Subject: [PATCH 0/3] powerpc: Cleanup and convert to MSI parent domain

From: Nam Cao <[email-masked]>
Date: Thu, 26 Jun 2025 16:47:39 +0200

The initial implementation of PCI/MSI interrupt domains in the hierarchical
interrupt domain model used a shortcut by providing a global PCI/MSI
domain.

This works because the PCI/MSI[X] hardware is standardized and uniform, but
it violates the basic design principle of hierarchical interrupt domains:
Each hardware block involved in the interrupt delivery chain should have a
separate interrupt domain.

For PCI/MSI[X], the interrupt controller is per PCI device and not a global
made-up entity.

Unsurprisingly, the shortcut turned out to have downsides as it does not
allow dynamic allocation of interrupt vectors after initialization and it
prevents supporting IMS on PCI. For further details, see:

https://lore.kernel.org/lkml/[email-masked]/

The solution is implementing per device MSI domains, this means the
entities which provide global PCI/MSI domain so far have to implement MSI
parent domain functionality instead.

This series:

   - Untangle XIVE driver from Powernv and Pseries drivers

   - Convert the Powernv and Pseries drivers to implement MSI parent domain
     functionality

Nam Cao (3):
  powerpc/xive: Untangle xive from child interrupt controller drivers
  powerpc/powernv/pci: Switch to use msi_create_parent_irq_domain()
  powerpc/pseries/msi: Switch to msi_create_parent_irq_domain()

 arch/powerpc/include/asm/pci-bridge.h     |   2 -
 arch/powerpc/include/asm/xive.h           |   1 -
 arch/powerpc/platforms/powernv/Kconfig    |   1 +
 arch/powerpc/platforms/powernv/pci-ioda.c |  96 ++++++-----------
 arch/powerpc/platforms/pseries/Kconfig    |   1 +
 arch/powerpc/platforms/pseries/msi.c      | 124 ++++++++--------------
 arch/powerpc/sysdev/xive/common.c         |  63 ++++++-----
 7 files changed, 113 insertions(+), 175 deletions(-)

-- 
2.39.5