[PATCH for-next v2 0/2] RDMA/efa: Add AH cache for AH reuse

[Yonatan Nachum <ynachum@amazon.com>]

Changelog:
v2:
 * Zero-initialize AH cache key on cache lookup.
v1: https://lore.kernel.org/all/20260510083035.458081-1-ynachum@amazon.com/

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New EFA devices don't support the creation of multiple AHs to the same
remote on the same PD. To overcome this limitation, introduce an AH
cache that manages AH reuse transparently.

The cache uses an rhashtable keyed by (PD, GID) to track active address
handles with refcounts. On create AH, the driver returns an existing AH
number if one is already cached, or creates a new one and caches it. On
destroy AH, the driver only issues the device destroy command when the
last reference is dropped.

A per-entry mutex serializes concurrent device commands on the same
cache entry, preventing create-before-destroy races on the device.

Yonatan Nachum (2):
  RDMA/efa: Add initialization of AH cache rhashtable
  RDMA/efa: Add AH cache handling on create and destroy AH

 drivers/infiniband/hw/efa/Makefile       |   4 +-
 drivers/infiniband/hw/efa/efa_ah_cache.c | 154 +++++++++++++++++++++++
 drivers/infiniband/hw/efa/efa_ah_cache.h |  41 ++++++
 drivers/infiniband/hw/efa/efa_com.c      |  12 +-
 drivers/infiniband/hw/efa/efa_com.h      |   5 +-
 drivers/infiniband/hw/efa/efa_com_cmd.c  |  27 ++++
 drivers/infiniband/hw/efa/efa_com_cmd.h  |   1 +
 drivers/infiniband/hw/efa/efa_verbs.c    |   9 +-
 8 files changed, 245 insertions(+), 8 deletions(-)
 create mode 100644 drivers/infiniband/hw/efa/efa_ah_cache.c
 create mode 100644 drivers/infiniband/hw/efa/efa_ah_cache.h

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2.50.1