Re: [Qemu-devel] [PATCH qemu v14 11/18] memory: Add reporting of supported page sizes

[David Gibson <david@gibson.dropbear.id.au>]

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On Mon, Mar 21, 2016 at 06:46:59PM +1100, Alexey Kardashevskiy wrote:
> Every IOMMU has some granularity which MemoryRegionIOMMUOps::translate
> uses when translating, however this information is not available outside
> the translate context for various checks.
> 
> This adds a get_page_sizes callback to MemoryRegionIOMMUOps and
> a wrapper for it so IOMMU users (such as VFIO) can know the actual
> page size(s) used by an IOMMU.
> 
> The qemu_real_host_page_mask is used as fallback.

You're still mismatching concepts here.  The MemoryRegionIOMMUOps
represents a guest IOMMU, so falling back to qemu_real_host_page_mask
(a host property) makes no sense.  I think what you want is to fall
back to TARGET_PAGE_SIZE.

> This removes vfio_container_granularity() and uses new callback in
> memory_region_iommu_replay() when replaying IOMMU mappings on added
> IOMMU memory region.
> 
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> ---
> Changes:
> v14:
> * removed vfio_container_granularity(), changed memory_region_iommu_replay()
> 
> v4:
> * s/1<<TARGET_PAGE_BITS/qemu_real_host_page_size/
> ---
>  hw/ppc/spapr_iommu.c  |  8 ++++++++
>  hw/vfio/common.c      |  6 ------
>  include/exec/memory.h | 18 ++++++++++++++----
>  memory.c              | 17 ++++++++++++++---
>  4 files changed, 36 insertions(+), 13 deletions(-)
> 
> diff --git a/hw/ppc/spapr_iommu.c b/hw/ppc/spapr_iommu.c
> index dd662da..6dc3c45 100644
> --- a/hw/ppc/spapr_iommu.c
> +++ b/hw/ppc/spapr_iommu.c
> @@ -144,6 +144,13 @@ static void spapr_tce_table_pre_save(void *opaque)
>      tcet->mig_table = tcet->table;
>  }
>  
> +static uint64_t spapr_tce_get_page_sizes(MemoryRegion *iommu)
> +{
> +    sPAPRTCETable *tcet = container_of(iommu, sPAPRTCETable, iommu);
> +
> +    return 1ULL << tcet->page_shift;
> +}
> +
>  static void spapr_tce_table_do_enable(sPAPRTCETable *tcet);
>  static void spapr_tce_table_do_disable(sPAPRTCETable *tcet);
>  
> @@ -203,6 +210,7 @@ static const VMStateDescription vmstate_spapr_tce_table = {
>  
>  static MemoryRegionIOMMUOps spapr_iommu_ops = {
>      .translate = spapr_tce_translate_iommu,
> +    .get_page_sizes = spapr_tce_get_page_sizes,
>  };
>  
>  static int spapr_tce_table_realize(DeviceState *dev)
> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
> index d45e2db..55723c9 100644
> --- a/hw/vfio/common.c
> +++ b/hw/vfio/common.c
> @@ -313,11 +313,6 @@ out:
>      rcu_read_unlock();
>  }
>  
> -static hwaddr vfio_container_granularity(VFIOContainer *container)
> -{
> -    return (hwaddr)1 << ctz64(container->iova_pgsizes);
> -}
> -
>  static void vfio_listener_region_add(MemoryListener *listener,
>                                       MemoryRegionSection *section)
>  {
> @@ -385,7 +380,6 @@ static void vfio_listener_region_add(MemoryListener *listener,
>  
>          memory_region_register_iommu_notifier(giommu->iommu, &giommu->n);
>          memory_region_iommu_replay(giommu->iommu, &giommu->n,
> -                                   vfio_container_granularity(container),
>                                     false);
>  
>          return;
> diff --git a/include/exec/memory.h b/include/exec/memory.h
> index 2de7898..eb5ce67 100644
> --- a/include/exec/memory.h
> +++ b/include/exec/memory.h
> @@ -150,6 +150,8 @@ typedef struct MemoryRegionIOMMUOps MemoryRegionIOMMUOps;
>  struct MemoryRegionIOMMUOps {
>      /* Return a TLB entry that contains a given address. */
>      IOMMUTLBEntry (*translate)(MemoryRegion *iommu, hwaddr addr, bool is_write);
> +    /* Returns supported page sizes */
> +    uint64_t (*get_page_sizes)(MemoryRegion *iommu);
>  };
>  
>  typedef struct CoalescedMemoryRange CoalescedMemoryRange;
> @@ -573,6 +575,15 @@ static inline bool memory_region_is_iommu(MemoryRegion *mr)
>  
>  
>  /**
> + * memory_region_iommu_get_page_sizes: get supported page sizes in an iommu
> + *
> + * Returns %bitmap of supported page sizes for an iommu.
> + *
> + * @mr: the memory region being queried
> + */
> +uint64_t memory_region_iommu_get_page_sizes(MemoryRegion *mr);
> +
> +/**
>   * memory_region_notify_iommu: notify a change in an IOMMU translation entry.
>   *
>   * @mr: the memory region that was changed
> @@ -596,16 +607,15 @@ void memory_region_register_iommu_notifier(MemoryRegion *mr, Notifier *n);
>  
>  /**
>   * memory_region_iommu_replay: replay existing IOMMU translations to
> - * a notifier
> + * a notifier with the minimum page granularity returned by
> + * mr->iommu_ops->get_page_sizes().
>   *
>   * @mr: the memory region to observe
>   * @n: the notifier to which to replay iommu mappings
> - * @granularity: Minimum page granularity to replay notifications for
>   * @is_write: Whether to treat the replay as a translate "write"
>   *     through the iommu
>   */
> -void memory_region_iommu_replay(MemoryRegion *mr, Notifier *n,
> -                                hwaddr granularity, bool is_write);
> +void memory_region_iommu_replay(MemoryRegion *mr, Notifier *n, bool is_write);
>  
>  /**
>   * memory_region_unregister_iommu_notifier: unregister a notifier for
> diff --git a/memory.c b/memory.c
> index 95f7209..64a84d3 100644
> --- a/memory.c
> +++ b/memory.c
> @@ -1512,12 +1512,14 @@ void memory_region_register_iommu_notifier(MemoryRegion *mr, Notifier *n)
>      notifier_list_add(&mr->iommu_notify, n);
>  }
>  
> -void memory_region_iommu_replay(MemoryRegion *mr, Notifier *n,
> -                                hwaddr granularity, bool is_write)
> +void memory_region_iommu_replay(MemoryRegion *mr, Notifier *n, bool is_write)
>  {
> -    hwaddr addr;
> +    hwaddr addr, granularity;
>      IOMMUTLBEntry iotlb;
>  
> +    g_assert(mr->iommu_ops && mr->iommu_ops->get_page_sizes);
> +    granularity = (hwaddr)1 << ctz64(mr->iommu_ops->get_page_sizes(mr));
> +
>      for (addr = 0; addr < memory_region_size(mr); addr += granularity) {
>          iotlb = mr->iommu_ops->translate(mr, addr, is_write);
>          if (iotlb.perm != IOMMU_NONE) {
> @@ -1544,6 +1546,15 @@ void memory_region_notify_iommu(MemoryRegion *mr,
>      notifier_list_notify(&mr->iommu_notify, &entry);
>  }
>  
> +uint64_t memory_region_iommu_get_page_sizes(MemoryRegion *mr)
> +{
> +    assert(memory_region_is_iommu(mr));
> +    if (mr->iommu_ops && mr->iommu_ops->get_page_sizes) {
> +        return mr->iommu_ops->get_page_sizes(mr);
> +    }
> +    return qemu_real_host_page_size;
> +}
> +
>  void memory_region_set_log(MemoryRegion *mr, bool log, unsigned client)
>  {
>      uint8_t mask = 1 << client;

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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