Re: [Xen-devel] [PATCH V3 5/8] iommu/arm: Add lightweight iommu_fwspec support

[Oleksandr <olekstysh@xxxxxxxxx>]

On 09.09.19 17:36, Julien Grall wrote:
> Hi Oleksandr,
Hi, Julien


> On 8/20/19 7:09 PM, Oleksandr Tyshchenko wrote:
> > From: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
> >
> > We need to have some abstract way to add new device to the IOMMU
> > based on the generic IOMMU DT bindings [1] which can be used for
> > both DT (right now) and ACPI (in future).
> >
> > For that reason we can borrow the idea used in Linux these days
> > called "iommu_fwspec". Having this in, it will be possible
> > to configure IOMMU master interfaces of the device (device IDs)
> > from a single common place and avoid keeping almost identical look-up
> > implementations in each IOMMU driver.
> >
> > There is no need to port the whole implementation of "iommu_fwspec"
> > to Xen, we could, probably, end up with a much simpler solution,
> > some "stripped down" version which fits our requirements.
> >
> > So, this patch adds the following:
> > 1. A common structure "iommu_fwspec" to hold the the per-device
> >     firmware data
> > 2. New member "iommu_fwspec" of struct device
> > 3. Functions/helpers to deal with "dev->iommu_fwspec"
> >
> > It should be noted that in comparing with original "iommu_fwspec"
> s/comparing with/comparison of/
> s/original/the Linux/ or "the original".
ok


> > Xen's variant doesn't contain some fields, which are not really
> > needed at the moment (ops, flag) and "iommu_fwnode" field was replaced
> > by "iommu_dev" to avoid porting a lot of code (to support 
> > "fwnode_handle")
> > with little benefit.
>
> It would be good to mention which version of Linux this is based on. 
> So if there is a critical bug in Linux we can port it.
It was based on current Linux master. I will mention exact version.


--
Regards,

Oleksandr Tyshchenko


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