[PATCH] pci/shpchp: no claim on pcie port device

[Pingfan Liu]

On Tue, Jun 12, 2018 at 2:42 PM Pingfan Liu <kernelfans at gmail.com> wrote:
>
> The Linux Device Driver Model allows a physical device to be handled
> by only a single driver. But at present, both shpchp and portdrv_pci
> claim PCI_CLASS_BRIDGE_PCI, and touch devices_kset. This causes a
> few problems, one is the wrong shutdown seq of devices, owing to the
> broken devices_kset.
>
> I hit this bug on a Power9 machine, when "kexec -e", and see a ata-disk
> behind a bridge can not write back buffer in flight due to the former
> shutdown of the bridge which clears the BusMaster bit.
>
> Note the device involved:
> 0004:00:00.0 PCI bridge: IBM Device 04c1 (prog-if 00 [Normal decode])
>         Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR+ FastB2B- DisINTx-
>         Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
>         Latency: 0
>         NUMA node: 0
>         Bus: primary=00, secondary=01, subordinate=12, sec-latency=0
>         I/O behind bridge: 00000000-00000fff
>         Memory behind bridge: 80000000-ffefffff
>         Prefetchable memory behind bridge: 0006024000000000-0006027f7fffffff
>         Secondary status: 66MHz- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- <SERR- <PERR-
>         BridgeCtl: Parity- SERR+ NoISA- VGA- MAbort- >Reset- FastB2B-
>                 PriDiscTmr- SecDiscTmr- DiscTmrStat- DiscTmrSERREn-
>         Capabilities: [40] Power Management version 3
>                 Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA PME(D0+,D1-,D2-,D3hot+,D3cold+)
>                 Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-
>         Capabilities: [48] Express (v2) Root Port (Slot-), MSI 00
>                 DevCap: MaxPayload 512 bytes, PhantFunc 0
>                         ExtTag- RBE+
>                 DevCtl: Report errors: Correctable- Non-Fatal- Fatal- Unsupported-
>                         RlxdOrd- ExtTag- PhantFunc- AuxPwr- NoSnoop-
>                         MaxPayload 256 bytes, MaxReadReq 128 bytes
>                 DevSta: CorrErr- UncorrErr- FatalErr- UnsuppReq- AuxPwr- TransPend-
>                 LnkCap: Port #0, Speed 8GT/s, Width x8, ASPM not supported, Exit Latency L0s <64ns, L1 <1us
>                         ClockPM- Surprise- LLActRep+ BwNot+ ASPMOptComp-
>                 LnkCtl: ASPM Disabled; RCB 128 bytes Disabled- CommClk-
>                         ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt-
>                 LnkSta: Speed 8GT/s, Width x4, TrErr- Train- SlotClk- DLActive+ BWMgmt- ABWMgmt+
>                 RootCtl: ErrCorrectable- ErrNon-Fatal- ErrFatal- PMEIntEna- CRSVisible-
>                 RootCap: CRSVisible-
>                 RootSta: PME ReqID 0000, PMEStatus- PMEPending-
>                 DevCap2: Completion Timeout: Range ABCD, TimeoutDis+, LTR-, OBFF Not Supported ARIFwd+
>                 DevCtl2: Completion Timeout: 16ms to 55ms, TimeoutDis+, LTR-, OBFF Disabled ARIFwd+
>                 LnkCtl2: Target Link Speed: 8GT/s, EnterCompliance- SpeedDis-
>                          Transmit Margin: Normal Operating Range, EnterModifiedCompliance- ComplianceSOS-
>                          Compliance De-emphasis: -6dB
>                 LnkSta2: Current De-emphasis Level: -3.5dB, EqualizationComplete+, EqualizationPhase1+
>                          EqualizationPhase2+, EqualizationPhase3+, LinkEqualizationRequest-
>         Capabilities: [100 v1] Advanced Error Reporting
>                 UESta:  DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
>                 UEMsk:  DLP- SDES- TLP+ FCP- CmpltTO+ CmpltAbrt+ UnxCmplt- RxOF- MalfTLP- ECRC+ UnsupReq- ACSViol-
>                 UESvrt: DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
>                 CESta:  RxErr- BadTLP- BadDLLP- Rollover- Timeout- NonFatalErr-
>                 CEMsk:  RxErr- BadTLP- BadDLLP- Rollover- Timeout- NonFatalErr-
>                 AERCap: First Error Pointer: 00, GenCap+ CGenEn+ ChkCap+ ChkEn+
>         Capabilities: [148 v1] #19
>
> Signed-off-by: Pingfan Liu <kernelfans at gmail.com>
> ---
>  drivers/pci/hotplug/shpchp_core.c | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/drivers/pci/hotplug/shpchp_core.c b/drivers/pci/hotplug/shpchp_core.c
> index 1f0f969..2cd8e19 100644
> --- a/drivers/pci/hotplug/shpchp_core.c
> +++ b/drivers/pci/hotplug/shpchp_core.c
> @@ -287,6 +287,13 @@ static int shpc_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
>         int rc;
>         struct controller *ctrl;
>
> +       /* do not claim pcie port device */
> +       if (pci_is_pcie(dev) &&
> +           ((pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT) ||
> +            (pci_pcie_type(dev) == PCI_EXP_TYPE_UPSTREAM) ||
> +            (pci_pcie_type(dev) == PCI_EXP_TYPE_DOWNSTREAM)))
> +               return -ENODEV;
> +
Sorry, should s/dev/pdev/.  I will try to loan a power9 to test it.
NACK it, I will send out v2.

Thanks,
Pingfan
>         if (!is_shpc_capable(pdev))
>                 return -ENODEV;
>
> --
> 2.7.4
>