Re: [Qemu-ppc] [PATCH v2] spapr_vio/spapr_iommu: Move VIO bypass where it belongs

[Alexey Kardashevskiy]

On 01/27/2015 05:13 PM, Alexey Kardashevskiy wrote:
> Instead of tweaking a TCE table device by adding there a bypass flag,
> let's add an alias to RAM and IOMMU memory region, and enable/disable
> those according to the selected bypass mode.
> This way IOMMU memory region can have size of the actual window rather
> than ram_size which is essential for upcoming DDW support.
> 
> This moves bypass logic to VIO layer and keeps @bypass flag in TCE table
> for migration compatibility only. This replaces spapr_tce_set_bypass()
> calls with explicit assignment to avoid confusion as the function could
> do something more that just syncing the @bypass flag.
> 
> Signed-off-by: Alexey Kardashevskiy <address@hidden>
> ---
> Changes:
> v2:
> * kept @bypass in sPAPRTCETable not to break migration
> ---
>  hw/ppc/spapr_iommu.c       | 13 +++----------
>  hw/ppc/spapr_vio.c         | 39 +++++++++++++++++++++++++++++++++++++--
>  include/hw/ppc/spapr.h     |  1 -
>  include/hw/ppc/spapr_vio.h |  2 ++
>  4 files changed, 42 insertions(+), 13 deletions(-)
> 
> diff --git a/hw/ppc/spapr_iommu.c b/hw/ppc/spapr_iommu.c
> index da47474..a7b027a 100644
> --- a/hw/ppc/spapr_iommu.c
> +++ b/hw/ppc/spapr_iommu.c
> @@ -72,9 +72,7 @@ static IOMMUTLBEntry spapr_tce_translate_iommu(MemoryRegion 
> *iommu, hwaddr addr,
>          .perm = IOMMU_NONE,
>      };
>  
> -    if (tcet->bypass) {
> -        ret.perm = IOMMU_RW;
> -    } else if ((addr >> tcet->page_shift) < tcet->nb_table) {
> +    if ((addr >> tcet->page_shift) < tcet->nb_table) {
>          /* Check if we are in bound */
>          hwaddr page_mask = IOMMU_PAGE_MASK(tcet->page_shift);
>  
> @@ -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..b65eb11 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->tcet) {
> +        return;
> +    }
> +
> +    memory_region_set_enabled(&dev->mrbypass, bypass);
> +    memory_region_set_enabled(spapr_tce_get_iommu(dev->tcet), !bypass);
> +
> +    dev->tcet->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);
>      }
> @@ -456,12 +469,22 @@ 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 +564,17 @@ 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);
> +
> +    if (dev->tcet) {
> +        spapr_vio_set_bypass(dev, dev->tcet->bypass);


Oh. Just realized that if VIOsPAPRDevice migrated before sPAPRTCETable,
@bypass will always be false. So please ignore this patch for now :(




> +    }
> +
> +    return 0;
> +}
> +
>  static const TypeInfo spapr_vio_bridge_info = {
>      .name          = "spapr-vio-bridge",
>      .parent        = TYPE_SYS_BUS_DEVICE,
> @@ -552,6 +586,7 @@ const VMStateDescription vmstate_spapr_vio = {
>      .name = "spapr_vio",
>      .version_id = 1,
>      .minimum_version_id = 1,
> +    .post_load = spapr_vio_post_load,
>      .fields = (VMStateField[]) {
>          /* Sanity check */
>          VMSTATE_UINT32_EQUAL(reg, VIOsPAPRDevice),
> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> index 716bff4..ebc7e51 100644
> --- a/include/hw/ppc/spapr.h
> +++ b/include/hw/ppc/spapr.h
> @@ -475,7 +475,6 @@ sPAPRTCETable *spapr_tce_new_table(DeviceState *owner, 
> uint32_t liobn,
>                                     uint32_t nb_table,
>                                     bool vfio_accel);
>  MemoryRegion *spapr_tce_get_iommu(sPAPRTCETable *tcet);
> -void spapr_tce_set_bypass(sPAPRTCETable *tcet, bool bypass);
>  int spapr_dma_dt(void *fdt, int node_off, const char *propname,
>                   uint32_t liobn, uint64_t window, uint32_t size);
>  int spapr_tcet_dma_dt(void *fdt, int node_off, const char *propname,
> diff --git a/include/hw/ppc/spapr_vio.h b/include/hw/ppc/spapr_vio.h
> index 46edc2a..6ad55d1 100644
> --- a/include/hw/ppc/spapr_vio.h
> +++ b/include/hw/ppc/spapr_vio.h
> @@ -64,6 +64,8 @@ struct VIOsPAPRDevice {
>      target_ulong signal_state;
>      VIOsPAPR_CRQ crq;
>      AddressSpace as;
> +    MemoryRegion mrroot;
> +    MemoryRegion mrbypass;
>      sPAPRTCETable *tcet;
>  };
>  
> 


-- 
Alexey