linux-kernel - Re: [PATCH 2/6 v6] ACPI: extlog: Trace CPER PCI Express Error Section

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Message-ID: <2351924.vFx2qVVIhK@fdefranc-mobl3>
Date: Fri, 31 Oct 2025 11:18:27 +0100
From: "Fabio M. De Francesco" <fabio.m.de.francesco@...ux.intel.com>
To: Jonathan Cameron <jonathan.cameron@...wei.com>
Cc: linux-cxl@...r.kernel.org, "Rafael J . Wysocki" <rafael@...nel.org>,
 Len Brown <lenb@...nel.org>, Tony Luck <tony.luck@...el.com>,
 Borislav Petkov <bp@...en8.de>, Hanjun Guo <guohanjun@...wei.com>,
 Mauro Carvalho Chehab <mchehab@...nel.org>,
 Shuai Xue <xueshuai@...ux.alibaba.com>, Davidlohr Bueso <dave@...olabs.net>,
 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>,
 Mahesh J Salgaonkar <mahesh@...ux.ibm.com>,
 Oliver O'Halloran <oohall@...il.com>, Bjorn Helgaas <bhelgaas@...gle.com>,
 Sunil V L <sunilvl@...tanamicro.com>, Xiaofei Tan <tanxiaofei@...wei.com>,
 Mario Limonciello <mario.limonciello@....com>,
 Huacai Chen <chenhuacai@...nel.org>,
 Heinrich Schuchardt <heinrich.schuchardt@...onical.com>,
 Arnd Bergmann <arnd@...db.de>, Peter Zijlstra <peterz@...radead.org>,
 Ingo Molnar <mingo@...nel.org>, Guo Weikang <guoweikang.kernel@...il.com>,
 Xin Li <xin@...or.com>, Will Deacon <will@...nel.org>,
 Huang Yiwei <quic_hyiwei@...cinc.com>, Gavin Shan <gshan@...hat.com>,
 Smita Koralahalli <Smita.KoralahalliChannabasappa@....com>,
 Uwe Kleine-König <u.kleine-koenig@...libre.com>,
 Li Ming <ming.li@...omail.com>,
 Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
 Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>,
 Karolina Stolarek <karolina.stolarek@...cle.com>,
 Jon Pan-Doh <pandoh@...gle.com>, Lukas Wunner <lukas@...ner.de>,
 Shiju Jose <shiju.jose@...wei.com>, linux-kernel@...r.kernel.org,
 linux-acpi@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
 linux-pci@...r.kernel.org
Subject: Re: [PATCH 2/6 v6] ACPI: extlog: Trace CPER PCI Express Error Section

On Tuesday, October 28, 2025 3:48:16 PM Central European Standard Time Jonathan Cameron wrote:
> On Thu, 23 Oct 2025 14:25:37 +0200
> "Fabio M. De Francesco" <fabio.m.de.francesco@...ux.intel.com> wrote:
> 
> > I/O Machine Check Architecture events may signal failing PCIe components
> > or links. The AER event contains details on what was happening on the wire
> > when the error was signaled.
> > 
> > Trace the CPER PCIe Error section (UEFI v2.10, Appendix N.2.7) reported
> > by the I/O MCA.
> > 
> > Cc: Dan Williams <dan.j.williams@...el.com>
> > Reviewed-by: Dave Jiang <dave.jiang@...el.com>
> > Reviewed-by: Jonathan Cameron <jonathan.cameron@...wei.com>
> > Signed-off-by: Fabio M. De Francesco <fabio.m.de.francesco@...ux.intel.com>
> Hi Fabio,
> 
> Was taking a fresh look at this as a precursor to looking at later
> patches in series and spotted something that I'm doubtful about.
> 
> > diff --git a/drivers/acpi/acpi_extlog.c b/drivers/acpi/acpi_extlog.c
> > index 47d11cb5c912..cefe8d2d8aff 100644
> > --- a/drivers/acpi/acpi_extlog.c
> > +++ b/drivers/acpi/acpi_extlog.c
> > @@ -132,6 +132,34 @@ static int print_extlog_rcd(const char *pfx,
> >  	return 1;
> >  }
> >  
> > +static void extlog_print_pcie(struct cper_sec_pcie *pcie_err,
> > +			      int severity)
> > +{
> > +	struct aer_capability_regs *aer;
> > +	struct pci_dev *pdev;
> > +	unsigned int devfn;
> > +	unsigned int bus;
> > +	int aer_severity;
> > +	int domain;
> > +
> > +	if (!(pcie_err->validation_bits & CPER_PCIE_VALID_DEVICE_ID ||
> > +	      pcie_err->validation_bits & CPER_PCIE_VALID_AER_INFO))
> 
> Looking again, I'm not sure this is as intended.  Is the aim to
> allow for either one of these two?  Or check that that are both present? 
> That is should it be !(A && B) rather than !(A || B)?
> 
Hi Jonathan,

You're right. We need to check that both are true and return if they are 
not, then the statement has to be !(A && B).

Thank you,

Fabio 
> 
> > +		return;
> > +
> > +	aer_severity = cper_severity_to_aer(severity);
> > +	aer = (struct aer_capability_regs *)pcie_err->aer_info;
> > +	domain = pcie_err->device_id.segment;
> > +	bus = pcie_err->device_id.bus;
> > +	devfn = PCI_DEVFN(pcie_err->device_id.device,
> > +			  pcie_err->device_id.function);
> > +	pdev = pci_get_domain_bus_and_slot(domain, bus, devfn);
> > +	if (!pdev)
> > +		return;
> > +
> > +	pci_print_aer(pdev, aer_severity, aer);
> > +	pci_dev_put(pdev);
> > +}
> 
>