Re: [PATCH v3 7/7] acpi/ghes, cxl/pci: Process CXL CPER Protocol Errors

Jonathan Cameron
2024-11-26T16:05:32Z

On Tue, 19 Nov 2024 00:39:15 +0000
Smita Koralahalli <Smita.KoralahalliChannabasappa@amd.com> wrote:

> When PCIe AER is in FW-First, OS should process CXL Protocol errors from
> CPER records. Introduce support for handling and logging CXL Protocol
> errors.
>
> The defined trace events cxl_aer_uncorrectable_error and
> cxl_aer_correctable_error trace native CXL AER endpoint errors, while
> cxl_cper_trace_corr_prot_err and cxl_cper_trace_uncorr_prot_err
> trace native CXL AER port errors. Reuse both sets to trace FW-First
> protocol errors.
>
> Since the CXL code is required to be called from process context and
> GHES is in interrupt context, use workqueues for processing.
>
> Similar to CXL CPER event handling, use kfifo to handle errors as it
> simplifies queue processing by providing lock free fifo operations.
>
> Add the ability for the CXL sub-system to register a workqueue to
> process CXL CPER protocol errors.
>
> Signed-off-by: Smita Koralahalli <Smita.KoralahalliChannabasappa@amd.com>

A few minor comments inline.

Thanks

Jonathan

> diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c
> index 4ede038a7148..c992b34c290b 100644
> --- a/drivers/cxl/core/pci.c
> +++ b/drivers/cxl/core/pci.c
> @@ -650,6 +650,56 @@ void read_cdat_data(struct cxl_port *port)
> }
> EXPORT_SYMBOL_NS_GPL(read_cdat_data, CXL);
>
> +void cxl_cper_trace_corr_prot_err(struct pci_dev *pdev, bool flag,
> + struct cxl_ras_capability_regs ras_cap)
> +{
> + struct cxl_dev_state *cxlds;
> + u32 status;
> +
> + status = ras_cap.cor_status & ~ras_cap.cor_mask;
> +
> + if (!flag) {

As below. Name of flag is not very helpful when reading the code.
Perhaps we can rename?

> + trace_cxl_port_aer_correctable_error(&pdev->dev, status);
> + return;
> + }
> +
> + cxlds = pci_get_drvdata(pdev);
> + if (!cxlds)
> + return;
> +
> + trace_cxl_aer_correctable_error(cxlds->cxlmd, status);
> +}
> +EXPORT_SYMBOL_NS_GPL(cxl_cper_trace_corr_prot_err, CXL);
> +
> +void cxl_cper_trace_uncorr_prot_err(struct pci_dev *pdev, bool flag,
> + struct cxl_ras_capability_regs ras_cap)
> +{
> + struct cxl_dev_state *cxlds;
> + u32 status, fe;
> +
> + status = ras_cap.uncor_status & ~ras_cap.uncor_mask;
> +
> + if (hweight32(status) > 1)
> + fe = BIT(FIELD_GET(CXL_RAS_CAP_CONTROL_FE_MASK,
> + ras_cap.cap_control));
> + else
> + fe = status;
> +
> + if (!flag) {

Why does a bool named flag indicate it's a port error?

> + trace_cxl_port_aer_uncorrectable_error(&pdev->dev, status, fe,
> + ras_cap.header_log);
> + return;
> + }
> +
> + cxlds = pci_get_drvdata(pdev);
> + if (!cxlds)
> + return;
> +
> + trace_cxl_aer_uncorrectable_error(cxlds->cxlmd, status, fe,
> + ras_cap.header_log);
> +}
> +EXPORT_SYMBOL_NS_GPL(cxl_cper_trace_uncorr_prot_err, CXL);
> +
> static void __cxl_handle_cor_ras(struct device *dev,
> void __iomem *ras_base)
> {
> diff --git a/drivers/cxl/cxlpci.h b/drivers/cxl/cxlpci.h
> index 4da07727ab9c..5e4aa8681937 100644
> --- a/drivers/cxl/cxlpci.h
> +++ b/drivers/cxl/cxlpci.h
> @@ -129,4 +129,10 @@ void read_cdat_data(struct cxl_port *port);
> void cxl_cor_error_detected(struct pci_dev *pdev);
> pci_ers_result_t cxl_error_detected(struct pci_dev *pdev,
> pci_channel_state_t state);
> +
> +struct cxl_ras_capability_regs;
> +void cxl_cper_trace_corr_prot_err(struct pci_dev *pdev, bool flag,
> + struct cxl_ras_capability_regs ras_cap);
> +void cxl_cper_trace_uncorr_prot_err(struct pci_dev *pdev, bool flag,
> + struct cxl_ras_capability_regs ras_cap);
> #endif /* __CXL_PCI_H__ */
> diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
> index 88a14d7baa65..e261abe60e90 100644
> --- a/drivers/cxl/pci.c
> +++ b/drivers/cxl/pci.c
> @@ -1067,6 +1067,53 @@ static void cxl_cper_work_fn(struct work_struct *work)
> }
> static DECLARE_WORK(cxl_cper_work, cxl_cper_work_fn);
>
> +static void cxl_cper_handle_prot_err(struct cxl_cper_prot_err_work_data *data)
> +{
> + unsigned int devfn = PCI_DEVFN(data->prot_err.agent_addr.device,
> + data->prot_err.agent_addr.function);
> + struct pci_dev *pdev __free(pci_dev_put) =
> + pci_get_domain_bus_and_slot(
> + data->prot_err.agent_addr.segment,
> + data->prot_err.agent_addr.bus,
> + devfn
> + );
pci_get_domain_bus_and_slot(data->prot_err.agent_addr.segment,
data->prot_err.agent_addr.bus,
devfn);

> + int port_type;
> +
> + if (!pdev)
> + return;
> +
> + guard(device)(&pdev->dev);
> + if (pdev->driver != &cxl_pci_driver)
> + return;
> +
> + port_type = pci_pcie_type(pdev);
> + if (port_type == PCI_EXP_TYPE_ROOT_PORT ||
> + port_type == PCI_EXP_TYPE_DOWNSTREAM ||
> + port_type == PCI_EXP_TYPE_UPSTREAM) {
> + if (data->severity == AER_CORRECTABLE)
> + cxl_cper_trace_corr_prot_err(pdev, false, data->ras_cap);
> + else
> + cxl_cper_trace_uncorr_prot_err(pdev, false, data->ras_cap);
> +
> + return;
> + }
> +
> + if (data->severity == AER_CORRECTABLE)
> + cxl_cper_trace_corr_prot_err(pdev, true, data->ras_cap);
> + else
> + cxl_cper_trace_uncorr_prot_err(pdev, true, data->ras_cap);
> +
> +}

> static int __init cxl_pci_driver_init(void)
> {
> int rc;
> @@ -1079,13 +1126,21 @@ static int __init cxl_pci_driver_init(void)
> if (rc)
> pci_unregister_driver(&cxl_pci_driver);
>
> + rc = cxl_cper_register_prot_err_work(&cxl_cper_prot_err_work);
> + if (rc) {
> + cxl_cper_unregister_event_work(&cxl_cper_work);
> + pci_unregister_driver(&cxl_pci_driver);
I'd switch this to a goto style for error handling.

> + }
> +
> return rc;

that is
return 0;

err_unregister_event_work:
cxl_cper_unregister_event_work(&cxl_cper_work);
err_unreg:
pci_unregister_driver(&cxl_pci_driver);
return rc;
> }