Date:   Thu, 01 Oct 2020 14:01:54 -0700
From:   "Sean V Kelley" <sean.v.kelley@...el.com>
To:     "Jonathan Cameron" <Jonathan.Cameron@...wei.com>
Cc:     "Sean V Kelley" <seanvk.dev@...gontracks.org>, bhelgaas@...gle.com,
        rafael.j.wysocki@...el.com, ashok.raj@...el.com,
        tony.luck@...el.com, sathyanarayanan.kuppuswamy@...el.com,
        qiuxu.zhuo@...el.com, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 00/13] Add RCEC handling to PCI/AER

On 1 Oct 2020, at 3:16, Jonathan Cameron wrote:

> On Wed, 30 Sep 2020 14:58:07 -0700
> Sean V Kelley <seanvk.dev@...gontracks.org> wrote:
>
>> From: Sean V Kelley <sean.v.kelley@...el.com>
>>
>> Changes since v6 [1]:
>>
>> - Remove unused includes in rcec.c.
>> - Add local variable for dev->rcec_ea.
>> - If no valid capability version then just fill in nextbusn = 0xff.
>> - Leave a blank line after pci_rcec_init(dev).
>> - Reword commit w/ "Attempt to do a function level reset for an RCiEP 
>> on fatal error."
>> - Change An RCiEP found on bus in range -> An RCiEP found on a 
>> different bus in range
>> - Remove special check on capability version if you fill in nextbusn 
>> = 0xff.
>> - Remove blank lines in pcie_link_rcec header.
>> - Fix indentation aer.c.
>> (Jonathan Cameron)
>>
>> - Relocate enabling of PME for RCECs to later RCEC handling additions 
>> to PME.
>> - Rename rcec_ext to rcec_ea.
>> - Remove rcec_cap as its use can be handled with rcec_ea.
>> - Add a forward declaration for struct rcec_ea.
>> - Rename pci_bridge_walk() to pci_walk_bridge() to match consistency 
>> with other usage.
>> - Separate changes to "reset_subordinate_devices" because it doesn't 
>> change the interface.
>> - Separate the use of "type", rename of "dev" to "bridge", the 
>> inversion of the condition and
>> use of pci_upstream_bridge() instead of dev->bus->self.
>> - Separate the conditional check (TYPE_ROOT_PORT and TYPE_DOWNSTREAM) 
>> for AER resets.
>> - Consider embedding RCiEP's parent RCEC in the rcec_ea struct. 
>> However, the
>> issue here is that we don't normally allocate the rcec_ea struct for 
>> RCiEPs and
>> the linkage of rcec_ea->rcec is not necessarily more clear.
>> - Provide more comment on the non-native case for clarity.
>> (Bjorn Helgaas)
>>
>> [1] 
>> https://lore.kernel.org/linux-pci/20200922213859.108826-1-seanvk.dev@oregontracks.org/
>>
>> 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.
>
> I took a look at the combined result of the series as well as 
> individual
> patches I've acked.  All looks good to me.
>
> Also ran a quick batch of tests with the non-native / no visible RCEC 
> case
> and that's working as expected.  Feels a bit odd too give a tested-by 
> for
> the case that touches only a tiny corner of the code, but if you want 
> to include
> it...
>
> Tested-by: Jonathan Cameron <Jonathan.Cameron@...wei.com> 
> #non-native/no RCEC

Much appreciated Jonathan.

Thanks,

Sean


>
> Thanks,
>
> Jonathan
>
>>
>>
>> Jonathan Cameron (1):
>>   PCI/AER: Extend AER error handling to RCECs
>>
>> Qiuxu Zhuo (5):
>>   PCI/RCEC: Add RCEC class code and extended capability
>>   PCI/RCEC: Bind RCEC devices to the Root Port driver
>>   PCI/AER: Apply function level reset to RCiEP on fatal error
>>   PCI/RCEC: Add RCiEP's linked RCEC to AER/ERR
>>   PCI/AER: Add RCEC AER error injection support
>>
>> Sean V Kelley (7):
>>   PCI/RCEC: Cache RCEC capabilities in pci_init_capabilities()
>>   PCI/ERR: Rename reset_link() to reset_subordinate_device()
>>   PCI/ERR: Use "bridge" for clarity in pcie_do_recovery()
>>   PCI/ERR: Limit AER resets in pcie_do_recovery()
>>   PCI/RCEC: Add pcie_link_rcec() to associate RCiEPs
>>   PCI/AER: Add pcie_walk_rcec() to RCEC AER handling
>>   PCI/PME: Add pcie_walk_rcec() to RCEC PME handling
>>
>>  drivers/pci/pci.h               |  25 ++++-
>>  drivers/pci/pcie/Makefile       |   2 +-
>>  drivers/pci/pcie/aer.c          |  36 ++++--
>>  drivers/pci/pcie/aer_inject.c   |   5 +-
>>  drivers/pci/pcie/err.c          | 109 +++++++++++++++----
>>  drivers/pci/pcie/pme.c          |  15 ++-
>>  drivers/pci/pcie/portdrv_core.c |   8 +-
>>  drivers/pci/pcie/portdrv_pci.c  |   8 +-
>>  drivers/pci/pcie/rcec.c         | 187 
>> ++++++++++++++++++++++++++++++++
>>  drivers/pci/probe.c             |   2 +
>>  include/linux/pci.h             |   5 +
>>  include/linux/pci_ids.h         |   1 +
>>  include/uapi/linux/pci_regs.h   |   7 ++
>>  13 files changed, 367 insertions(+), 43 deletions(-)
>>  create mode 100644 drivers/pci/pcie/rcec.c
>>
>> --
>> 2.28.0
>>

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