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

[Oleksandr Tyshchenko <olekstysh@xxxxxxxxx>]

Hi, Wei

On Fri, Jul 28, 2017 at 7:16 PM, Wei Liu <wei.liu2@xxxxxxxxxx> wrote:
> On Tue, Jul 25, 2017 at 08:26:51PM +0300, Oleksandr Tyshchenko wrote:
>> From: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
>>
>> 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@xxxxxxxx>
>> CC: Jan Beulich <jbeulich@xxxxxxxx>
>> CC: Julien Grall <julien.grall@xxxxxxx>
>> CC: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
>> CC: Wei Liu <wei.liu2@xxxxxxxxxx>
>>
>> ---
>>    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@xxxxxxxxxx>

Great. Thank you.

-- 
Regards,

Oleksandr Tyshchenko

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