Re: [RFC v3 07/15] iommu: iommu_get/put_single_reserved

[Marc Zyngier]

On Fri, 12 Feb 2016 08:13:09 +0000
Eric Auger <eric.auger@xxxxxxxxxx> wrote:

> This patch introduces iommu_get/put_single_reserved.
> 
> iommu_get_single_reserved allows to allocate a new reserved iova page
> and map it onto the physical page that contains a given physical address.
> It returns the iova that is mapped onto the provided physical address.
> Hence the physical address passed in argument does not need to be aligned.
> 
> In case a mapping already exists between both pages, the IOVA mapped
> to the PA is directly returned.
> 
> Each time an iova is successfully returned a binding ref count is
> incremented.
> 
> iommu_put_single_reserved decrements the ref count and when this latter
> is null, the mapping is destroyed and the iova is released.

I wonder if there is a requirement for the caller to find out about the
size of the mapping, or to impose a given size... MSIs clearly do not
have that requirement (this is always a 32bit value), but since
allocations usually pair address and size, I though I'd ask...

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny.