linux-kernel - Re: [PATCH v2 12/14] cxl/pci: Add error handler for CXL PCIe port RAS errors

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Message-ID: <20241030160349.000040d4@Huawei.com>
Date: Wed, 30 Oct 2024 16:03:49 +0000
From: Jonathan Cameron <Jonathan.Cameron@...wei.com>
To: Terry Bowman <terry.bowman@....com>
CC: <ming4.li@...el.com>, <linux-cxl@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <linux-pci@...r.kernel.org>,
	<dave@...olabs.net>, <dave.jiang@...el.com>, <alison.schofield@...el.com>,
	<vishal.l.verma@...el.com>, <dan.j.williams@...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>
Subject: Re: [PATCH v2 12/14] cxl/pci: Add error handler for CXL PCIe port
 RAS errors

On Fri, 25 Oct 2024 16:03:03 -0500
Terry Bowman <terry.bowman@....com> wrote:

> Introduce correctable and uncorrectable CXL PCIe port handlers.
> 
> Use the PCIe port's device object to find the matching port or
> downstream port in the CXL topology. The matching port or downstream
> port will include the cached RAS register block.
> 
> Invoke the existing __cxl_handle_ras() with the RAS registers as a
> parameter. __cxl_handle_ras() will log the RAS errors (if present)
> and clear the RAS status.
> 
> Signed-off-by: Terry Bowman <terry.bowman@....com>
> ---
>  drivers/cxl/core/pci.c | 59 ++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 59 insertions(+)
> 
> diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c
> index bb2fd7d04c4f..adb184d346ae 100644
> --- a/drivers/cxl/core/pci.c
> +++ b/drivers/cxl/core/pci.c
> @@ -772,6 +772,65 @@ static void cxl_disable_rch_root_ints(struct cxl_dport *dport)
>  	writel(aer_cmd, aer_base + PCI_ERR_ROOT_COMMAND);
>  }
>  
> +static int match_uport(struct device *dev, const void *data)
> +{
> +	struct device *uport_dev = (struct device *)data;
> +	struct cxl_port *port;
> +
> +	if (!is_cxl_port(dev))
> +		return 0;
> +
> +	port = to_cxl_port(dev);
> +
> +	return port->uport_dev == uport_dev;
> +}
> +
> +static void __iomem *cxl_pci_port_ras(struct pci_dev *pdev)
> +{
> +	struct cxl_port *port __free(put_cxl_port) = NULL;
> +	void __iomem *ras_base = NULL;
> +
> +	if (!pdev)
> +		return NULL;
> +
> +	if ((pci_pcie_type(pdev) == PCI_EXP_TYPE_ROOT_PORT) ||
> +	    (pci_pcie_type(pdev) == PCI_EXP_TYPE_DOWNSTREAM)) {
> +		struct cxl_dport *dport;
> +
> +		port = find_cxl_port(&pdev->dev, &dport);

Scope of port is messy as the constructor and destructor
are not well associated. I'd drag a copy into each leg so they can
remain closer to each other.
Or don't use __free() as it's not adding much here.

> +		ras_base = dport ? dport->regs.ras : NULL;	
> +	} else if (pci_pcie_type(pdev) == PCI_EXP_TYPE_UPSTREAM) {
> +		struct device *port_dev;
> +
> +		port_dev = bus_find_device(&cxl_bus_type, NULL, &pdev->dev,
> +					   match_uport);
> +		if (!port_dev)
> +			return NULL;
> +
> +		port = to_cxl_port(port_dev);
> +		ras_base = port ? port->uport_regs.ras : NULL;
> +	}
> +
> +	return ras_base;
> +}
> +
> +static void cxl_port_cor_error_detected(struct pci_dev *pdev)
> +{
> +	void __iomem *ras_base = cxl_pci_port_ras(pdev);
> +
> +	__cxl_handle_cor_ras(&pdev->dev, ras_base);
> +}
> +
> +static bool cxl_port_error_detected(struct pci_dev *pdev)
> +{
> +	void __iomem *ras_base = cxl_pci_port_ras(pdev);
> +	bool ue;
> +
> +	ue = __cxl_handle_ras(&pdev->dev, ras_base);
> +
> +	return ue;
> +}
> +
>  void cxl_uport_init_ras_reporting(struct cxl_port *port)
>  {
>  	/* uport may have more than 1 downstream EP. Check if already mapped. */