On Wed, 26 Mar 2025 20:47:05 -0500
Terry Bowman <terry.bowman@xxxxxxx> wrote:
> The AER service driver includes a CXL-specific kfifo, intended to forward
> CXL errors to the CXL driver. However, the forwarding functionality is
> currently unimplemented. Update the AER driver to enable error forwarding
> to the CXL driver.
>
> Modify the AER service driver's handle_error_source(), which is called from
> process_aer_err_devices(), to distinguish between PCIe and CXL errors.
>
> Rename and update is_internal_error() to is_cxl_error(). Ensuring it
> checks both the 'struct aer_info::is_cxl' flag and the AER internal error
> masks.
>
> If the error is a standard PCIe error then continue calling pcie_aer_handle_error()
> as done in the current AER driver.
>
> If the error is a CXL-related error then forward it to the CXL driver for
> handling using the kfifo mechanism.
>
> Introduce a new function forward_cxl_error(), which constructs a CXL
> protocol error context using cxl_create_prot_err_info(). This context is
> then passed to the CXL driver via kfifo using a 'struct work_struct'.
>
> Signed-off-by: Terry Bowman <terry.bowman@xxxxxxx>
Hi Terry,
Finally got back to this. I'm not following how some of the reference
counting in here is working. It might be fine but there is a lot
taking then dropping device references - some of which are taken again later.
> @@ -1082,10 +1094,44 @@ static void cxl_rch_enable_rcec(struct pci_dev *rcec)
> pci_info(rcec, "CXL: Internal errors unmasked");
> }
>
> +static void forward_cxl_error(struct pci_dev *_pdev, struct aer_err_info *info)
> +{
> + int severity = info->severity;
So far this variable isn't really justified. Maybe it makes sense later in the
series?
> + struct cxl_prot_err_work_data wd;
> + struct cxl_prot_error_info *err_info = &wd.err_info;
Similarly. Why not just use this directly in the call below?
> + struct pci_dev *pdev __free(pci_dev_put) = pci_dev_get(_pdev);
Can you talk me through the reference counting? You take one pci device reference
here....
> +
> + if (!cxl_create_prot_err_info) {
> + pci_err(pdev, "Failed. CXL-AER interface not initialized.");
> + return;
> + }
> +
> + if (cxl_create_prot_err_info(pdev, severity, err_info)) {
...but the implementation of this also takes once internally. Can we skip that
internal one and document that it is always take by the caller?
> + pci_err(pdev, "Failed to create CXL protocol error information");
> + return;
> + }
> +
> + struct device *cxl_dev __free(put_device) = get_device(err_info->dev);
Also this one. A reference was acquired and dropped in cxl_create_prot_err_info()
followed by retaking it here. How do we know it is still about by this call
and once we pull it off the kfifo later?
> +
> + if (!kfifo_put(&cxl_prot_err_fifo, wd)) {
> + pr_err_ratelimited("CXL kfifo overflow\n");
> + return;
> + }
> +
> + schedule_work(cxl_prot_err_work);
> +}
> +
Thanks,
Jonathan
