linux-kernel - Re: [PATCH v2 1/4] PCI/AER: Store more information in aer_err

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Message-ID: <20240206172335.GA872811@bhelgaas>
Date: Tue, 6 Feb 2024 11:23:35 -0600
From: Bjorn Helgaas <helgaas@...nel.org>
To: "Wang, Qingshun" <qingshun.wang@...ux.intel.com>
Cc: linux-pci@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
	linux-acpi@...r.kernel.org, chao.p.peng@...ux.intel.com,
	erwin.tsaur@...el.com, feiting.wanyan@...el.com,
	qingshun.wang@...el.com, "Rafael J. Wysocki" <rafael@...nel.org>,
	Len Brown <lenb@...nel.org>, James Morse <james.morse@....com>,
	Tony Luck <tony.luck@...el.com>, Borislav Petkov <bp@...en8.de>,
	Davidlohr Bueso <dave@...olabs.net>,
	Jonathan Cameron <jonathan.cameron@...wei.com>,
	Dave Jiang <dave.jiang@...el.com>,
	Alison Schofield <alison.schofield@...el.com>,
	Vishal Verma <vishal.l.verma@...el.com>,
	Ira Weiny <ira.weiny@...el.com>,
	Dan Williams <dan.j.williams@...el.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Mahesh J Salgaonkar <mahesh@...ux.ibm.com>,
	Oliver O'Halloran <oohall@...il.com>,
	Miaohe Lin <linmiaohe@...wei.com>,
	Shiju Jose <shiju.jose@...wei.com>,
	Adam Preble <adam.c.preble@...el.com>, Li Yang <leoyang.li@....com>,
	Lukas Wunner <lukas@...ner.de>,
	Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>,
	Smita Koralahalli <Smita.KoralahalliChannabasappa@....com>,
	Robert Richter <rrichter@....com>, linux-kernel@...r.kernel.org,
	linux-cxl@...r.kernel.org, linux-edac@...r.kernel.org
Subject: Re: [PATCH v2 1/4] PCI/AER: Store more information in aer_err_info

On Wed, Feb 07, 2024 at 12:41:41AM +0800, Wang, Qingshun wrote:
> On Mon, Feb 05, 2024 at 05:12:31PM -0600, Bjorn Helgaas wrote:
> > On Thu, Jan 25, 2024 at 02:27:59PM +0800, Wang, Qingshun wrote:
> > > When Advisory Non-Fatal errors are raised, both correctable and
> > > uncorrectable error statuses will be set. The current kernel code cannot
> > > store both statuses at the same time, thus failing to handle ANFE properly.
> > > In addition, to avoid clearing UEs that are not ANFE by accident, UE
> > > severity and Device Status also need to be recorded: any fatal UE cannot
> > > be ANFE, and if Fatal/Non-Fatal Error Detected is set in Device Status, do
> > > not take any assumption and let UE handler to clear UE status.
> > > 
> > > Store status and mask of both correctable and uncorrectable errors in
> > > aer_err_info. The severity of UEs and the values of the Device Status
> > > register are also recorded, which will be used to determine UEs that should
> > > be handled by the ANFE handler. Refactor the rest of the code to use
> > > cor/uncor_status and cor/uncor_mask fields instead of status and mask
> > > fields.
> > 
> > There's a lot going on in this patch.  Could it possibly be split up a
> > bit, e.g., first tease apart aer_err_info.status/.mask into
> > .cor_status/mask and .uncor_status/mask, then add .uncor_severity,
> > then add the device_status bit separately?  If it could be split up, I
> > think the ANFE case would be easier to see.
> 
> Thanks for the feedback! Will split it up into two pacthes in the next
> version.

Or even three:

  1) tease apart aer_err_info.status/.mask into .cor_status/mask and
     .uncor_status/mask

  2) add .uncor_severity

  3) add device_status

Looking at this again, I'm a little confused about 2) and 3).  I see
the new read of PCI_ERR_UNCOR_SEVER into .uncor_severity, but there's
no actual *use* of it.

Same for 3), I see the new read of PCI_EXP_DEVSTA, but AFAICS there's
no use of that value.

We should have the addition of these new values in the same patch
that *uses* them.

Bjorn