Message-ID: <3C6A30BC-5826-4BD8-BF93-BE964FECAA4A@intel.com>
Date:   Wed, 05 Aug 2020 11:12:20 -0700
From:   "Sean V Kelley" <sean.v.kelley@...el.com>
To:     "Bjorn Helgaas" <helgaas@...nel.org>
Cc:     bhelgaas@...gle.com, Jonathan.Cameron@...wei.com,
        rjw@...ysocki.net, ashok.raj@...el.com, tony.luck@...el.com,
        sathyanarayanan.kuppuswamy@...ux.intel.com,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2 0/9] Add RCEC handling to PCI/AER

On 5 Aug 2020, at 11:00, Bjorn Helgaas wrote:

> On Tue, Aug 04, 2020 at 12:40:43PM -0700, Sean V Kelley wrote:
>> From: Sean V Kelley <sean.v.kelley@...ux.intel.com>
>>
>> On the use of FLR on RCiEPs for the fatal case, still interested in 
>> more
>> feedback from the earlier discussion here [1]:
>>
>> [1] 
>> https://lore.kernel.org/linux-pci/C21C050B-48B1-4429-B019-C81F3AB8E843@intel.com/
>>
>> There is also the question of the absence of an FLR for non-fatal 
>> error.
>> If the device driver tells us that it needs 
>> "PCI_ERS_RESULT_NEED_RESET" by
>> the callback report_normal_detected() then we should try FLR on the 
>> device
>> as well.
>>
>> On the use of variables with RP centric names such as the attributes
>> dev_attr_aer_rootport_total_err_..., one concern is the ripple effect 
>> on code
>> churn due to renaming. Open to suggestions, but trying to co-habitate 
>> so to
>> speak RCECs with RPs in the same drivers has trade-offs.
>>
>> Changes since v1 [2]:
>>
>> - Make PME capability of RCEC discoverable in 
>> get_port_device_capability().
>> - Replace the check on bnr with <= lastbusn in pcie_walk_rcec().
>> - Fix comment header for pcie_walk_rcec().
>> - Fix comment header for pci_walk_dev_affected().
>> - Fix spurious newline.
>> - Add sanity checks on dev->rcec.
>> - Use pci_dbg() in place of pci_info() for discovered RCiEPs.
>> - Remove AER RCEC AP FOUND message (accidently left in previously).
>> - Remove the check for RC_END from set_device_error_reporting() since
>> only Ports and RCECs are being passed.
>> (Jonathan Cameron)
>> - Fix the return type for flr_on_rciep().
>> (reported by lkp on DEC Alpha arch.)
>>
>> [1] 
>> https://lore.kernel.org/linux-pci/20200724172223.145608-1-sean.v.kelley@intel.com/
>>
>> Root Complex Event Collectors (RCEC) provide support for terminating 
>> error
>> and PME messages from Root Complex Integrated Endpoints (RCiEPs).  An 
>> RCEC
>> resides on a Bus in the Root Complex. Multiple RCECs can in fact 
>> reside on
>> a single bus. An RCEC will explicitly declare supported RCiEPs 
>> through the
>> Root Complex Endpoint Association Extended Capability.
>>
>> (See PCIe 5.0-1, sections 1.3.2.3 (RCiEP), and 7.9.10 (RCEC Ext. 
>> Cap.))
>>
>> The kernel lacks handling for these RCECs and the error messages 
>> received
>> from their respective associated RCiEPs. More recently, a new CPU
>> interconnect, Compute eXpress Link (CXL) depends on RCEC capabilities 
>> for
>> purposes of error messaging from CXL 1.1 supported RCiEP devices.
>>
>> DocLink: https://www.computeexpresslink.org/
>>
>> This use case is not limited to CXL. Existing hardware today includes
>> support for RCECs, such as the Denverton microserver product
>> family. Future hardware will be forthcoming.
>>
>> (See Intel Document, Order number: 33061-003US)
>>
>> So services such as AER or PME could be associated with an RCEC 
>> driver.
>> In the case of CXL, if an RCiEP (i.e., CXL 1.1 device) is associated 
>> with a
>> platform's RCEC it shall signal PME and AER error conditions through 
>> that
>> RCEC.
>>
>> Towards the above use cases, add the missing RCEC class and extend 
>> the
>> PCIe Root Port and service drivers to allow association of RCiEPs to 
>> their
>> respective parent RCEC and facilitate handling of terminating error 
>> and PME
>> messages.
>>
>>
>> AER Test Results:
>> 1) Inject a correctable error to the RCiEP 0000:e9:00.0
>>     Run ./aer_inject <a parameter file as below>:
>>     AER
>>     PCI_ID 0000:e9:00.0
>>     COR_STATUS BAD_TLP
>>     HEADER_LOG 0 1 2 3
>>
>>     Log:
>> [   76.155963] pcieport 0000:e8:00.4: aer_inject: Injecting errors 
>> 00000040/00000000 into device 0000:e9:00.0
>> [   76.166966] pcieport 0000:e8:00.4: AER: Corrected error received: 
>> 0000:e9:00.0
>> [   76.175253] pci 0000:e9:00.0: PCIe Bus Error: severity=Corrected, 
>> type=Data Link Layer, (Receiver ID)
>> [   76.185633] pci 0000:e9:00.0:   device [8086:4940] error 
>> status/mask=00000040/00002000
>> [   76.194604] pci 0000:e9:00.0:    [ 6] BadTLP
>
> If you remove the timestamps, there will be less distraction here.  As
> I'm sure you know, the 0/n cover letter text doesn't really go
> anywhere except the email archives.  If this is potentially useful in
> the future, it should be in the actual patch commit logs.

Right, the intent is to show how it was tested.  Understood.

>
>> 2) Inject a non-fatal error to the RCiEP 0000:e8:01.0
>>     Run ./aer_inject <a parameter file as below>:
>>     AER
>>     PCI_ID 0000:e8:01.0
>>     UNCOR_STATUS COMP_ABORT
>>     HEADER_LOG 0 1 2 3
>
> I think maybe this could be written in a way that could be cut and
> pasted?

Good point.  Will do.

>
>>     Log:
>> [  117.791854] pcieport 0000:e8:00.4: aer_inject: Injecting errors 
>> 00000000/00008000 into device 0000:e8:01.0
>> [  117.804244] pcieport 0000:e8:00.4: AER: Uncorrected (Non-Fatal) 
>> error received: 0000:e8:01.0
>> [  117.814652] igen6_edac 0000:e8:01.0: PCIe Bus Error: 
>> severity=Uncorrected (Non-Fatal), type=Transaction Layer, (Completer 
>> ID)
>> [  117.828511] igen6_edac 0000:e8:01.0:   device [8086:0b25] error 
>> status/mask=00008000/00100000
>> [  117.839189] igen6_edac 0000:e8:01.0:    [15] CmpltAbrt
>> [  117.847365] igen6_edac 0000:e8:01.0: AER:   TLP Header: 00000000 
>> 00000001 00000002 00000003
>> [  117.857775] igen6_edac 0000:e8:01.0: AER: device recovery 
>> successful
>>
>> 3) Inject a fatal error to the RCiEP 0000:ed:01.0
>>     Run ./aer_inject <a parameter file as below>:
>>     AER
>>     PCI_ID 0000:ed:01.0
>>     UNCOR_STATUS MALF_TLP
>>     HEADER_LOG 0 1 2 3
>>
>>     Log:
>> [  131.511623] pcieport 0000:ed:00.4: aer_inject: Injecting errors 
>> 00000000/00040000 into device 0000:ed:01.0
>> [  131.523259] pcieport 0000:ed:00.4: AER: Uncorrected (Fatal) error 
>> received: 0000:ed:01.0
>> [  131.533842] igen6_edac 0000:ed:01.0: AER: PCIe Bus Error: 
>> severity=Uncorrected (Fatal), type=Inaccessible, (Unregistered Agent 
>> ID)
>> [  131.655618] igen6_edac 0000:ed:01.0: AER: device recovery 
>> successful
>>
>> Jonathan Cameron (1):
>>   PCI/AER: Extend AER error handling to RCECs
>>
>> Qiuxu Zhuo (6):
>>   pci_ids: Add class code and extended capability for RCEC
>>   PCI: Extend Root Port Driver to support RCEC
>>   PCI/portdrv: Add pcie_walk_rcec() to walk RCiEPs associated with 
>> RCEC
>>   PCI/AER: Apply function level reset to RCiEP on fatal error
>>   PCI: Add 'rcec' field to pci_dev for associated RCiEPs
>>   PCI/AER: Add RCEC AER error injection support
>>
>> Sean V Kelley (2):
>>   PCI/AER: Add RCEC AER handling
>>   PCI/PME: Add RCEC PME handling
>>
>
>>  drivers/pci/pcie/aer.c          | 36 +++++++++----
>>  drivers/pci/pcie/aer_inject.c   |  5 +-
>>  drivers/pci/pcie/err.c          | 90 
>> +++++++++++++++++++++++++++------
>>  drivers/pci/pcie/pme.c          | 15 ++++--
>>  drivers/pci/pcie/portdrv.h      |  2 +
>>  drivers/pci/pcie/portdrv_core.c | 90 
>> +++++++++++++++++++++++++++++++--
>>  drivers/pci/pcie/portdrv_pci.c  | 20 +++++++-
>>  include/linux/pci.h             |  3 ++
>>  include/linux/pci_ids.h         |  1 +
>>  include/uapi/linux/pci_regs.h   |  7 +++
>>  10 files changed, 233 insertions(+), 36 deletions(-)
>
> I always apply patches to topic branches based at my "master" branch
> (typically -rc1, so currently v5.8-rc1, but will soon be v5.9-rc1).
>
> If your series doesn't apply there (as this one doesn't), it saves me
> time if you tell me where it does apply.  I figured out that this
> applies cleanly on top of my pci/error branch, which does make sense.
>
> I'd actually *rather* have patches based on "master", even if I have
> to resolve conflicts, because that gives me the flexibility to squash
> in fixes and re-merge the topic branches.

Okay. Good to know as this time it was put on your pci branch. Will 
switch back to master.

Thanks,

Sean

>
> Bjorn

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