Re: [Qemu-devel] [PATCH qemu v15 10/17] memory: Add reporting of supported page sizes

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

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On Mon, Apr 04, 2016 at 07:33:39PM +1000, 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.
> 
> As IOMMU MR represents a guest IOMMU, this uses TARGET_PAGE_SIZE
> as fallback.
> 
> 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>

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

.. with the exception of one nit:

[snip]
> diff --git a/memory.c b/memory.c
> index 95f7209..c37dbc9 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));

So here, replay requires that the get_page_sizes() callback be
populated.  However, if you move memory_region_iommu_get_page_sizes()
just above this, you can use that and have the replay fall back to
TARGET_PAGE_SIZE as well.

>      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 TARGET_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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