RE: [PATCH 1/1] iommu/vt-d: Disable PCI ATS in legacy passthrough mode

[Tian, Kevin]

> From: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> Sent: Tuesday, November 14, 2023 9:11 AM
> 
> When IOMMU hardware operates in legacy mode, the TT field of the context
> entry determines the translation type, with three supported types (Section
> 9.3 Context Entry):
> 
> - DMA translation without device TLB support
> - DMA translation with device TLB support
> - Passthrough mode with translated and translation requests blocked
> 
> Device TLB support is absent when hardware is configured in passthrough
> mode.
> 
> Disable the PCI ATS feature when IOMMU is configured for passthrough
> translation type in legacy (non-scalable) mode.
> 
> Fixes: 0faa19a1515f ("iommu/vt-d: Decouple PASID & PRI enabling from SVA")
> Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>

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