Re: [Qemu-devel] [RFC PATCH] spapr_vio/spapr_iommu: Move VIO bypass where it belongs

[Alexey Kardashevskiy <aik@ozlabs.ru>]

On 01/09/2015 09:05 PM, Paolo Bonzini wrote:
> 
> 
> On 09/01/2015 02:02, Alexey Kardashevskiy wrote:
>> @@ -100,7 +98,7 @@ static const VMStateDescription vmstate_spapr_tce_table = {
>>          VMSTATE_UINT32_EQUAL(nb_table, sPAPRTCETable),
>>  
>>          /* IOMMU state */
>> -        VMSTATE_BOOL(bypass, sPAPRTCETable),
>> +        VMSTATE_UNUSED(sizeof(bool)),
> 
> sizeof(bool) can change across hosts, this needs to be the size that is
> written by put_bool in migration/vmstate.c, i.e. VMSTATE_UNUSED(1).
> 
>>          VMSTATE_VARRAY_UINT32(table, sPAPRTCETable, nb_table, 0, vmstate_info_uint64, uint64_t),
>>  
>>          VMSTATE_END_OF_LIST()
>> @@ -131,7 +129,8 @@ static int spapr_tce_table_realize(DeviceState *dev)
>>      trace_spapr_iommu_new_table(tcet->liobn, tcet, tcet->table, tcet->fd);
>>  
>>      memory_region_init_iommu(&tcet->iommu, OBJECT(dev), &spapr_iommu_ops,
>> -                             "iommu-spapr", ram_size);
>> +                             "iommu-spapr",
>> +                             (uint64_t)tcet->nb_table << tcet->page_shift);
>>  
>>      QLIST_INSERT_HEAD(&spapr_tce_tables, tcet, list);
>>  
>> @@ -191,17 +190,11 @@ MemoryRegion *spapr_tce_get_iommu(sPAPRTCETable *tcet)
>>      return &tcet->iommu;
>>  }
>>  
>> -void spapr_tce_set_bypass(sPAPRTCETable *tcet, bool bypass)
>> -{
>> -    tcet->bypass = bypass;
>> -}
>> -
>>  static void spapr_tce_reset(DeviceState *dev)
>>  {
>>      sPAPRTCETable *tcet = SPAPR_TCE_TABLE(dev);
>>      size_t table_size = tcet->nb_table * sizeof(uint64_t);
>>  
>> -    tcet->bypass = false;
>>      memset(tcet->table, 0, table_size);
>>  }
>>  
>> diff --git a/hw/ppc/spapr_vio.c b/hw/ppc/spapr_vio.c
>> index dc9e46a..a1f2316 100644
>> --- a/hw/ppc/spapr_vio.c
>> +++ b/hw/ppc/spapr_vio.c
>> @@ -322,6 +322,18 @@ static void spapr_vio_quiesce_one(VIOsPAPRDevice *dev)
>>      free_crq(dev);
>>  }
>>  
>> +static void spapr_vio_set_bypass(VIOsPAPRDevice *dev, bool bypass)
>> +{
>> +    if (dev->bypass == bypass) {
>> +        return;
>> +    }
>> +
>> +    memory_region_set_enabled(&dev->mrbypass, bypass);
>> +    memory_region_set_enabled(spapr_tce_get_iommu(dev->tcet), !bypass);
>> +
>> +    dev->bypass = bypass;
>> +}
>> +
>>  static void rtas_set_tce_bypass(PowerPCCPU *cpu, sPAPREnvironment *spapr,
>>                                  uint32_t token,
>>                                  uint32_t nargs, target_ulong args,
>> @@ -348,7 +360,7 @@ static void rtas_set_tce_bypass(PowerPCCPU *cpu, sPAPREnvironment *spapr,
>>          return;
>>      }
>>  
>> -    spapr_tce_set_bypass(dev->tcet, !!enable);
>> +    spapr_vio_set_bypass(dev, !!enable);
>>  
>>      rtas_st(rets, 0, RTAS_OUT_SUCCESS);
>>  }
>> @@ -407,6 +419,7 @@ static void spapr_vio_busdev_reset(DeviceState *qdev)
>>  
>>      dev->signal_state = 0;
>>  
>> +    spapr_vio_set_bypass(dev, false);
>>      if (pc->reset) {
>>          pc->reset(dev);
>>      }
>> @@ -456,14 +469,25 @@ static int spapr_vio_busdev_init(DeviceState *qdev)
>>  
>>      if (pc->rtce_window_size) {
>>          uint32_t liobn = SPAPR_VIO_BASE_LIOBN | dev->reg;
>> +
>> +        memory_region_init(&dev->mrroot, OBJECT(dev), "iommu-spapr-root",
>> +                           ram_size);
>> +        memory_region_init_alias(&dev->mrbypass, OBJECT(dev),
>> +                                 "iommu-spapr-bypass", get_system_memory(),
>> +                                 0, ram_size);
>> +        memory_region_add_subregion_overlap(&dev->mrroot, 0, &dev->mrbypass, 1);
>> +        address_space_init(&dev->as, &dev->mrroot, qdev->id);
>> +
>>          dev->tcet = spapr_tce_new_table(qdev, liobn,
>>                                          0,
>>                                          SPAPR_TCE_PAGE_SHIFT,
>>                                          pc->rtce_window_size >>
>>                                          SPAPR_TCE_PAGE_SHIFT, false);
>> -        address_space_init(&dev->as, spapr_tce_get_iommu(dev->tcet), qdev->id);
>> +        memory_region_add_subregion_overlap(&dev->mrroot, 0,
>> +                                            spapr_tce_get_iommu(dev->tcet), 2);
>>      }
>>  
>> +
>>      return pc->init(dev);
>>  }
>>  
>> @@ -541,6 +565,15 @@ static void spapr_vio_bridge_class_init(ObjectClass *klass, void *data)
>>      k->init = spapr_vio_bridge_init;
>>  }
>>  
>> +static int spapr_vio_post_load(void *opaque, int version_id)
>> +{
>> +    VIOsPAPRDevice *dev = VIO_SPAPR_DEVICE(opaque);
>> +
>> +    spapr_vio_set_bypass(dev, dev->bypass);
>> +
>> +    return 0;
>> +}
>> +
>>  static const TypeInfo spapr_vio_bridge_info = {
>>      .name          = "spapr-vio-bridge",
>>      .parent        = TYPE_SYS_BUS_DEVICE,
>> @@ -550,8 +583,9 @@ static const TypeInfo spapr_vio_bridge_info = {
>>  
>>  const VMStateDescription vmstate_spapr_vio = {
>>      .name = "spapr_vio",
>> -    .version_id = 1,
>> +    .version_id = 2,
>>      .minimum_version_id = 1,
> 
> I think the minimum version should be 2 as well, because migrating from
> version 1 will not set the bypass field correctly.

This why the patch is "RFC" :)

I can keep the flag in TCETable which would be a bit ugly but won't break
migration. Is there any better way to keep compatibility?



> 
> Paolo
> 
>> +    .post_load = spapr_vio_post_load,
>>      .fields = (VMStateField[]) {
>>          /* Sanity check */
>>          VMSTATE_UINT32_EQUAL(reg, VIOsPAPRDevice),
>> @@ -563,6 +597,8 @@ const VMStateDescription vmstate_spapr_vio = {
>>          VMSTATE_UINT32(crq.qsize, VIOsPAPRDevice),
>>          VMSTATE_UINT32(crq.qnext, VIOsPAPRDevice),
>>  
>> +        VMSTATE_BOOL_V(bypass, VIOsPAPRDevice, 2),
>> +
>>          VMSTATE_END_OF_LIST()
>>      },


-- 
Alexey