linux-kernel - Re: [PATCH v7 12/17] cxl/pci: Add error handler for CXL PCIe Port RAS errors

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Message-ID: <67b4c04e96439_2d2c29478@dwillia2-xfh.jf.intel.com.notmuch>
Date: Tue, 18 Feb 2025 09:15:58 -0800
From: Dan Williams <dan.j.williams@...el.com>
To: "Bowman, Terry" <terry.bowman@....com>, Dan Williams
	<dan.j.williams@...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>, <bhelgaas@...gle.com>, <mahesh@...ux.ibm.com>,
	<ira.weiny@...el.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>
Subject: Re: [PATCH v7 12/17] cxl/pci: Add error handler for CXL PCIe Port
 RAS errors

Bowman, Terry wrote:
[..]
> >> Or, if you like I can start to add the CXL kfifo changes now.
> > I feel like there's enough examples of kfifo in error handling to make
> > this not too burdensome, but let me know if you disagree. Otherwise,
> > would need to spend the time to figure out how to keep the test
> > environment functioning (cxl-test depends on modular core builds).
> 
> Thanks for the feedback. Yes, there are several examples and Smita is using for
> FW-first as well. Correct me if I'm wrong but the goal in this case is
> for the FW-first and OS-first to use the same kfifo.

Not necessarily, the leaf handlers should unify around
cxl_do_recovery(), however you will notice that CPER PCIe AER events get
routed to the aer_recover_ring kfifo and native PCIe AER events get
collected by the aer_rpc.aer_fifo.  Both of those route to
pcie_do_recovery() on the backend.

The CXL kfifo is to allow the CXL subsystem to remain modular and only
minimally burden the PCIe AER flow with just enough logic to determine
"not a PCIe AER event".