Re: [Xen-devel] [PATCH v5] xen/iommu: smmu: Advertise when the SMMU support coherent table walk

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

On Mon, 2015-03-02 at 15:42 +0000, Julien Grall wrote:
> When SMMU doesn't support coherent table walk, Xen may need to clean
> updated PT (see commit 4c5f4cb "xen/arm: p2m: Clean cache PT when the
> IOMMU doesn't support coherent walk").
> 
> If one SMMU of the platform doesn't support coherent table walk, the
> feature is disabled for the whole platform. This is because device is
> assigned to a domain after the page table are populated.
> 
> This could impact performance on domain which doesn't use device
> passthrough. But, as the spec strongly recommends the support of this
> feature for mainstream platform, I expect server will always have SMMUs
> supporting coherent table walk. If not, we may need to enable this feature
> per-domain.
> 
> Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>

Acked + applied,thanks.



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