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From:   Kai-Heng Feng <kai.heng.feng@canonical.com>
Date:   Fri, 28 Jan 2022 11:29:54 +0800
Message-ID: <CAAd53p5rNFBK8t7bK_Jdds2c4dXpWtEb10iTtsc4zQEjGrf-Pg@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 Fri, Jan 28, 2022 at 10:57 AM Lu Baolu <baolu.lu@linux.intel.com> wrote:
>
> On 1/27/22 7:14 PM, Kai-Heng Feng wrote:
> > 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.
>
> This commit exposed the issue on your configuration doesn't mean the
> fix should be back ported as far as that commit. I believe if you add
> intel-iommu=on in the kernel parameter, the issue still exists even you
> revert commit 50310600ebda or checkout a tag before it.

That's true.

I guess it's better to drop the "Fixes:" tag.

Bjorn, should I send another version of it?

Kai-Heng

>
> Best regards,
> baolu