Re: [PATCH] iommu/amd: Enhance def_domain_type to handle untrusted device

[Vasant Hegde <vashegde@amd.com>]

Alex,


On 4/19/2024 8:54 PM, Deucher, Alexander wrote:
> [Public]
> 
>> -----Original Message-----
>> From: Hegde, Vasant <Vasant.Hegde@amd.com>
>> Sent: Friday, April 19, 2024 7:47 AM
>> To: iommu@lists.linux.dev; joro@8bytes.org
>> Cc: Suthikulpanit, Suravee <Suravee.Suthikulpanit@amd.com>; Deucher,
>> Alexander <Alexander.Deucher@amd.com>; Hegde, Vasant
>> <Vasant.Hegde@amd.com>; Eric Wagner <ewagner12@gmail.com>; Robin
>> Murphy <robin.murphy@arm.com>; Jason Gunthorpe <jgg@ziepe.ca>;
>> stable@kernel.org
>> Subject: [PATCH] iommu/amd: Enhance def_domain_type to handle
>> untrusted device
>>
>> Previously, IOMMU core layer was forcing IOMMU_DOMAIN_DMA domain
>> for untrusted device. This always took precedence over driver's
>> def_domain_type(). Commit 59ddce4418da ("iommu: Reorganize
>> iommu_get_default_domain_type() to respect def_domain_type()") changed
>> the behaviour. Current code calls def_domain_type() but if it doesn't return
>> IOMMU_DOMAIN_DMA for untrusted device it throws error. This results in
>> IOMMU group (and potentially IOMMU itself) in undetermined sstate.
>>
>> This patch adds untrusted check in AMD IOMMU driver code. So that it lets
>> eGPUs behind Thunderbolt work again.
>>
>> Fine tuning amd_iommu_def_domain_type() will be done later.
>>
>> Reported-by: Eric Wagner <ewagner12@gmail.com>
>> Link: https://lore.kernel.org/linux-iommu/CAHudX3zLH6CsRmLE-yb+gRjhh-
>> v4bU5_1jW_xCcxOo_oUUZKYg@mail.gmail.com
>> Fixes: 59ddce4418da ("iommu: Reorganize
>> iommu_get_default_domain_type() to respect def_domain_type()")
>> Cc: Robin Murphy <robin.murphy@arm.com>
>> Cc: Jason Gunthorpe <jgg@ziepe.ca>
>> Cc: stable@kernel.org # v6.7+
>> Signed-off-by: Vasant Hegde <vasant.hegde@amd.com>
> 
> Assuming it fixes the issue, please add:
> Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/3182

Sure. Will add it in v2.

-Vasant