Re: [PATCH v4 12/15] cxl/pci: Add error handler for CXL PCIe Port RAS errors

Li Ming
2024-12-12T02:19:46Z

On 12/12/2024 7:39 AM, Terry Bowman wrote:
> Introduce correctable and uncorrectable CXL PCIe port protocol error
> handlers.
>
> The handlers will be called with a 'struct pci_dev' parameter
> indicating the CXL Port device requiring handling. The CXL PCIe Port
> device's underlying 'struct device' will match the Port device in the
> CXL topology.
>
> Use the PCIe Port's device object to find the matching Upstream Switch
> Port, Downstream Switch Port, or Root Port in the CXL topology. The
> matching device will contain a reference to the RAS register block used to
> handle and log the error.
>
> Invoke the existing __cxl_handle_ras() or __cxl_handle_cor_ras() passing
> a reference to the RAS registers as a parameter. These functions will use
> the register reference to clear the device's RAS status.
>
> Future patches will assign the error handlers and add trace logging.
>
> Signed-off-by: Terry Bowman <terry.bowman@amd.com>
> ---
> drivers/cxl/core/pci.c | 61 ++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 61 insertions(+)
>
> diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c
> index 89f8d65d71ce..52afaedf5171 100644
> --- a/drivers/cxl/core/pci.c
> +++ b/drivers/cxl/core/pci.c
> @@ -772,6 +772,67 @@ 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)
> +{
> + void __iomem *ras_base;
> + struct cxl_port *port;
> +
> + 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);
> + ras_base = dport ? dport->regs.ras : NULL;
> + if (port)
> + put_device(&port->dev);
> + return ras_base;
> + } 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;

I think that is no need to check 'port', just directly use 'ras_base = port->uport_regs.ras;', because match_uport() already checks it, returned port_dev must be a port.

Ming