&ics_base_info);
> > -    type_register_static(&icp_info);
> > +    type_register_static(&icp_simple_info);
> > +    type_register_static(&icp_base_info);
> >      type_register_static(&xics_fabric_info);
> >  }
> >  
> > diff --git a/hw/intc/xics_kvm.c b/hw/intc/xics_kvm.c
> > index 30c3769a2084..72e700677059 100644
> > --- a/hw/intc/xics_kvm.c
> > +++ b/hw/intc/xics_kvm.c
> > @@ -116,17 +116,22 @@ static int icp_set_kvm_state(ICPState *icp, int 
> > version_id)
> >  
> >  static void icp_kvm_reset(DeviceState *dev)
> >  {
> > -    ICPStateClass *icpc = ICP_GET_CLASS(dev);
> > +    ICPStateClass *icpc = ICP_BASE_GET_CLASS(dev);
> >  
> >      icpc->parent_reset(dev);
> >  
> > -    icp_set_kvm_state(ICP(dev), 1);
> > +    icp_set_kvm_state(ICP_BASE(dev), 1);
> > +}
> > +
> > +static void icp_kvm_reset_handler(void *dev)
> > +{
> > +    icp_kvm_reset(dev);
> >  }
> >  
> >  static void icp_kvm_realize(DeviceState *dev, Error **errp)
> >  {
> > -    ICPState *icp = ICP(dev);
> > -    ICPStateClass *icpc = ICP_GET_CLASS(icp);
> > +    ICPState *icp = ICP_BASE(dev);
> > +    ICPStateClass *icpc = ICP_BASE_GET_CLASS(icp);
> >      Error *local_err = NULL;
> >      CPUState *cs;
> >      KVMEnabledICP *enabled_icp;
> > @@ -166,15 +171,25 @@ static void icp_kvm_realize(DeviceState *dev, Error 
> > **errp)
> >      enabled_icp = g_malloc(sizeof(*enabled_icp));
> >      enabled_icp->vcpu_id = vcpu_id;
> >      QLIST_INSERT_HEAD(&kvm_enabled_icps, enabled_icp, node);
> > +    qemu_register_reset(icp_kvm_reset_handler, icp);
> > +}
> > +
> > +static void icp_kvm_unrealize(DeviceState *dev, Error **errp)
> > +{
> > +    ICPState *icp = ICP_BASE(dev);
> > +
> > +    qemu_unregister_reset(icp_kvm_reset_handler, icp);
> >  }
> >  
> >  static void icp_kvm_class_init(ObjectClass *klass, void *data)
> >  {
> >      DeviceClass *dc = DEVICE_CLASS(klass);
> > -    ICPStateClass *icpc = ICP_CLASS(klass);
> > +    ICPStateClass *icpc = ICP_BASE_CLASS(klass);
> >  
> >      device_class_set_parent_realize(dc, icp_kvm_realize,
> >                                      &icpc->parent_realize);
> > +    device_class_set_parent_unrealize(dc, icp_kvm_unrealize,
> > +                                      &icpc->parent_unrealize);
> >      device_class_set_parent_reset(dc, icp_kvm_reset,
> >                                    &icpc->parent_reset);
> >  
> > @@ -185,7 +200,7 @@ static void icp_kvm_class_init(ObjectClass *klass, void 
> > *data)
> >  
> >  static const TypeInfo icp_kvm_info = {
> >      .name = TYPE_KVM_ICP,
> > -    .parent = TYPE_ICP,
> > +    .parent = TYPE_ICP_BASE,
> >      .instance_size = sizeof(ICPState),
> >      .class_init = icp_kvm_class_init,
> >      .class_size = sizeof(ICPStateClass),
> > diff --git a/hw/intc/xics_pnv.c b/hw/intc/xics_pnv.c
> > index fa48505f365e..a29ccb68df73 100644
> > --- a/hw/intc/xics_pnv.c
> > +++ b/hw/intc/xics_pnv.c
> > @@ -33,7 +33,7 @@
> >  
> >  static uint64_t pnv_icp_read(void *opaque, hwaddr addr, unsigned width)
> >  {
> > -    ICPState *icp = ICP(opaque);
> > +    ICPState *icp = ICP_BASE(opaque);
> >      PnvICPState *picp = PNV_ICP(opaque);
> >      bool byte0 = (width == 1 && (addr & 0x3) == 0);
> >      uint64_t val = 0xffffffff;
> > @@ -96,7 +96,7 @@ bad_access:
> >  static void pnv_icp_write(void *opaque, hwaddr addr, uint64_t val,
> >                                unsigned width)
> >  {
> > -    ICPState *icp = ICP(opaque);
> > +    ICPState *icp = ICP_BASE(opaque);
> >      PnvICPState *picp = PNV_ICP(opaque);
> >      bool byte0 = (width == 1 && (addr & 0x3) == 0);
> >  
> > @@ -145,6 +145,18 @@ bad_access:
> >      }
> >  }
> >  
> > +static void pnv_icp_reset(DeviceState *dev)
> > +{
> > +    ICPStateClass *icpc = ICP_BASE_GET_CLASS(dev);
> > +
> > +    icpc->parent_reset(dev);
> > +}
> > +
> > +static void pnv_icp_reset_handler(void *dev)
> > +{
> > +    pnv_icp_reset(dev);
> > +}
> > +
> >  static const MemoryRegionOps pnv_icp_ops = {
> >      .read = pnv_icp_read,
> >      .write = pnv_icp_write,
> > @@ -161,9 +173,9 @@ static const MemoryRegionOps pnv_icp_ops = {
> >  
> >  static void pnv_icp_realize(DeviceState *dev, Error **errp)
> >  {
> > -    ICPState *icp = ICP(dev);
> > +    ICPState *icp = ICP_BASE(dev);
> >      PnvICPState *pnv_icp = PNV_ICP(icp);
> > -    ICPStateClass *icpc = ICP_GET_CLASS(icp);
> > +    ICPStateClass *icpc = ICP_BASE_GET_CLASS(icp);
> >      Error *local_err = NULL;
> >  
> >      icpc->parent_realize(dev, &local_err);
> > @@ -174,21 +186,24 @@ static void pnv_icp_realize(DeviceState *dev, Error 
> > **errp)
> >  
> >      memory_region_init_io(&pnv_icp->mmio, OBJECT(icp), &pnv_icp_ops,
> >                            icp, "icp-thread", 0x1000);
> > +    qemu_register_reset(pnv_icp_reset_handler, icp);
> >  }
> >  
> >  static void pnv_icp_class_init(ObjectClass *klass, void *data)
> >  {
> >      DeviceClass *dc = DEVICE_CLASS(klass);
> > -    ICPStateClass *icpc = ICP_CLASS(klass);
> > +    ICPStateClass *icpc = ICP_BASE_CLASS(klass);
> >  
> >      device_class_set_parent_realize(dc, pnv_icp_realize,
> >                                      &icpc->parent_realize);
> > +    device_class_set_parent_reset(dc, pnv_icp_reset,
> > +                                  &icpc->parent_reset);
> >      dc->desc = "PowerNV ICP";
> >  }
> >  
> >  static const TypeInfo pnv_icp_info = {
> >      .name          = TYPE_PNV_ICP,
> > -    .parent        = TYPE_ICP,
> > +    .parent        = TYPE_ICP_BASE,
> >      .instance_size = sizeof(PnvICPState),
> >      .class_init    = pnv_icp_class_init,
> >      .class_size    = sizeof(ICPStateClass),
> > diff --git a/include/hw/ppc/xics.h b/include/hw/ppc/xics.h
> > index 6ac8a9392da6..6a2e45997f8f 100644
> > --- a/include/hw/ppc/xics.h
> > +++ b/include/hw/ppc/xics.h
> > @@ -48,6 +48,9 @@ typedef struct ICSState ICSState;
> >  typedef struct ICSIRQState ICSIRQState;
> >  typedef struct XICSFabric XICSFabric;
> >  
> > +#define TYPE_ICP_BASE "icp-base"
> > +#define ICP_BASE(obj) OBJECT_CHECK(ICPState, (obj), TYPE_ICP_BASE)
> > +
> >  #define TYPE_ICP "icp"
> >  #define ICP(obj) OBJECT_CHECK(ICPState, (obj), TYPE_ICP)
> >  
> > @@ -57,15 +60,16 @@ typedef struct XICSFabric XICSFabric;
> >  #define TYPE_PNV_ICP "pnv-icp"
> >  #define PNV_ICP(obj) OBJECT_CHECK(PnvICPState, (obj), TYPE_PNV_ICP)
> >  
> > -#define ICP_CLASS(klass) \
> > -     OBJECT_CLASS_CHECK(ICPStateClass, (klass), TYPE_ICP)
> > -#define ICP_GET_CLASS(obj) \
> > -     OBJECT_GET_CLASS(ICPStateClass, (obj), TYPE_ICP)
> > +#define ICP_BASE_CLASS(klass) \
> > +     OBJECT_CLASS_CHECK(ICPStateClass, (klass), TYPE_ICP_BASE)
> > +#define ICP_BASE_GET_CLASS(obj) \
> > +     OBJECT_GET_CLASS(ICPStateClass, (obj), TYPE_ICP_BASE)
> >  
> >  struct ICPStateClass {
> >      DeviceClass parent_class;
> >  
> >      DeviceRealize parent_realize;
> > +    DeviceUnrealize parent_unrealize;
> >      DeviceReset parent_reset;
> >  
> >      void (*pre_save)(ICPState *icp);
> >   
> 

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