Re: [Qemu-devel] [Qemu-ppc] [PATCH qemu v13 08/16] memory: Add reporting of supported page sizes

[David Gibson]

On Tue, Mar 01, 2016 at 08:10:33PM +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.
> 
> Signed-off-by: Alexey Kardashevskiy <address@hidden>

I'm going to have to see how this gets used to really analyze it.
But, a preliminary comment:

Once this is added, it should be possible to remove the explicit page
size parameter from the iommu_replay function (since it could be
derived from the IOMMU page sizes).

> ---
> Changes:
> v4:
> * s/1<<TARGET_PAGE_BITS/qemu_real_host_page_size/
> ---
>  hw/ppc/spapr_iommu.c  |  8 ++++++++
>  include/exec/memory.h | 11 +++++++++++
>  memory.c              |  9 +++++++++
>  3 files changed, 28 insertions(+)
> 
> diff --git a/hw/ppc/spapr_iommu.c b/hw/ppc/spapr_iommu.c
> index 67a8356..4c52cf4 100644
> --- a/hw/ppc/spapr_iommu.c
> +++ b/hw/ppc/spapr_iommu.c
> @@ -143,6 +143,13 @@ static int spapr_tce_vfio_notify(MemoryRegion *iommu, 
> bool attached)
>      return spapr_tce_vfio_notify_owner(tcet->owner, tcet, attached);
>  }
>  
> +static uint64_t spapr_tce_get_page_sizes(MemoryRegion *iommu)
> +{
> +    sPAPRTCETable *tcet = container_of(iommu, sPAPRTCETable, iommu);
> +
> +    return 1ULL << tcet->page_shift;
> +}
> +
>  static int spapr_tce_table_post_load(void *opaque, int version_id)
>  {
>      sPAPRTCETable *tcet = SPAPR_TCE_TABLE(opaque);
> @@ -175,6 +182,7 @@ static const VMStateDescription vmstate_spapr_tce_table = 
> {
>  static MemoryRegionIOMMUOps spapr_iommu_ops = {
>      .translate = spapr_tce_translate_iommu,
>      .vfio_notify = spapr_tce_vfio_notify,
> +    .get_page_sizes = spapr_tce_get_page_sizes,
>  };
>  
>  static int spapr_tce_table_realize(DeviceState *dev)
> diff --git a/include/exec/memory.h b/include/exec/memory.h
> index 9f82629..c34e67c 100644
> --- a/include/exec/memory.h
> +++ b/include/exec/memory.h
> @@ -152,6 +152,8 @@ struct MemoryRegionIOMMUOps {
>      IOMMUTLBEntry (*translate)(MemoryRegion *iommu, hwaddr addr, bool 
> is_write);
>      /* Called when VFIO starts/stops using this */
>      int (*vfio_notify)(MemoryRegion *iommu, bool attached);
> +    /* Returns supported page sizes */
> +    uint64_t (*get_page_sizes)(MemoryRegion *iommu);
>  };
>  
>  typedef struct CoalescedMemoryRange CoalescedMemoryRange;
> @@ -576,6 +578,15 @@ 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
> diff --git a/memory.c b/memory.c
> index 0dd9695..5d8453d 100644
> --- a/memory.c
> +++ b/memory.c
> @@ -1462,6 +1462,15 @@ 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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