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

From: Jonathan Cameron <[email-masked]>
Date: Tue, 28 Oct 2025 14:48:16 +0000

On Thu, 23 Oct 2025 14:25:37 +0200
"Fabio M. De Francesco" <[email-masked]> 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 <[email-masked]>
> Reviewed-by: Dave Jiang <[email-masked]>
> Reviewed-by: Jonathan Cameron <[email-masked]>
> Signed-off-by: Fabio M. De Francesco <[email-masked]>
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)?

> +		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);
> +}