linux-kernel - Re: [PATCH v5 16/16] PCI/AER: Enable internal errors for CXL Upstream and Downstream Switch Ports

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Message-ID: <67897d584caf5_1be60929453@iweiny-mobl.notmuch>
Date: Thu, 16 Jan 2025 15:42:48 -0600
From: Ira Weiny <ira.weiny@...el.com>
To: "Bowman, Terry" <terry.bowman@....com>, Ira Weiny <ira.weiny@...el.com>,
	<linux-cxl@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-pci@...r.kernel.org>, <nifan.cxl@...il.com>, <dave@...olabs.net>,
	<jonathan.cameron@...wei.com>, <dave.jiang@...el.com>,
	<alison.schofield@...el.com>, <vishal.l.verma@...el.com>,
	<dan.j.williams@...el.com>, <bhelgaas@...gle.com>, <mahesh@...ux.ibm.com>,
	<oohall@...il.com>, <Benjamin.Cheatham@....com>, <rrichter@....com>,
	<nathan.fontenot@....com>, <Smita.KoralahalliChannabasappa@....com>,
	<lukas@...ner.de>, <ming.li@...omail.com>,
	<PradeepVineshReddy.Kodamati@....com>, <alucerop@....com>
Subject: Re: [PATCH v5 16/16] PCI/AER: Enable internal errors for CXL
 Upstream and Downstream Switch Ports

Bowman, Terry wrote:
> 
> 
> 
> On 1/14/2025 5:45 PM, Ira Weiny wrote:
> > Bowman, Terry wrote:
> >>
> >>
> >> On 1/14/2025 5:26 PM, Ira Weiny wrote:
> >>> Terry Bowman wrote:
> >>>> The AER service driver enables PCIe Uncorrectable Internal Errors (UIE) and
> >>>> Correctable Internal errors (CIE) for CXL Root Ports. The UIE and CIE are
> >>>> used in reporting CXL Protocol Errors. The same UIE/CIE enablement is
> >>>> needed for CXL Upstream Switch Ports and CXL Downstream Switch Ports
> >>>> inorder to notify the associated Root Port and OS.[1]
> >>>>
> >>>> Export the AER service driver's pci_aer_unmask_internal_errors() function
> >>>> to CXL namespace.
> >>>>
> >>>> Remove the function's dependency on the CONFIG_PCIEAER_CXL kernel config
> >>>> because it is now an exported function.
> >>> This seems wrong to me.  As of this patch CXL_PCI requires PCIEAER_CXL for
> >>> the AER code to handle the errors which were just enabled.
> >>>
> >>> To keep PCIEAER_CXL optional pci_aer_unmask_internal_errors() should be
> >>> stubbed out in aer.h if !CONFIG_PCIEAER_CXL.
> >>>
> >>> Ira
> >> Bjorn (I believe in v1 or v2) directed me to remove
> >> pci_aer_unmask_internal_errors() dependency on PCIEAER_CXL because it is
> >> now exported. He wants the behavior for other users (and subsystems) to
> >> be consistent with/without the PCIEAER_CXL setting.
> >>
> > I see...  If PCIEAER_CXL is not enabled why even set the cxl error
> > handlers and enable these?
> >
> > I guess this is just adding some code which eventually calls
> > handles_cxl_errors() which returns false in the !PCIEAER_CXL case?
> >
> > Ira
> 
> Re-sending because I somehow sent from Outlook earlier.
> 
> cxl_dport_init_ras_reporting() and cxl_uport_init_ras_reporting() assign the error 
> handlers and are within #ifdef PCIEAER_CXL. The stubs are in cxl.h.
> 
> Correct. handles_cxl_errors() returns false in the !PCIEAER_CXL case.
> 

That is a bit convoluted...  But I'm not sure how to get the cross Kconfig
dependencies set to eliminate the set up.  :-/

So I guess it is fine.

Ira