linux-kernel - Re: [RFC PATCH 3/6] PCI/AER: Enable RCEC to report internal error for CXL root port

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Message-ID: <662134e290d89_5eec229450@dwillia2-mobl3.amr.corp.intel.com.notmuch>
Date: Thu, 18 Apr 2024 07:57:38 -0700
From: Dan Williams <dan.j.williams@...el.com>
To: "Li, Ming" <ming4.li@...el.com>, Terry Bowman <Terry.Bowman@....com>,
	<dan.j.williams@...el.com>, <rrichter@....com>
CC: <linux-cxl@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH 3/6] PCI/AER: Enable RCEC to report internal error
 for CXL root port

Li, Ming wrote:
> On 4/16/2024 10:46 PM, Terry Bowman wrote:
> > The driver support is much simpler if RCEC does not handle VH protocol errors. Is there 
> > a reason to forward root port VH mode protocol errors to an RCEC rather than consume 
> > in the root port's AER driver and forward to CXL error handler? 
> > 
> I agree that is simpler if only root port handle VH protocol errors,
> but I think that software has no chance to choose if VH protocol
> errors reported to RCEC or root port, it depends on platform
> implementation. So I think we should support both cases.

The question is whether the CXL spec RDPAS behavior causes any problems
for platforms that follow PCIe rather than CXL reporting flows for
root-port errors. I.e. does it cause problems if Linux starts scanning
root ports on RCEC notifications?

I do think the lookup needs to change to be based on CXL host-bridge
detection and not CXL-type-3 endpoint detection, but otherwise it looks
like CXL spec wants to invalidate PCIe spec expectations.