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Re: [Xen-devel] Unshared IOMMU issues



On 21/02/17 10:39, Oleksandr Tyshchenko wrote:
Hi, Julien.

Hi Oleksandr,

On Mon, Feb 20, 2017 at 10:31 AM, Julien Grall <julien.grall@xxxxxxx> wrote:
Hello Oleksandr,

On 02/17/2017 08:20 PM, Oleksandr Tyshchenko wrote:

Hi, all.

So, as I understand we have two possible solutions for the IOMMU page
table to be populated:
1.  When the first device is being assigned. Retrieve all mappings
from stage-2 table.
2.  When the domain is being created.

I would prefer the second variant.


I am happy with the second variant as long as IOMMU is not enabled by
default when the guest will have no device assigned.
OK.

Just to clarify.
We don't need to assign devices when creating domain (at the
iommu_domain_init() time).
We just need to have some knowledge about device assignment in general
(will the guest have assigned devices or won't) .
And only in case when the guest is going to have assigned devices we
will populate IOMMU page table (call iommu_construct()).
Right?

That's correct.

Cheers,

--
Julien Grall

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