Hi, Julien, Roger.
On Thu, Aug 08, 2019 at 01:53:23PM +0300, Oleksandr Tyshchenko wrote:
From: Oleksandr Tyshchenko <[email protected]>
Don't skip IOMMU nodes when creating DT for Dom0 if IOMMU has been
forcibly disabled in bootargs (e.g. "iommu=0") in order to let
the IOMMU be accessible by DOM0.
I don't think your code is doing what you expect... If iommu=0, then
Xen will not lookup for IOMMUs (iommu_hardware_setup() will not be
called). So none of the device will have DEVICE_IOMMU set and hence
they are already given to dom0.
But I think it is wrong to give the IOMMUs to Dom0 when iommu=0. This
is not the goal of this option. If you want to passthrough the IOMMU
to Dom0, then you should use the parameter iommu_hwdom_passthrough.
However, I agree with Roger that giving the IOMMU to dom0 is a pretty
bad idea. So this should be fixed.
I fully agree with the arguments provided that it is a bad idea. So,
please consider that patch as not relevant.
But, I am not sure I follow the last sentence:
>>> If iommu=0, then Xen will not lookup for IOMMUs
(iommu_hardware_setup() will not be called). So none of the device will
have DEVICE_IOMMU set and hence they are already given to dom0.
I can see that devices have DEVICE_IOMMU set. Although, the IOMMU driver
is not in use, it is present and compatible matches. So, even if
iommu=0, the IOMMU devices are not given to Dom0, because of skipped. Or
I missed something?
--
Regards,
Oleksandr Tyshchenko
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