PCI: xgene-msi: Sanitise MSI allocation and affinity setting

Plugging a device that doesn't use managed affinity on an XGene-1
machine results in messages such as:

  genirq: irq_chip PCI-MSIX-0000:01:00.0 did not update eff. affinity mask of irq 39

As it turns out, the driver was never updated to populate the effective
affinity on irq_set_affinity() call, and the core code is prickly about
that.

But upon further investigation, it appears that the driver keeps repainting
the hwirq field of the irq_data structure as a way to track the affinity
of the MSI, something that is very much frowned upon as it breaks the
fundamentals of an IRQ domain (an array indexed by hwirq).

Fixing this results more or less in a rewrite of the driver:

- Define how a hwirq and a CPU affinity map onto the MSI termination
  registers

- Allocate a single entry in the bitmap per MSI instead of *8*

- Correctly track CPU affinity

- Fix the documentation so that it actually means something (to me)

- Use standard bitmap iterators

- and plenty of other cleanups

With this, the driver behaves correctly on my vintage Mustang board.

Signed-off-by: Marc Zyngier <maz@kernel.org>
[lpieralisi: replaced open coded GENMASK(6, 4) with MSInRx_HWIRQ_MASK]
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://lore.kernel.org/r/20250708173404.1278635-10-maz@kernel.org

0 files changed, 0 insertions, 0 deletions