[PATCH net-next v2 00/15] ibmveth: Add multi-queue RX support

[Mingming Cao <mmc@linux.ibm.com>]

Hi,

Power11 PHYP firmware adds Virtual Ethernet multi-queue (MQ) RX for
the ibmveth device: multiple logical-LAN RX queues, per-queue buffer
posting, and completion delivery. Guest Linux did not use that
platform support; ibmveth still registered one RX queue even when
PHYP was MQ-capable.

This series adds the ibmveth MQ client. When PHYP advertises the
capability through H_ILLAN_ATTRIBUTES, the driver registers
multiple RX queues, receives on per-queue NAPI, and exposes queue
count through ethtool. Older firmware without the bit is unchanged.
Please apply to net-next.

Background
ibmveth today registers one logical LAN, one set of buffer pools, and
one NAPI context. PHYP MQ mode gives each RX queue its own handle:
buffers are posted with H_ADD_LOGICAL_LAN_BUFFERS_QUEUE, subordinate
queues register through H_REG_LOGICAL_LAN_QUEUE, and traffic can
land on any active queue. Queue selection is firmware-defined; v1
does not program RSS or hash tables. The driver needs per-queue
pools, IRQs, and poll state to match.

Queue-aware hcalls are selected only when probe sets multi_queue
from H_ILLAN_ATTRIBUTES; legacy firmware keeps the original hcall
path unchanged through the entire series.

This splits the work so review follows the actual bring-up sequence:
  1. Hypercall definitions and MQ data structures (patches 1-2)
  2. Refactor open/close into helpers - RX, per-queue pools,
     IRQ, TX, PHYP (3-9)
  3. Turn on the MQ datapath at probe/open (10)
  4. Per-queue RX/TX stats and sysfs pool readout (11-12)
  5. Runtime RX queue resize via ethtool -L (13-14)
  6. LPAR stability fix (15)

- Helper patches (3-9) reshape ibmveth_open()/close() into
queue-aware helpers. Runtime behaviour is unchanged through that
block: num_rx_queues stays 1 and multi_queue is false until patch 10.
- Patch 10 is the switch: probe sets multi_queue from firmware, raises
num_rx_queues, registers subordinates, and replenishes every active
queue.
- Patch 15 fixes poll hangs after aggressive ethtool -L cycling and
NAPI/close deadlocks on ip link down.

Testing
Tested on ppc64le PowerVM LPAR with MQ-capable firmware:
* Aggressive ethtool -L cycling (16/1/8/11/1/3/16/8/1) with ping
* MQ path: ethtool -L under iperf3 load, link down/up during traffic
* Legacy firmware (no MQ bit): full open/close/stress on the
  refactored helper path to confirm single-queue behaviour is
  unchanged

Changes in v2
v1 resubmit as 15 patches (Patchwork limit): same code and LPAR testing;
squashed split plus checkpatch fixes in patch 15 only.
v1: https://lore.kernel.org/r/cover.1782758799.git.mmc@linux.ibm.com
Patchwork: https://patchwork.kernel.org/project/netdevbpf/list/?series=1119106

Future work
* IRQ affinity hints for subordinate queue IRQs returned by PHYP
* Summed global no_buffer drop counter across all RX queues in MQ mode

Comments and suggestions on patch split, design, and testing are
welcome.

Mingming Cao <mmc@linux.ibm.com>

Mingming Cao (15):
  ibmveth: Refactor RX resource allocation for MQ RX bring-up
  ibmveth: Refactor buffer pool management for per-queue MQ RX
  ibmveth: Refactor RX interrupt control for MQ RX queues
  ibmveth: Refactor TX resource allocation in open/close paths
  ibmveth: Add RX queue register/deregister helpers for MQ
  ibmveth: Refactor open/close into MQ-ready resource pipeline
  ibmveth: Add queue-aware RX buffer submit helper for MQ
  ibmveth: Enable multi-queue RX receive path
  ibmveth: Add per-queue RX statistics collection and reporting
  ibmveth: Add per-queue TX statistics reporting
  ibmveth: Expose per-queue buffer pool details via sysfs
  ibmveth: Add helpers for incremental MQ RX queue resize
  ibmveth: Implement incremental MQ RX queue resize
  ibmveth: Wire ethtool set_channels to MQ RX queue resize
  ibmveth: Fix MQ RX poll and shutdown hangs after queue resize

 drivers/net/ethernet/ibm/ibmveth.c | 2350 +++++++++++++++++++++++-----
 drivers/net/ethernet/ibm/ibmveth.h |   25 +-
 2 files changed, 2014 insertions(+), 361 deletions(-)