Re: [PATCH v9 2/9] memory: Add interface to set iommu page size mask

[Auger Eric <eric.auger@redhat.com>]

Hi Bharat,
On 3/23/20 9:46 AM, Bharat Bhushan wrote:
> Allow to set page size mask to be supported by iommu.
by iommu memory region. I mean this is not global to the IOMMU.
> This is required to expose page size mask compatible with
> host with virtio-iommu.
> 
> Signed-off-by: Bharat Bhushan <bbhushan2@marvell.com>
> ---
>  include/exec/memory.h | 20 ++++++++++++++++++++
>  memory.c              | 10 ++++++++++
>  2 files changed, 30 insertions(+)
> 
> diff --git a/include/exec/memory.h b/include/exec/memory.h
> index e85b7de99a..063c424854 100644
> --- a/include/exec/memory.h
> +++ b/include/exec/memory.h
> @@ -355,6 +355,16 @@ typedef struct IOMMUMemoryRegionClass {
>       * @iommu: the IOMMUMemoryRegion
>       */
>      int (*num_indexes)(IOMMUMemoryRegion *iommu);
> +
> +    /*
> +     * Set supported IOMMU page size
> +     *
> +     * Optional method: if this is supported then set page size that
> +     * can be supported by IOMMU. This is called to set supported page
> +     * size as per host Linux.
What about: If supported, allows to restrict the page size mask that can
be supported with a given IOMMU memory region. For example, this allows
to propagate host physical IOMMU page size mask limitations to the
virtual IOMMU (vfio assignment with virtual iommu).
> +     */
> +     void (*iommu_set_page_size_mask)(IOMMUMemoryRegion *iommu,
> +                                      uint64_t page_size_mask);
>  } IOMMUMemoryRegionClass;
>  
>  typedef struct CoalescedMemoryRange CoalescedMemoryRange;
> @@ -1363,6 +1373,16 @@ int memory_region_iommu_attrs_to_index(IOMMUMemoryRegion *iommu_mr,
>   */
>  int memory_region_iommu_num_indexes(IOMMUMemoryRegion *iommu_mr);
>  
> +/**
> + * memory_region_iommu_set_page_size_mask: set the supported pages
> + * size by iommu.
supported page sizes for a given IOMMU memory region
> + *
> + * @iommu_mr: the memory region
IOMMU memory region
> + * @page_size_mask: supported page size mask
> + */
> +void memory_region_iommu_set_page_size_mask(IOMMUMemoryRegion *iommu_mr,
> +                                            uint64_t page_size_mask);
> +
>  /**
>   * memory_region_name: get a memory region's name
>   *
> diff --git a/memory.c b/memory.c
> index aeaa8dcc9e..14c8783084 100644
> --- a/memory.c
> +++ b/memory.c
> @@ -1833,6 +1833,16 @@ static int memory_region_update_iommu_notify_flags(IOMMUMemoryRegion *iommu_mr,
>      return ret;
>  }
>  
> +void memory_region_iommu_set_page_size_mask(IOMMUMemoryRegion *iommu_mr,
> +                                            uint64_t page_size_mask)
> +{
> +    IOMMUMemoryRegionClass *imrc = IOMMU_MEMORY_REGION_GET_CLASS(iommu_mr);
> +
> +    if (imrc->iommu_set_page_size_mask) {
> +        imrc->iommu_set_page_size_mask(iommu_mr, page_size_mask);
Shouldn't it return an int in case the setting cannot be applied?
> +    }
> +}
> +
>  int memory_region_register_iommu_notifier(MemoryRegion *mr,
>                                            IOMMUNotifier *n, Error **errp)
>  {
> 
Thanks
Eric