RE: [PATCH v2 1/1] iommu/vt-d: Fix missed device TLB cache tag

[Tian, Kevin]

> From: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> Sent: Thursday, June 20, 2024 2:30 PM
> 
> When a domain is attached to a device, the required cache tags are
> assigned to the domain so that the related caches can be flushed
> whenever it is needed. The device TLB cache tag is created based
> on whether the ats_enabled field of the device's iommu data is set.
> This creates an ordered dependency between cache tag assignment and
> ATS enabling.
> 
> The device TLB cache tag would not be created if device's ATS is
> enabled after the cache tag assignment. This causes devices with PCI
> ATS support to malfunction.
> 
> The ATS control is exclusively owned by the iommu driver. Hence, move
> cache_tag_assign_domain() after PCI ATS enabling to make sure that the
> device TLB cache tag is created for the domain.
> 
> Fixes: 3b1d9e2b2d68 ("iommu/vt-d: Add cache tag assignment interface")
> Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>

Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>