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From:   Kai-Heng Feng <kai.heng.feng@canonical.com>
Date:   Thu, 27 Jan 2022 19:14:25 +0800
Message-ID: <CAAd53p6+KPAJchh9Jx59Fkkj5FidSxsW0yHjLqooFjvu-Y9u7w@mail.gmail.com>
Subject: Re: [PATCH v2 1/2] PCI/AER: Disable AER service when link is in L2/L3
 ready, L2 and L3 state
To:     Lu Baolu <baolu.lu@linux.intel.com>
Cc:     bhelgaas@google.com, mika.westerberg@linux.intel.com,
        koba.ko@canonical.com, Russell Currey <ruscur@russell.cc>,
        "Oliver O'Halloran" <oohall@gmail.com>,
        Lalithambika Krishnakumar <lalithambika.krishnakumar@intel.com>,
        Joerg Roedel <jroedel@suse.de>, linuxppc-dev@lists.ozlabs.org,
        linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org
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On Thu, Jan 27, 2022 at 3:01 PM Lu Baolu <baolu.lu@linux.intel.com> wrote:
>
> On 2022/1/27 10:54, Kai-Heng Feng wrote:
> > Commit 50310600ebda ("iommu/vt-d: Enable PCI ACS for platform opt in
> > hint") enables ACS, and some platforms lose its NVMe after resume from
> > S3:
> > [   50.947816] pcieport 0000:00:1b.0: DPC: containment event, status:0x1f01 source:0x0000
> > [   50.947817] pcieport 0000:00:1b.0: DPC: unmasked uncorrectable error detected
> > [   50.947829] pcieport 0000:00:1b.0: PCIe Bus Error: severity=Uncorrected (Non-Fatal), type=Transaction Layer, (Receiver ID)
> > [   50.947830] pcieport 0000:00:1b.0:   device [8086:06ac] error status/mask=00200000/00010000
> > [   50.947831] pcieport 0000:00:1b.0:    [21] ACSViol                (First)
> > [   50.947841] pcieport 0000:00:1b.0: AER: broadcast error_detected message
> > [   50.947843] nvme nvme0: frozen state error detected, reset controller
> >
> > It happens right after ACS gets enabled during resume.
> >
> > There's another case, when Thunderbolt reaches D3cold:
> > [   30.100211] pcieport 0000:00:1d.0: AER: Uncorrected (Non-Fatal) error received: 0000:00:1d.0
> > [   30.100251] pcieport 0000:00:1d.0: PCIe Bus Error: severity=Uncorrected (Non-Fatal), type=Transaction Layer, (Requester ID)
> > [   30.100256] pcieport 0000:00:1d.0:   device [8086:7ab0] error status/mask=00100000/00004000
> > [   30.100262] pcieport 0000:00:1d.0:    [20] UnsupReq               (First)
> > [   30.100267] pcieport 0000:00:1d.0: AER:   TLP Header: 34000000 08000052 00000000 00000000
> > [   30.100372] thunderbolt 0000:0a:00.0: AER: can't recover (no error_detected callback)
> > [   30.100401] xhci_hcd 0000:3e:00.0: AER: can't recover (no error_detected callback)
> > [   30.100427] pcieport 0000:00:1d.0: AER: device recovery failed
> >
> > So disable AER service to avoid the noises from turning power rails
> > on/off when the device is in low power states (D3hot and D3cold), as
> > PCIe spec "5.2 Link State Power Management" states that TLP and DLLP
> > transmission is disabled for a Link in L2/L3 Ready (D3hot), L2 (D3cold
> > with aux power) and L3 (D3cold).
> >
> > Bugzilla:https://bugzilla.kernel.org/show_bug.cgi?id=209149
> > Bugzilla:https://bugzilla.kernel.org/show_bug.cgi?id=215453
> > Fixes: 50310600ebda ("iommu/vt-d: Enable PCI ACS for platform opt in hint")
>
> I don't know what this fix has to do with the commit 50310600ebda.

Commit 50310600ebda only exposed the underlying issue. Do you think
"Fixes:" tag should change to other commits?

> Commit 50310600ebda only makes sure that PCI ACS is enabled whenever
> Intel IOMMU is on. Before this commit, PCI ACS could also be enabled
> and result in the same problem. Or anything I missed?

The system in question didn't enable ACS before commit 50310600ebda.

Kai-Heng

>
> Best regards,
> baolu