netdev - [PATCH net-next v5 0/4] virtio-net: Link queues to NAPIs

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Message-ID: <20250227185017.206785-1-jdamato@fastly.com>
Date: Thu, 27 Feb 2025 18:50:10 +0000
From: Joe Damato <jdamato@...tly.com>
To: netdev@...r.kernel.org
Cc: mkarsten@...terloo.ca,
	gerhard@...leder-embedded.com,
	jasowang@...hat.com,
	xuanzhuo@...ux.alibaba.com,
	kuba@...nel.org,
	mst@...hat.com,
	leiyang@...hat.com,
	Joe Damato <jdamato@...tly.com>,
	Alexei Starovoitov <ast@...nel.org>,
	Andrew Lunn <andrew+netdev@...n.ch>,
	bpf@...r.kernel.org (open list:XDP (eXpress Data Path):Keyword:(?:\b|_)xdp(?:\b|_)),
	Daniel Borkmann <daniel@...earbox.net>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Eugenio Pérez <eperezma@...hat.com>,
	Jesper Dangaard Brouer <hawk@...nel.org>,
	John Fastabend <john.fastabend@...il.com>,
	linux-kernel@...r.kernel.org (open list),
	Paolo Abeni <pabeni@...hat.com>,
	virtualization@...ts.linux.dev (open list:VIRTIO CORE AND NET DRIVERS)
Subject: [PATCH net-next v5 0/4] virtio-net: Link queues to NAPIs

Greetings:

Welcome to v5. Patches 1, 2, and 4 have no functional changes only
updated tags. Patch 3 was refactored as requested by Jason. See the
changelog below and the commit message for details.

Jakub recently commented [1] that I should not hold this series on
virtio-net linking queues to NAPIs behind other important work that is
on-going and suggested I re-spin, so here we are :)

As per the discussion on the v3 [2], now both RX and TX NAPIs use the
API to link queues to NAPIs. Since TX-only NAPIs don't have a NAPI ID,
commit 6597e8d35851 ("netdev-genl: Elide napi_id when not present") now
correctly elides the TX-only NAPIs (instead of printing zero) when the
queues and NAPIs are linked.

As per the discussion on the v4 [3], patch 3 has been refactored to hold
RTNL only in the specific locations which need it as Jason requested.

See the commit message of patch 3 for an example of how to get the NAPI
to queue mapping information.

See the commit message of patch 4 for an example of how NAPI IDs are
persistent despite queue count changes.

Thanks,
Joe

[1]: https://lore.kernel.org/netdev/20250221142650.3c74dcac@kernel.org/
[2]: https://lore.kernel.org/netdev/20250127142400.24eca319@kernel.org/
[3]: https://lore.kernel.org/netdev/CACGkMEv=ejJnOWDnAu7eULLvrqXjkMkTL4cbi-uCTUhCpKN_GA@mail.gmail.com/

v5:
  - Patch 1 added Acked-by's from Michael and Jason. Added Tested-by
    from Lei. No functional changes.
  - Patch 2 added Acked-by's from Michael and Jason. Added Tested-by
    from Lei. No functional changes.
  - Patch 3:
    - Refactored as Jason requested, eliminating the
      virtnet_queue_set_napi helper entirely, and explicitly holding
      RTNL in the 3 locations where needed (refill_work, freeze, and
      restore).
    - Commit message updated to outline the known paths at the time the
      commit was written.
  - Patch 4 added Acked-by from Michael. Added Tested-by from Lei. No
    functional changes.

v4: https://lore.kernel.org/lkml/20250225020455.212895-1-jdamato@fastly.com/
  - Dropped Jakub's patch (previously patch 1).
  - Significant refactor from v3 affecting patches 1-3.
  - Patch 4 added tags from Jason and Gerhard.

rfcv3: https://lore.kernel.org/netdev/20250121191047.269844-1-jdamato@fastly.com/
  - patch 3:
    - Removed the xdp checks completely, as Gerhard Engleder pointed
      out, they are likely not necessary.

  - patch 4:
    - Added Xuan Zhuo's Reviewed-by.

v2: https://lore.kernel.org/netdev/20250116055302.14308-1-jdamato@fastly.com/
  - patch 1:
    - New in the v2 from Jakub.

  - patch 2:
    - Previously patch 1, unchanged from v1.
    - Added Gerhard Engleder's Reviewed-by.
    - Added Lei Yang's Tested-by.

  - patch 3:
    - Introduced virtnet_napi_disable to eliminate duplicated code
      in virtnet_xdp_set, virtnet_rx_pause, virtnet_disable_queue_pair,
      refill_work as suggested by Jason Wang.
    - As a result of the above refactor, dropped Reviewed-by and
      Tested-by from patch 3.

  - patch 4:
    - New in v2. Adds persistent NAPI configuration. See commit message
      for more details.

v1: https://lore.kernel.org/netdev/20250110202605.429475-1-jdamato@fastly.com/

Joe Damato (4):
  virtio-net: Refactor napi_enable paths
  virtio-net: Refactor napi_disable paths
  virtio-net: Map NAPIs to queues
  virtio_net: Use persistent NAPI config

 drivers/net/virtio_net.c | 95 ++++++++++++++++++++++++++++------------
 1 file changed, 67 insertions(+), 28 deletions(-)


base-commit: 7fe0353606d77a32c4c7f2814833dd1c043ebdd2
-- 
2.45.2