[PATCH net-next v3 0/2] Introduce auxiliary bus IRQs sysfs

Shay Drory
2024-05-08T04:05:27Z

Today, PCI PFs and VFs, which are anchored on the PCI bus, display their
IRQ information in the <pci_device>/msi_irqs/<irq_num> sysfs files.
PCI subfunctions (SFs) are similar to PFs and VFs and these SFs are
anchored on the auxiliary bus. However, these PCI SFs lack such IRQ
information on the auxiliary bus, leaving users without visibility into
which IRQs are used by the SFs. This absence makes it impossible to debug
situations and to understand the source of interrupts/SFs for performance
tuning and debug.

Additionally, the SFs are multifunctional devices supporting RDMA,
network devices, clocks, and more, similar to their peer PCI PFs and
VFs. Therefore, it is desirable to have SFs' IRQ information available
at the bus/device level.

To overcome the above limitations, this short series extends the auxiliary
bus to display IRQ information in sysfs, similar to that of PFs and VFs.

It adds an 'irqs' directory under the auxiliary device and includes an
<irq_num> sysfs file within it. Sometimes, the PCI SF auxiliary devices
share the IRQ with other SFs, a detail that is also not available to the
users. Consequently, this <irq_num> file indicates whether the IRQ is
'exclusive' or 'shared'.
This 'irqs' directory extenstion is optional, i.e. only for PCI SFs the
sysfs irq information is optionally exposed.

For example:
$ ls /sys/bus/auxiliary/devices/mlx5_core.sf.1/irqs/
50 51 52 53 54 55 56 57 58
$ cat /sys/bus/auxiliary/devices/mlx5_core.sf.1/irqs/52
exclusive

Patch summary:
==============
patch-1 adds auxiliary bus to support irqs used by auxiliary device
patch-2 mlx5 driver using exposing irqs for PCI SF devices via auxiliary
bus

---
v2->v3:
- addressed comments from Parav and Przemek in patch #1.
- fixed a bug in patch #2.
v1->v2:
- addressed comments from Greg, Simon H and kernel test boot in patch #1.

Shay Drory (2):
driver core: auxiliary bus: show auxiliary device IRQs
net/mlx5: Expose SFs IRQs

Documentation/ABI/testing/sysfs-bus-auxiliary | 14 ++
drivers/base/auxiliary.c | 170 +++++++++++++++++-
drivers/net/ethernet/mellanox/mlx5/core/eq.c | 6 +-
.../mellanox/mlx5/core/irq_affinity.c | 15 +-
.../ethernet/mellanox/mlx5/core/mlx5_core.h | 6 +
.../ethernet/mellanox/mlx5/core/mlx5_irq.h | 12 +-
.../net/ethernet/mellanox/mlx5/core/pci_irq.c | 12 +-
.../ethernet/mellanox/mlx5/core/sf/dev/dev.c | 2 +-
include/linux/auxiliary_bus.h | 15 +-
9 files changed, 237 insertions(+), 15 deletions(-)
create mode 100644 Documentation/ABI/testing/sysfs-bus-auxiliary

--
2.38.1