Re: [PATCH v2 09/13] xen/arm: Add use_iommu flag to xen_arch_domainconfig

[Wei Liu <wei.liu2@citrix.com>]

On Tue, Jul 25, 2017 at 08:26:51PM +0300, Oleksandr Tyshchenko wrote:
> From: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
> 
> This flag is intended to let Xen know that the guest has devices
> which will most likely be used for passthrough and as the result
> the IOMMU is expected to be used for this domain.
> 
> The primary aim of this knowledge is to help the IOMMUs that don't
> share page tables with the CPU on ARM be ready before P2M code starts
> updating IOMMU mapping.
> So, if this flag is set the non-shared IOMMUs will populate
> their page tables at the domain creation time and thereby will be able
> to handle IOMMU mapping updates from *the very beginning*.
> 
> In order to retain the current behavior for x86 still call
> iommu_domain_init() with use_iommu flag being forced to false.
> 
> Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
> CC: Jan Beulich <jbeulich@suse.com>
> CC: Julien Grall <julien.grall@arm.com>
> CC: Ian Jackson <ian.jackson@eu.citrix.com>
> CC: Wei Liu <wei.liu2@citrix.com>
> 
> ---
>    Changes in V1:
>       - Treat use_iommu flag as the ARM decision only. Don't use
>         common domain creation flag for it, use ARM config instead.
>       - Clarify patch subject/description.
> 
>    Changes in V2:
>       - Cosmetic fixes.
> ---
>  tools/libxl/libxl_arm.c       | 8 ++++++++

Acked-by: Wei Liu <wei.liu2@citrix.com>

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