Re: [Xen-devel] [PATCH V5] xen/arm: Restrict "p2m_ipa_bits" according to the IOMMU requirements

[Oleksandr <olekstysh@xxxxxxxxx>]

On 27.09.19 15:38, Julien Grall wrote:
> On 27/09/2019 13:35, Julien Grall wrote:
> > Hi,
Hi Julien,


> > On 27/09/2019 12:57, Oleksandr Tyshchenko wrote:
> > > From: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
> > >
> > > There is a strict requirement for the IOMMU which wants to share
> > > the P2M table with the CPU. The IOMMU's Stage-2 input size must be 
> > > equal
> > > to the P2M IPA size. It is not a problem when the IOMMU can support
> > > all values the CPU supports. In that case, the IOMMU driver would just
> > > use any "p2m_ipa_bits" value as is. But, there are cases when not.
> > >
> > > In order to make P2M sharing possible on the platforms which
> > > IOMMUs have a limitation in maximum Stage-2 input size introduce
> > > the following logic.
> > >
> > > First initialize the IOMMU subsystem and gather requirements regarding
> > > the maximum IPA bits supported by each IOMMU device to figure out
> > > the minimum value among them. In the P2M code, take into the account
> > > the IOMMU requirements and choose suitable "pa_range" according
> > > to the restricted "p2m_ipa_bits".
> > >
> > > Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
> > > CC: Julien Grall <julien.grall@xxxxxxx>
> > Reviewed-by: Julien Grall <julien.grall@xxxxxxx>
> Committed now. Thank you!
Thank you!


I would like to remind regarding the last patch for this moment:

SUPPORT.md: Describe Renesas IPMMU-VMSA support (Arm)

https://lists.xenproject.org/archives/html/xen-devel/2019-09/msg02768.html


Thank you in advance.


--
Regards,

Oleksandr Tyshchenko


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