Re: [PATCH v11 16/23] cxl/pci: Introduce CXL Endpoint protocol error handlers

Jonathan Cameron
2025-09-10T13:23:40Z

On Tue, 26 Aug 2025 20:35:31 -0500
Terry Bowman <terry.bowman@amd.com> wrote:

> CXL Endpoint protocol errors are currently handled using PCI error
> handlers. The CXL Endpoint requires CXL specific handling in the case of
> uncorrectable error (UCE) handling not provided by the PCI handlers.
>
> Add CXL specific handlers for CXL Endpoints. Rename the existing
> cxl_error_handlers to be pci_error_handlers to more correctly indicate
> the error type and follow naming consistency.
>
> The PCI handlers will be called if the CXL device is not trained for
> alternate protocol (CXL). Update the CXL Endpoint PCI handlers to call the
> CXL UCE handlers.
>
> The existing EP UCE handler includes checks for various results. These are
> no longer needed because CXL UCE recovery will not be attempted. Implement
> cxl_handle_ras() to return PCI_ERS_RESULT_NONE or PCI_ERS_RESULT_PANIC. The
> CXL UCE handler is called by cxl_do_recovery() that acts on the return
> value. In the case of the PCI handler path, call panic() if the result is
> PCI_ERS_RESULT_PANIC.
>
> Signed-off-by: Terry Bowman <terry.bowman@amd.com>
> Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
>
> ---
> Changes in v10->v11:
> - cxl_error_detected() - Change handlers' scoped_guard() to guard() (Jonathan)
> - cxl_error_detected() - Remove extra line (Shiju)
> - Changes moved to core/ras.c (Terry)
> - cxl_error_detected(), remove 'ue' and return with function call. (Jonathan)
> - Remove extra space in documentation for PCI_ERS_RESULT_PANIC definition
> - Move #include "pci.h from cxl.h to core.h (Terry)
> - Remove unnecessary includes of cxl.h and core.h in mem.c (Terry)
Hi Terry,

A few suggested renames inline just because things like pci_cor_error_detected()
sounds like it should have nothing CXL specific in it.

Whilst it is clunky to use cxl_pci_cor_error_detected() I think that is
worth doing to avoid this potential confusion.

> diff --git a/drivers/cxl/core/ras.c b/drivers/cxl/core/ras.c
> index 42b6e0b092d5..b285448c2d9c 100644
> --- a/drivers/cxl/core/ras.c
> +++ b/drivers/cxl/core/ras.c

>
> -void cxl_cor_error_detected(struct pci_dev *pdev)
> +void cxl_cor_error_detected(struct device *dev)
> {
> + struct pci_dev *pdev = to_pci_dev(dev);
> struct cxl_dev_state *cxlds = pci_get_drvdata(pdev);
> - struct device *dev = &cxlds->cxlmd->dev;
> + struct device *cxlmd_dev = &cxlds->cxlmd->dev;
>
> - scoped_guard(device, dev) {

Dropping the scoped_guard() to guard() here makes it harder
to tell what is going on. I guess it isn't quite worth a precursor
patch unless there are several similar refactors to do.

> - if (!dev->driver) {
> - dev_warn(&pdev->dev,
> - "%s: memdev disabled, abort error handling\n",
> - dev_name(dev));
> - return;
> - }
> + guard(device)(cxlmd_dev);
>
> - if (cxlds->rcd)
> - cxl_handle_rdport_errors(cxlds);
> -
> - cxl_handle_cor_ras(&cxlds->cxlmd->dev, cxlds->serial, cxlds->regs.ras);
> + if (!cxlmd_dev->driver) {
> + dev_warn(&pdev->dev, "%s: memdev disabled, abort error handling", dev_name(dev));
> + return;
> }
> +
> + if (cxlds->rcd)
> + cxl_handle_rdport_errors(cxlds);
> +
> + cxl_handle_cor_ras(&cxlds->cxlmd->dev, cxlds->serial, cxlds->regs.ras);
> }
> EXPORT_SYMBOL_NS_GPL(cxl_cor_error_detected, "CXL");
>
> -pci_ers_result_t cxl_error_detected(struct pci_dev *pdev,
> - pci_channel_state_t state)
> +void pci_cor_error_detected(struct pci_dev *pdev)
> {
> + cxl_cor_error_detected(&pdev->dev);
> +}
> +EXPORT_SYMBOL_NS_GPL(pci_cor_error_detected, "CXL");

I'd go with a cxl_pci_ prefix for this to avoid impression it is is more
generic than that.

>
> +
> +pci_ers_result_t pci_error_detected(struct pci_dev *pdev,

Given this is CXL specific, probably makes sense to prefix to give
cxl_pci_error_detected()

Then when we see the call it is more obvious it isn't a 'generic'
PCI thing.

> + pci_channel_state_t error)
> +{
> + pci_ers_result_t rc;
> +
> + rc = cxl_error_detected(&pdev->dev);
> + if (rc == PCI_ERS_RESULT_PANIC)
> + panic("CXL cachemem error.");
> +
> + return rc;
> +}
> +EXPORT_SYMBOL_NS_GPL(pci_error_detected, "CXL");