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Message-ID: <451bbab4-59b3-4ac7-a894-b05198d7062f@linux.intel.com>
Date: Wed, 4 Jun 2025 16:58:50 -0700
From: Sathyanarayanan Kuppuswamy <sathyanarayanan.kuppuswamy@...ux.intel.com>
To: Terry Bowman <terry.bowman@....com>, PradeepVineshReddy.Kodamati@....com,
dave@...olabs.net, jonathan.cameron@...wei.com, dave.jiang@...el.com,
alison.schofield@...el.com, vishal.l.verma@...el.com, ira.weiny@...el.com,
dan.j.williams@...el.com, bhelgaas@...gle.com, bp@...en8.de,
ming.li@...omail.com, shiju.jose@...wei.com, dan.carpenter@...aro.org,
Smita.KoralahalliChannabasappa@....com, kobayashi.da-06@...itsu.com,
yanfei.xu@...el.com, rrichter@....com, peterz@...radead.org, colyli@...e.de,
uaisheng.ye@...el.com, fabio.m.de.francesco@...ux.intel.com,
ilpo.jarvinen@...ux.intel.com, yazen.ghannam@....com,
linux-cxl@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-pci@...r.kernel.org
Subject: Re: [PATCH v9 04/16] PCI/AER: Dequeue forwarded CXL error
On 6/3/25 10:22 AM, Terry Bowman wrote:
> The AER driver is now designed to forward CXL protocol errors to the CXL
> driver. Update the CXL driver with functionality to dequeue the forwarded
> CXL error from the kfifo. Also, update the CXL driver to begin the protocol
> error handling processing using the work received from the FIFO.
>
> Introduce function cxl_prot_err_work_fn() to dequeue work forwarded by the
> AER service driver. This will begin the CXL protocol error processing
> with a call to cxl_handle_prot_error().
>
> Update cxl/core/ras.c by adding cxl_rch_handle_error_iter() that was
> previously in the AER driver.
>
> Introduce sbdf_to_pci() to take the SBDF values from 'struct cxl_prot_error_info'
> and use in discovering the erring PCI device. Make scope based reference
> increments/decrements for the discovered PCI device and the associated
> CXL device.
>
> Implement cxl_handle_prot_error() to differentiate between Restricted CXL
> Host (RCH) protocol errors and CXL virtual host (VH) protocol errors.
> RCH errors will be processed with a call to walk the associated Root
> Complex Event Collector's (RCEC) secondary bus looking for the Root Complex
> Integrated Endpoint (RCiEP) to handle the RCH error. Export pcie_walk_rcec()
> so the CXL driver can walk the RCEC's downstream bus, searching for
> the RCiEP.
>
> VH correctable error (CE) processing will call the CXL CE handler. VH
> uncorrectable errors (UCE) will call cxl_do_recovery(), implemented as a
> stub for now and to be updated in future patch. Export pci_aer_clean_fatal_status()
> and pci_clean_device_status() used to clean up AER status after handling.
>
> Signed-off-by: Terry Bowman <terry.bowman@....com>
> ---
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
> drivers/cxl/core/ras.c | 92 +++++++++++++++++++++++++++++++++++++++++
> drivers/pci/pci.c | 1 +
> drivers/pci/pci.h | 8 ----
> drivers/pci/pcie/aer.c | 1 +
> drivers/pci/pcie/rcec.c | 1 +
> include/linux/aer.h | 2 +
> include/linux/pci.h | 10 +++++
> 7 files changed, 107 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/cxl/core/ras.c b/drivers/cxl/core/ras.c
> index d35525e79e04..9ed5c682e128 100644
> --- a/drivers/cxl/core/ras.c
> +++ b/drivers/cxl/core/ras.c
> @@ -110,8 +110,100 @@ static DECLARE_WORK(cxl_cper_prot_err_work, cxl_cper_prot_err_work_fn);
>
> #ifdef CONFIG_PCIEAER_CXL
>
> +static void cxl_do_recovery(struct pci_dev *pdev)
> +{
> +}
> +
> +static int cxl_rch_handle_error_iter(struct pci_dev *pdev, void *data)
> +{
> + struct cxl_prot_error_info *err_info = data;
> + struct pci_dev *pdev_ref __free(pci_dev_put) = pci_dev_get(pdev);
> + struct cxl_dev_state *cxlds;
> +
> + /*
> + * The capability, status, and control fields in Device 0,
> + * Function 0 DVSEC control the CXL functionality of the
> + * entire device (CXL 3.0, 8.1.3).
Nit: I think you give spec references with different versions across your code (v3.0, v3.1, v3.2).
May be you can stick to the latest?
> + */
> + if (pdev->devfn != PCI_DEVFN(0, 0))
> + return 0;
> +
> + /*
> + * CXL Memory Devices must have the 502h class code set (CXL
> + * 3.0, 8.1.12.1).
> + */
> + if ((pdev->class >> 8) != PCI_CLASS_MEMORY_CXL)
> + return 0;
> +
> + if (!is_cxl_memdev(&pdev->dev) || !pdev->dev.driver)
> + return 0;
> +
> + cxlds = pci_get_drvdata(pdev);
> + struct device *dev __free(put_device) = get_device(&cxlds->cxlmd->dev);
> +
> + if (err_info->severity == AER_CORRECTABLE)
> + cxl_cor_error_detected(pdev);
> + else
> + cxl_do_recovery(pdev);
> +
> + return 1;
> +}
> +
> +static struct pci_dev *sbdf_to_pci(struct cxl_prot_error_info *err_info)
> +{
> + unsigned int devfn = PCI_DEVFN(err_info->device,
> + err_info->function);
> + struct pci_dev *pdev __free(pci_dev_put) =
> + pci_get_domain_bus_and_slot(err_info->segment,
> + err_info->bus,
> + devfn);
> + return pdev;
> +}
> +
> +static void cxl_handle_prot_error(struct cxl_prot_error_info *err_info)
> +{
> + struct pci_dev *pdev __free(pci_dev_put) = pci_dev_get(sbdf_to_pci(err_info));
> +
> + if (!pdev) {
> + pr_err("Failed to find the CXL device\n");
Nit: Maybe including BDF value is more informative.
> + return;
> + }
> +
> + /*
> + * Internal errors of an RCEC indicate an AER error in an
> + * RCH's downstream port. Check and handle them in the CXL.mem
> + * device driver.
> + */
> + if (pci_pcie_type(pdev) == PCI_EXP_TYPE_RC_EC)
> + return pcie_walk_rcec(pdev, cxl_rch_handle_error_iter, err_info);
> +
> + if (err_info->severity == AER_CORRECTABLE) {
> + int aer = pdev->aer_cap;
> + struct cxl_dev_state *cxlds = pci_get_drvdata(pdev);
> + struct device *dev __free(put_device) = get_device(&cxlds->cxlmd->dev);
> +
> + if (aer)
> + pci_clear_and_set_config_dword(pdev,
> + aer + PCI_ERR_COR_STATUS,
> + 0, PCI_ERR_COR_INTERNAL);
> +
> + cxl_cor_error_detected(pdev);
> +
> + pcie_clear_device_status(pdev);
> + } else {
> + cxl_do_recovery(pdev);
> + }
> +}
> +
> static void cxl_prot_err_work_fn(struct work_struct *work)
> {
> + struct cxl_prot_err_work_data wd;
> +
> + while (cxl_prot_err_kfifo_get(&wd)) {
> + struct cxl_prot_error_info *err_info = &wd.err_info;
> +
> + cxl_handle_prot_error(err_info);
> + }
> }
>
> #else
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index e77d5b53c0ce..524ac32b744a 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -2328,6 +2328,7 @@ void pcie_clear_device_status(struct pci_dev *dev)
> pcie_capability_read_word(dev, PCI_EXP_DEVSTA, &sta);
> pcie_capability_write_word(dev, PCI_EXP_DEVSTA, sta);
> }
> +EXPORT_SYMBOL_NS_GPL(pcie_clear_device_status, "CXL");
> #endif
>
> /**
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> index d6296500b004..3c54a5ed803e 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -649,16 +649,10 @@ static inline bool pci_dpc_recovered(struct pci_dev *pdev) { return false; }
> void pci_rcec_init(struct pci_dev *dev);
> void pci_rcec_exit(struct pci_dev *dev);
> void pcie_link_rcec(struct pci_dev *rcec);
> -void pcie_walk_rcec(struct pci_dev *rcec,
> - int (*cb)(struct pci_dev *, void *),
> - void *userdata);
> #else
> static inline void pci_rcec_init(struct pci_dev *dev) { }
> static inline void pci_rcec_exit(struct pci_dev *dev) { }
> static inline void pcie_link_rcec(struct pci_dev *rcec) { }
> -static inline void pcie_walk_rcec(struct pci_dev *rcec,
> - int (*cb)(struct pci_dev *, void *),
> - void *userdata) { }
> #endif
>
> #ifdef CONFIG_PCI_ATS
> @@ -967,7 +961,6 @@ void pci_no_aer(void);
> void pci_aer_init(struct pci_dev *dev);
> void pci_aer_exit(struct pci_dev *dev);
> extern const struct attribute_group aer_stats_attr_group;
> -void pci_aer_clear_fatal_status(struct pci_dev *dev);
> int pci_aer_clear_status(struct pci_dev *dev);
> int pci_aer_raw_clear_status(struct pci_dev *dev);
> void pci_save_aer_state(struct pci_dev *dev);
> @@ -976,7 +969,6 @@ void pci_restore_aer_state(struct pci_dev *dev);
> static inline void pci_no_aer(void) { }
> static inline void pci_aer_init(struct pci_dev *d) { }
> static inline void pci_aer_exit(struct pci_dev *d) { }
> -static inline void pci_aer_clear_fatal_status(struct pci_dev *dev) { }
> static inline int pci_aer_clear_status(struct pci_dev *dev) { return -EINVAL; }
> static inline int pci_aer_raw_clear_status(struct pci_dev *dev) { return -EINVAL; }
> static inline void pci_save_aer_state(struct pci_dev *dev) { }
> diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
> index 5350fa5be784..6e88331c6303 100644
> --- a/drivers/pci/pcie/aer.c
> +++ b/drivers/pci/pcie/aer.c
> @@ -290,6 +290,7 @@ void pci_aer_clear_fatal_status(struct pci_dev *dev)
> if (status)
> pci_write_config_dword(dev, aer + PCI_ERR_UNCOR_STATUS, status);
> }
> +EXPORT_SYMBOL_GPL(pci_aer_clear_fatal_status);
>
> /**
> * pci_aer_raw_clear_status - Clear AER error registers.
> diff --git a/drivers/pci/pcie/rcec.c b/drivers/pci/pcie/rcec.c
> index d0bcd141ac9c..fb6cf6449a1d 100644
> --- a/drivers/pci/pcie/rcec.c
> +++ b/drivers/pci/pcie/rcec.c
> @@ -145,6 +145,7 @@ void pcie_walk_rcec(struct pci_dev *rcec, int (*cb)(struct pci_dev *, void *),
>
> walk_rcec(walk_rcec_helper, &rcec_data);
> }
> +EXPORT_SYMBOL_NS_GPL(pcie_walk_rcec, "CXL");
>
> void pci_rcec_init(struct pci_dev *dev)
> {
> diff --git a/include/linux/aer.h b/include/linux/aer.h
> index 550407240ab5..c9a18eca16f8 100644
> --- a/include/linux/aer.h
> +++ b/include/linux/aer.h
> @@ -77,12 +77,14 @@ struct cxl_prot_err_work_data {
>
> #if defined(CONFIG_PCIEAER)
> int pci_aer_clear_nonfatal_status(struct pci_dev *dev);
> +void pci_aer_clear_fatal_status(struct pci_dev *dev);
> int pcie_aer_is_native(struct pci_dev *dev);
> #else
> static inline int pci_aer_clear_nonfatal_status(struct pci_dev *dev)
> {
> return -EINVAL;
> }
> +static inline void pci_aer_clear_fatal_status(struct pci_dev *dev) { }
> static inline int pcie_aer_is_native(struct pci_dev *dev) { return 0; }
> #endif
>
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index bff3009f9ff0..cd53715d53f3 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1806,6 +1806,9 @@ extern bool pcie_ports_native;
>
> int pcie_set_target_speed(struct pci_dev *port, enum pci_bus_speed speed_req,
> bool use_lt);
> +void pcie_walk_rcec(struct pci_dev *rcec,
> + int (*cb)(struct pci_dev *, void *),
> + void *userdata);
> #else
> #define pcie_ports_disabled true
> #define pcie_ports_native false
> @@ -1816,8 +1819,15 @@ static inline int pcie_set_target_speed(struct pci_dev *port,
> {
> return -EOPNOTSUPP;
> }
> +
> +static inline void pcie_walk_rcec(struct pci_dev *rcec,
> + int (*cb)(struct pci_dev *, void *),
> + void *userdata) { }
> +
> #endif
>
> +void pcie_clear_device_status(struct pci_dev *dev);
> +
> #define PCIE_LINK_STATE_L0S (BIT(0) | BIT(1)) /* Upstr/dwnstr L0s */
> #define PCIE_LINK_STATE_L1 BIT(2) /* L1 state */
> #define PCIE_LINK_STATE_L1_1 BIT(3) /* ASPM L1.1 state */
--
Sathyanarayanan Kuppuswamy
Linux Kernel Developer
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