From: Kai-Heng Feng <kai.heng.feng@canonical.com>
To: Bjorn Helgaas <helgaas@kernel.org>
Cc: Vinicius Costa Gomes <vinicius.gomes@intel.com>,
Tony Luck <tony.luck@intel.com>,
Kees Cook <keescook@chromium.org>,
linux-pci@vger.kernel.org, jesse.brandeburg@intel.com,
linux-kernel@vger.kernel.org,
"Guilherme G . Piccoli" <gpiccoli@igalia.com>,
Eric Dumazet <edumazet@google.com>,
netdev@vger.kernel.org, anthony.l.nguyen@intel.com,
linux-hardening@vger.kernel.org,
intel-wired-lan@lists.osuosl.org,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
"David S. Miller" <davem@davemloft.net>
Subject: Re: [Intel-wired-lan] [PATCH v2] igc: Ignore AER reset when device is suspended
Date: Mon, 17 Jul 2023 15:47:04 +0800 [thread overview]
Message-ID: <CAAd53p6SiQrmjWA3=4CE0tw15-ZfmkcqTNoheXzkkkargfGtCw@mail.gmail.com> (raw)
In-Reply-To: <20230715191216.GA364070@bhelgaas>
On Sun, Jul 16, 2023 at 3:12 AM Bjorn Helgaas <helgaas@kernel.org> wrote:
>
> On Fri, Jul 14, 2023 at 01:35:55PM -0700, Vinicius Costa Gomes wrote:
> > Bjorn Helgaas <helgaas@kernel.org> writes:
> > > On Fri, Jul 14, 2023 at 01:05:41PM +0800, Kai-Heng Feng wrote:
> > >> When a system that connects to a Thunderbolt dock equipped with I225,
> > >> like HP Thunderbolt Dock G4, I225 stops working after S3 resume:
> > >> ...
> > >
> > >> The issue is that the PTM requests are sending before driver resumes the
> > >> device. Since the issue can also be observed on Windows, it's quite
> > >> likely a firmware/hardware limitation.
> > >
> > > Does this mean we didn't disable PTM correctly on suspend? Or is the
> > > device defective and sending PTM requests even though PTM is disabled?
> >
> > The way I understand the hardware bug, the device is defective, as you
> > said, the device sends PTM messages when "busmastering" is disabled.
>
> Bus Master Enable controls the ability of a Function to issue Memory
> and I/O Read/Write Requests (PCIe r6.0, sec 7.5.1.1.3). PTM uses
> Messages, and I don't think they should be affected by Bus Master
> Enable.
>
> I also don't understand the I225 connection. We have these
> Uncorrected Non-Fatal errors:
>
> > >> [ 606.527931] pcieport 0000:00:1d.0: AER: Multiple Uncorrected (Non-Fatal) error received: 0000:00:1d.0
> > >> [ 606.528064] pcieport 0000:00:1d.0: PCIe Bus Error: severity=Uncorrected (Non-Fatal), type=Transaction Layer, (Requester ID)
> > >> [ 606.528068] pcieport 0000:00:1d.0: device [8086:7ab0] error status/mask=00100000/00004000
> > >> [ 606.528072] pcieport 0000:00:1d.0: [20] UnsupReq (First)
> > >> [ 606.528075] pcieport 0000:00:1d.0: AER: TLP Header: 34000000 0a000052 00000000 00000000
> > >> [ 606.528079] pcieport 0000:00:1d.0: AER: Error of this Agent is reported first
> > >> [ 606.528098] pcieport 0000:04:01.0: PCIe Bus Error: severity=Uncorrected (Non-Fatal), type=Transaction Layer, (Requester ID)
> > >> [ 606.528101] pcieport 0000:04:01.0: device [8086:1136] error status/mask=00300000/00000000
> > >> [ 606.528105] pcieport 0000:04:01.0: [20] UnsupReq (First)
> > >> [ 606.528107] pcieport 0000:04:01.0: [21] ACSViol
> > >> [ 606.528110] pcieport 0000:04:01.0: AER: TLP Header: 34000000 04000052 00000000 00000000
>
> They are clearly Unsupported Request errors caused by PTM Requests
> (decoding at https://bugzilla.kernel.org/show_bug.cgi?id=216850#c9),
> but they were logged by 00:1d.0 and 04:01.0.
>
> The hierarchy is this:
>
> 00:1d.0 Root Port to [bus 03-6c]
> 03:00.0 Switch Upstream Port to [bus 04-6c]
> 04:01.0 Switch Downstream Port to [bus 06-38]
> 06:00.0 Switch Upstream Port to [bus 07-38]
> 07:04.0 Switch Downstream Port to [bus 38]
> 38:00.0 igc I225 NIC
>
> If I225 sent a PTM request when it shouldn't have, i.e., when 07:04.0
> didn't have PTM enabled, the error would have been logged by 07:04.0.
>
> The fact that the errors were logged by 00:1d.0 and 04:01.0 means that
> they were caused by PTM requests from 03:00.0 and 06:00.0.
OK, so the PTM is actually fired by the Thunderbolt switch.
That means the I225 reset is collateral damage.
Let me see if I can reproduce the UR PTM with other devices.
Kai-Heng
>
> Bjorn
next prev parent reply other threads:[~2023-07-17 7:47 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-14 5:05 [PATCH v2] igc: Ignore AER reset when device is suspended Kai-Heng Feng
2023-07-14 14:54 ` Bjorn Helgaas
2023-07-14 20:35 ` Vinicius Costa Gomes
2023-07-15 19:12 ` [Intel-wired-lan] " Bjorn Helgaas
2023-07-17 7:47 ` Kai-Heng Feng [this message]
2023-07-17 7:38 ` Kai-Heng Feng
2023-07-17 22:42 ` [Intel-wired-lan] " Bjorn Helgaas
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