[bugzilla-daemon@bugzilla.kernel.org: [Bug 209149] New: "iommu/vt-d: Enable PCI ACS for platform opt in hint" makes NVMe config space not accessible after S3]

[Bjorn Helgaas <helgaas@kernel.org>]

[+cc IOMMU and NVMe folks]

Sorry, I forgot to forward this to linux-pci when it was first
reported.

Apparently this happens with v5.9-rc3, and may be related to
50310600ebda ("iommu/vt-d: Enable PCI ACS for platform opt in hint"),
which appeared in v5.8-rc3.

There are several dmesg logs and proposed patches in the bugzilla, but
no analysis yet of what the problem is.  From the first dmesg
attachment (https://bugzilla.kernel.org/attachment.cgi?id=292327):

  [   50.434945] PM: suspend entry (deep)
  [   50.802086] nvme 0000:01:00.0: saving config space at offset 0x0 (reading 0x11e0f)
  [   50.842775] ACPI: Preparing to enter system sleep state S3
  [   50.858922] ACPI: Waking up from system sleep state S3
  [   50.883622] nvme 0000:01:00.0: can't change power state from D3hot to D0 (config space inaccessible)
  [   50.947352] nvme 0000:01:00.0: restoring config space at offset 0x0 (was 0xffffffff, writing 0x11e0f)
  [   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

I suspect the nvme "can't change power state" and restore config space
errors are a consequence of the DPC event.  If DPC disables the link,
the device is inaccessible.

I don't know what caused the ACS Violation.  The AER TLP Header Log
might have a clue, but unfortunately we didn't print it.

Tangent:

  The fact that we didn't print the AER TLP Header log looks like
  a bug in itself.  PCIe r5.0, sec 6.2.7, table 6-5, says many
  errors, including ACS Violation, should log the TLP header.  But
  aer_get_device_error_info() only reads the log for error bits in
  AER_LOG_TLP_MASKS, which doesn't include PCI_ERR_UNC_ACSV.

  I don't think there's a "TLP Header Log Valid" bit, and it's ugly to
  have to update AER_LOG_TLP_MASKS if new errors are added.  I think
  maybe we should always print the header log.

----- Forwarded message from bugzilla-daemon@bugzilla.kernel.org -----

Date: Fri, 04 Sep 2020 14:31:20 +0000
From: bugzilla-daemon@bugzilla.kernel.org
To: bjorn@helgaas.com
Subject: [Bug 209149] New: "iommu/vt-d: Enable PCI ACS for platform opt in
	hint" makes NVMe config space not accessible after S3
Message-ID: <bug-209149-41252@https.bugzilla.kernel.org/>

https://bugzilla.kernel.org/show_bug.cgi?id=209149

            Bug ID: 209149
           Summary: "iommu/vt-d: Enable PCI ACS for platform opt in hint"
                    makes NVMe config space not accessible after S3
           Product: Drivers
           Version: 2.5
    Kernel Version: mainline
          Hardware: All
                OS: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: PCI
          Assignee: drivers_pci@kernel-bugs.osdl.org
          Reporter: kai.heng.feng@canonical.com
        Regression: No

Here's the error:
[   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

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