[PATCH v2 0/5] iommu/amd: Refactors for ATS robustness

[Pranjal Shrivastava <praan@google.com>]

This series forms the second half of the subsystem-wide ATS robustness
updates. The first part (focusing on the core subsystem, Intel, and ARM
SMMUv3) has already been merged upstream [1]. This half addresses the
AMD IOMMU driver and standardizes the PCI ATS API.

In v2, the series has been significantly restructured based on feedback
on v1. 

[v2]

 - Patch 1 Refctors the probe path, isolating capabilities into 
   iommu_init_device_caps().
 - Patch 2 renames iommu_ignore_device() to iommu_disable_device_dma().
   Following Jason's suggestion, it invalidates the hardware DTE by
   clearing the Valid bit (lower 128 bits) followed by the upper
   128 bits.  
 - Patch 3 splits the probe error paths to ensure that devices with
   config failures (like PD_MODE_NONE or ATS mismatches) can preserve
   their rlookup_table entries, successfully keeping IRQ remapping 
   functional for bypassed devices.
 - Patch 4 implements the "Fail Hard" pattern for ATS in the AMD driver,
   failing the probe and throwing a WARN_ON() upon ATS configuration or
   enablement failures.
 - Patch 5 enforces the checking of pci_ats_supported() prior to calling
   pci_prepare_ats() across the entire kernel PCI subsystem.

[v1]
 - https://lore.kernel.org/all/20260601134204.2150602-1-praan@google.com/

Thanks,
Praan

[1] https://lore.kernel.org/all/20260615235037.259909-1-praan@google.com/

Pranjal Shrivastava (5):
  iommu/amd: Refactor device probe and capability initialization
  iommu/amd: Fix DTE clearing and rename iommu_ignore_device()
  iommu/amd: Split probe error paths to preserve IRQ remapping
  iommu/amd: Fail probe on ATS configuration failure
  PCI/ATS: Mandate checking pci_ats_supported() before pci_prepare_ats()

 drivers/iommu/amd/iommu.c | 196 +++++++++++++++++++++++---------------
 drivers/pci/ats.c         |   6 +-
 2 files changed, 122 insertions(+), 80 deletions(-)

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2.55.0.691.gc56d675ccc-goog