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Message-ID: <aFJwt22XQkcZ4qQ4@soc-5CG4396X81.clients.intel.com>
Date: Wed, 18 Jun 2025 09:54:31 +0200
From: Larysa Zaremba <larysa.zaremba@...el.com>
To: "Tantilov, Emil S" <emil.s.tantilov@...el.com>
CC: <intel-wired-lan@...ts.osuosl.org>, Tony Nguyen
<anthony.l.nguyen@...el.com>, "David S. Miller" <davem@...emloft.net>, "Eric
Dumazet" <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
<pabeni@...hat.com>, Simon Horman <horms@...nel.org>, Jonathan Corbet
<corbet@....net>, Przemek Kitszel <przemyslaw.kitszel@...el.com>, Jiri Pirko
<jiri@...nulli.us>, Tatyana Nikolova <tatyana.e.nikolova@...el.com>, "Andrew
Lunn" <andrew+netdev@...n.ch>, Alexander Lobakin
<aleksander.lobakin@...el.com>, Michael Ellerman <mpe@...erman.id.au>,
"Maciej Fijalkowski" <maciej.fijalkowski@...el.com>, Lee Trager
<lee@...ger.us>, Madhavan Srinivasan <maddy@...ux.ibm.com>, Sridhar Samudrala
<sridhar.samudrala@...el.com>, Jacob Keller <jacob.e.keller@...el.com>,
Michal Swiatkowski <michal.swiatkowski@...ux.intel.com>, Mateusz Polchlopek
<mateusz.polchlopek@...el.com>, Ahmed Zaki <ahmed.zaki@...el.com>,
<netdev@...r.kernel.org>, <linux-doc@...r.kernel.org>,
<linux-kernel@...r.kernel.org>, "Karlsson, Magnus"
<magnus.karlsson@...el.com>, Madhu Chittim <madhu.chittim@...el.com>, "Josh
Hay" <joshua.a.hay@...el.com>, Milena Olech <milena.olech@...el.com>,
<pavan.kumar.linga@...el.com>, "Singhai, Anjali" <anjali.singhai@...el.com>,
Michal Kubiak <michal.kubiak@...el.com>
Subject: Re: [PATCH iwl-next v4 09/15] idpf: refactor idpf to use libie
control queues
On Tue, Jun 17, 2025 at 05:04:55PM -0700, Tantilov, Emil S wrote:
>
>
> On 5/16/2025 7:58 AM, Larysa Zaremba wrote:
> > From: Pavan Kumar Linga <pavan.kumar.linga@...el.com>
> >
> > Support to initialize and configure controlqs, and manage their
> > transactions was introduced in libie. As part of it, most of the existing
> > controlq structures are renamed and modified. Use those APIs in idpf and
> > make all the necessary changes.
> >
> > Previously for the send and receive virtchnl messages, there used to be a
> > memcpy involved in controlq code to copy the buffer info passed by the send
> > function into the controlq specific buffers. There was no restriction to
> > use automatic memory in that case. The new implementation in libie removed
> > copying of the send buffer info and introduced DMA mapping of the send
> > buffer itself. To accommodate it, use dynamic memory for the larger send
> > buffers. For smaller ones (<= 128 bytes) libie still can copy them into the
> > pre-allocated message memory.
> >
> > In case of receive, idpf receives a page pool buffer allocated by the libie
> > and care should be taken to release it after use in the idpf.
> >
> > The changes are fairly trivial and localized, with a notable exception
> > being the consolidation of idpf_vc_xn_shutdown and idpf_deinit_dflt_mbx
> > under the latter name. This has some additional consequences that are
> > addressed in the following patches.
>
> There is an issue with this approach that impacts the ability of the driver
> to force a reset. See below ...
>
> >
> > This refactoring introduces roughly additional 40KB of module storage used
> > for systems that only run idpf, so idpf + libie_cp + libie_pci takes about
> > 7% more storage than just idpf before refactoring.
> >
> > We now pre-allocate small TX buffers, so that does increase the memory
> > usage, but reduces the need to allocate. This results in additional 256 *
> > 128B of memory permanently used, increasing the worst-case memory usage by
> > 32KB but our ctlq RX buffers need to be of size 4096B anyway (not changed
> > by the patchset), so this is hardly noticeable.
> >
> > As for the timings, the fact that we are mostly limited by the HW response
> > time which is far from instant, is not changed by this refactor.
> >
> > Reviewed-by: Michal Kubiak <michal.kubiak@...el.com>
> > Signed-off-by: Pavan Kumar Linga <pavan.kumar.linga@...el.com>
> > Co-developed-by: Larysa Zaremba <larysa.zaremba@...el.com>
> > Signed-off-by: Larysa Zaremba <larysa.zaremba@...el.com>
> > ---
> > drivers/net/ethernet/intel/idpf/Kconfig | 2 +-
> > drivers/net/ethernet/intel/idpf/Makefile | 2 -
> > drivers/net/ethernet/intel/idpf/idpf.h | 27 +-
> > .../net/ethernet/intel/idpf/idpf_controlq.c | 624 -------
> > .../net/ethernet/intel/idpf/idpf_controlq.h | 130 --
> > .../ethernet/intel/idpf/idpf_controlq_api.h | 177 --
> > .../ethernet/intel/idpf/idpf_controlq_setup.c | 171 --
> > drivers/net/ethernet/intel/idpf/idpf_dev.c | 54 +-
> > .../net/ethernet/intel/idpf/idpf_ethtool.c | 37 +-
> > drivers/net/ethernet/intel/idpf/idpf_lib.c | 44 +-
> > drivers/net/ethernet/intel/idpf/idpf_main.c | 4 -
> > drivers/net/ethernet/intel/idpf/idpf_mem.h | 20 -
> > drivers/net/ethernet/intel/idpf/idpf_txrx.h | 2 +-
> > drivers/net/ethernet/intel/idpf/idpf_vf_dev.c | 60 +-
> > .../net/ethernet/intel/idpf/idpf_virtchnl.c | 1617 ++++++-----------
> > .../net/ethernet/intel/idpf/idpf_virtchnl.h | 90 +-
> > .../ethernet/intel/idpf/idpf_virtchnl_ptp.c | 204 +--
> > 17 files changed, 765 insertions(+), 2500 deletions(-)
> > delete mode 100644 drivers/net/ethernet/intel/idpf/idpf_controlq.c
> > delete mode 100644 drivers/net/ethernet/intel/idpf/idpf_controlq.h
> > delete mode 100644 drivers/net/ethernet/intel/idpf/idpf_controlq_api.h
> > delete mode 100644 drivers/net/ethernet/intel/idpf/idpf_controlq_setup.c
> > delete mode 100644 drivers/net/ethernet/intel/idpf/idpf_mem.h
> >
>
> <snip>
>
> > diff --git a/drivers/net/ethernet/intel/idpf/idpf_lib.c b/drivers/net/ethernet/intel/idpf/idpf_lib.c
> > index 68330b884967..500bff1091d9 100644
> > --- a/drivers/net/ethernet/intel/idpf/idpf_lib.c
> > +++ b/drivers/net/ethernet/intel/idpf/idpf_lib.c
> > @@ -1190,6 +1190,7 @@ void idpf_statistics_task(struct work_struct *work)
> > */
> > void idpf_mbx_task(struct work_struct *work)
> > {
> > + struct libie_ctlq_xn_recv_params xn_params = {};
> > struct idpf_adapter *adapter;
> > adapter = container_of(work, struct idpf_adapter, mbx_task.work);
> > @@ -1200,7 +1201,11 @@ void idpf_mbx_task(struct work_struct *work)
> > queue_delayed_work(adapter->mbx_wq, &adapter->mbx_task,
> > msecs_to_jiffies(300));
> > - idpf_recv_mb_msg(adapter, adapter->hw.arq);
> > + xn_params.xnm = adapter->xn_init_params.xnm;
> > + xn_params.ctlq = adapter->arq;
> > + xn_params.ctlq_msg_handler = idpf_recv_event_msg;
> > +
> > + libie_ctlq_xn_recv(&xn_params);
> > }
> > /**
> > @@ -1757,7 +1762,6 @@ static int idpf_init_hard_reset(struct idpf_adapter *adapter)
> > idpf_vc_core_deinit(adapter);
> > if (!is_reset)
>
> Since one of the checks in idpf_is_reset_detected() is !adapter->arq, this
> will never be possible through the event task. I think we may be able to
> remove this check altogether, but as-is this patch introduces large delays
> in the Tx hang recovery and depending on the cause may not recover at all.
>
> > reg_ops->trigger_reset(adapter, IDPF_HR_FUNC_RESET);
> > - idpf_deinit_dflt_mbx(adapter);
> > } else {
> > dev_err(dev, "Unhandled hard reset cause\n");
> > err = -EBADRQC;
> > @@ -1825,7 +1829,7 @@ void idpf_vc_event_task(struct work_struct *work)
> > return;
> > func_reset:
> > - idpf_vc_xn_shutdown(adapter->vcxn_mngr);
> > + idpf_deinit_dflt_mbx(adapter);
>
> This is not a straightforward swap, whereas previously we just discard
> messages knowing that we cannot communicate with the CP in a reset, this
> goes much further as it dismantles the MBX resources, and as a result the
> check `if (!is_reset)` in idpf_init_hard_reset() will never be true.
>
Thanks for finding this!
Given the problem seems to only relate to idpf_vc_event_task() in case of
IDPF_HR_FUNC_RESET and the following call sequence:
idpf_deinit_dflt_mbx(adapter);
set_bit(IDPF_HR_RESET_IN_PROG, adapter->flags);
idpf_init_hard_reset(adapter);
netif_carrier_off();
netif_tx_disable();
is_reset = idpf_is_reset_detected(adapter);
idpf_set_vport_state(adapter);
idpf_vc_core_deinit(adapter);
idpf_deinit_dflt_mbx(adapter);
...
...
I think, it is safe to remove idpf_deinit_dflt_mbx() from idpf_vc_event_task(),
given no mailbox communication is attempted in between it and
idpf_vc_core_deinit(). Anything going on in parallel also should not suffer from
having mailbox available just a little bit longer.
What do you think?
> <snip>
>
> Thanks,
> Emil
>
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