On 6/5/2025 7:27 PM, Dave Jiang wrote:
>
> On 6/3/25 10:22 AM, Terry Bowman wrote:
>> CXL error handling will soon be moved from the AER driver into the CXL
>> driver. This requires a notification mechanism for the AER driver to share
>> the AER interrupt with the CXL driver. The notification will be used
>> as an indication for the CXL drivers to handle and log the CXL RAS errors.
>>
>> Add a kfifo work queue to be used by the AER driver and CXL driver. The AER
>> driver will be the sole kfifo producer adding work and the cxl_core will be
>> the sole kfifo consumer removing work. Add the boilerplate kfifo support.
>>
>> Add CXL work queue handler registration functions in the AER driver. Export
>> the functions allowing CXL driver to access. Implement registration
>> functions for the CXL driver to assign or clear the work handler function.
>>
>> Introduce function cxl_create_prot_err_info() and 'struct cxl_prot_err_info'.
>> Implement cxl_create_prot_err_info() to populate a 'struct cxl_prot_err_info'
>> instance with the AER severity and the erring device's PCI SBDF. The SBDF
>> details will be used to rediscover the erring device after the CXL driver
>> dequeues the kfifo work. The device rediscovery will be introduced along
>> with the CXL handling in future patches.
>>
>> Signed-off-by: Terry Bowman <terry.bowman@xxxxxxx>
>> ---
>> drivers/cxl/core/ras.c | 31 +++++++++-
>> drivers/cxl/cxlpci.h | 1 +
>> drivers/pci/pcie/aer.c | 132 ++++++++++++++++++++++++++++-------------
>> include/linux/aer.h | 36 +++++++++++
>> 4 files changed, 157 insertions(+), 43 deletions(-)
>>
>> diff --git a/drivers/cxl/core/ras.c b/drivers/cxl/core/ras.c
>> index 485a831695c7..d35525e79e04 100644
>> --- a/drivers/cxl/core/ras.c
>> +++ b/drivers/cxl/core/ras.c
>> @@ -5,6 +5,7 @@
>> #include <linux/aer.h>
>> #include <cxl/event.h>
>> #include <cxlmem.h>
>> +#include <cxlpci.h>
>> #include "trace.h"
>>
>> static void cxl_cper_trace_corr_port_prot_err(struct pci_dev *pdev,
>> @@ -107,13 +108,41 @@ static void cxl_cper_prot_err_work_fn(struct work_struct *work)
>> }
>> static DECLARE_WORK(cxl_cper_prot_err_work, cxl_cper_prot_err_work_fn);
>>
>> +#ifdef CONFIG_PCIEAER_CXL
>> +
>> +static void cxl_prot_err_work_fn(struct work_struct *work)
>> +{
>> +}
>> +
>> +#else
>> +static void cxl_prot_err_work_fn(struct work_struct *work) { }
>> +#endif /* CONFIG_PCIEAER_CXL */
> I wonder instead of the ifdef block we can just do:
>
> static void cxl_prot_err_work_fn(...)
> {
> if (!IS_ENABLED(CONFIG_PCIEAER_CXL))
> return;
>
> ....
> }
I have a TODO request from Jonathan Cameron in the previous series iteration to address the
same #ifdef cleanup. Jonathan recommended introducing drivers/cxl/core/aer.c and moving the
CXL related AER logic to the new file. Are you OK with that solution?
> In general we want to avoid ifdefs in C files.
>
> Also, where is CONFIG_PCIEAER_CXL defined? I'm having trouble finding the Kconfig that declares it.
>
> $ git grep CONFIG_PCIEAER_CXL
> drivers/cxl/core/pci.c:#ifdef CONFIG_PCIEAER_CXL
> drivers/cxl/core/ras.c:#ifdef CONFIG_PCIEAER_CXL
> drivers/cxl/core/ras.c:#endif /* CONFIG_PCIEAER_CXL */
> drivers/cxl/cxl.h:#ifdef CONFIG_PCIEAER_CXL
> drivers/cxl/port.c:#ifdef CONFIG_PCIEAER_CXL
> drivers/cxl/port.c:#endif /* CONFIG_PCIEAER_CXL */
> drivers/pci/pcie/aer.c:#if defined(CONFIG_PCIEAER_CXL)
> drivers/pci/pcie/aer.c:#ifdef CONFIG_PCIEAER_CXL
> drivers/pci/pcie/aer.c:#if defined(CONFIG_PCIEAER_CXL)
> include/linux/aer.h:#if defined(CONFIG_PCIEAER_CXL)
>
CONFIG_PCIEAER_CXL is a Kconfig dependent on CONFIG_PCIEAER. When enabled the
#define is found in include/generated/autoconf.h
>> +
>> +static struct work_struct cxl_prot_err_work;
>> +static DECLARE_WORK(cxl_prot_err_work, cxl_prot_err_work_fn);
>> +
>> int cxl_ras_init(void)
>> {
>> - return cxl_cper_register_prot_err_work(&cxl_cper_prot_err_work);
>> + int rc;
>> +
>> + rc = cxl_cper_register_prot_err_work(&cxl_cper_prot_err_work);
>> + if (rc)
>> + pr_err("Failed to register CPER AER kfifo (%x)", rc);
>> +
>> + rc = cxl_register_prot_err_work(&cxl_prot_err_work);
>> + if (rc) {
>> + pr_err("Failed to register native AER kfifo (%x)", rc);
>> + return rc;
>> + }
>> +
>> + return 0;
>> }
>>
>> void cxl_ras_exit(void)
>> {
>> cxl_cper_unregister_prot_err_work(&cxl_cper_prot_err_work);
>> cancel_work_sync(&cxl_cper_prot_err_work);
>> +
>> + cxl_unregister_prot_err_work();
>> + cancel_work_sync(&cxl_prot_err_work);
>> }
>> diff --git a/drivers/cxl/cxlpci.h b/drivers/cxl/cxlpci.h
>> index 54e219b0049e..6f1396ef7b77 100644
>> --- a/drivers/cxl/cxlpci.h
>> +++ b/drivers/cxl/cxlpci.h
>> @@ -4,6 +4,7 @@
>> #define __CXL_PCI_H__
>> #include <linux/pci.h>
>> #include "cxl.h"
>> +#include "linux/aer.h"
>>
>> #define CXL_MEMORY_PROGIF 0x10
>>
>> diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
>> index adb4b1123b9b..5350fa5be784 100644
>> --- a/drivers/pci/pcie/aer.c
>> +++ b/drivers/pci/pcie/aer.c
>> @@ -114,6 +114,14 @@ struct aer_stats {
>> static int pcie_aer_disable;
>> static pci_ers_result_t aer_root_reset(struct pci_dev *dev);
>>
>> +#if defined(CONFIG_PCIEAER_CXL)
> Would it make sense to move all the CXL bits to a cxl_aer.c instead of all the ifdefs in this C file?
>
> DJ
Yes, this is a good idea. I'll make the AER driver related change to separate the CXL logic.
Terry
>> +#define CXL_ERROR_SOURCES_MAX 128
>> +static DEFINE_KFIFO(cxl_prot_err_fifo, struct cxl_prot_err_work_data,
>> + CXL_ERROR_SOURCES_MAX);
>> +static DEFINE_SPINLOCK(cxl_prot_err_fifo_lock);
>> +struct work_struct *cxl_prot_err_work;
>> +#endif
>> +
>> void pci_no_aer(void)
>> {
>> pcie_aer_disable = 1;
>> @@ -1004,45 +1012,17 @@ static bool is_internal_error(struct aer_err_info *info)
>> return info->status & PCI_ERR_UNC_INTN;
>> }
>>
>> -static int cxl_rch_handle_error_iter(struct pci_dev *dev, void *data)
>> +static bool is_cxl_error(struct pci_dev *pdev, struct aer_err_info *info)
>> {
>> - struct aer_err_info *info = (struct aer_err_info *)data;
>> - const struct pci_error_handlers *err_handler;
>> + if (!info || !info->is_cxl)
>> + return false;
>>
>> - if (!is_cxl_mem_dev(dev) || !cxl_error_is_native(dev))
>> - return 0;
>> + /* Only CXL Endpoints are currently supported */
>> + if ((pci_pcie_type(pdev) != PCI_EXP_TYPE_ENDPOINT) &&
>> + (pci_pcie_type(pdev) != PCI_EXP_TYPE_RC_EC))
>> + return false;
>>
>> - /* Protect dev->driver */
>> - device_lock(&dev->dev);
>> -
>> - err_handler = dev->driver ? dev->driver->err_handler : NULL;
>> - if (!err_handler)
>> - goto out;
>> -
>> - if (info->severity == AER_CORRECTABLE) {
>> - if (err_handler->cor_error_detected)
>> - err_handler->cor_error_detected(dev);
>> - } else if (err_handler->error_detected) {
>> - if (info->severity == AER_NONFATAL)
>> - err_handler->error_detected(dev, pci_channel_io_normal);
>> - else if (info->severity == AER_FATAL)
>> - err_handler->error_detected(dev, pci_channel_io_frozen);
>> - }
>> -out:
>> - device_unlock(&dev->dev);
>> - return 0;
>> -}
>> -
>> -static void cxl_rch_handle_error(struct pci_dev *dev, struct aer_err_info *info)
>> -{
>> - /*
>> - * 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(dev) == PCI_EXP_TYPE_RC_EC &&
>> - is_internal_error(info))
>> - pcie_walk_rcec(dev, cxl_rch_handle_error_iter, info);
>> + return is_internal_error(info);
>> }
>>
>> static int handles_cxl_error_iter(struct pci_dev *dev, void *data)
>> @@ -1056,13 +1036,17 @@ static int handles_cxl_error_iter(struct pci_dev *dev, void *data)
>> return *handles_cxl;
>> }
>>
>> -static bool handles_cxl_errors(struct pci_dev *rcec)
>> +static bool handles_cxl_errors(struct pci_dev *dev)
>> {
>> bool handles_cxl = false;
>>
>> - if (pci_pcie_type(rcec) == PCI_EXP_TYPE_RC_EC &&
>> - pcie_aer_is_native(rcec))
>> - pcie_walk_rcec(rcec, handles_cxl_error_iter, &handles_cxl);
>> + if (!pcie_aer_is_native(dev))
>> + return false;
>> +
>> + if (pci_pcie_type(dev) == PCI_EXP_TYPE_RC_EC)
>> + pcie_walk_rcec(dev, handles_cxl_error_iter, &handles_cxl);
>> + else
>> + handles_cxl = pcie_is_cxl(dev);
>>
>> return handles_cxl;
>> }
>> @@ -1076,10 +1060,46 @@ static void cxl_rch_enable_rcec(struct pci_dev *rcec)
>> pci_info(rcec, "CXL: Internal errors unmasked");
>> }
>>
>> +static int cxl_create_prot_error_info(struct pci_dev *pdev,
>> + struct aer_err_info *aer_err_info,
>> + struct cxl_prot_error_info *cxl_err_info)
>> +{
>> + cxl_err_info->severity = aer_err_info->severity;
>> +
>> + cxl_err_info->function = PCI_FUNC(pdev->devfn);
>> + cxl_err_info->device = PCI_SLOT(pdev->devfn);
>> + cxl_err_info->bus = pdev->bus->number;
>> + cxl_err_info->segment = pci_domain_nr(pdev->bus);
>> +
>> + return 0;
>> +}
>> +
>> +static void forward_cxl_error(struct pci_dev *pdev, struct aer_err_info *aer_err_info)
>> +{
>> + struct cxl_prot_err_work_data wd;
>> + struct cxl_prot_error_info *cxl_err_info = &wd.err_info;
>> +
>> + cxl_create_prot_error_info(pdev, aer_err_info, cxl_err_info);
>> +
>> + if (!kfifo_put(&cxl_prot_err_fifo, wd)) {
>> + dev_err_ratelimited(&pdev->dev, "CXL kfifo overflow\n");
>> + return;
>> + }
>> +
>> + schedule_work(cxl_prot_err_work);
>> +}
>> +
>> #else
>> static inline void cxl_rch_enable_rcec(struct pci_dev *dev) { }
>> static inline void cxl_rch_handle_error(struct pci_dev *dev,
>> struct aer_err_info *info) { }
>> +static inline void forward_cxl_error(struct pci_dev *dev,
>> + struct aer_err_info *info) { }
>> +static inline bool handles_cxl_errors(struct pci_dev *dev)
>> +{
>> + return false;
>> +}
>> +static bool is_cxl_error(struct pci_dev *pdev, struct aer_err_info *info) { return 0; };
>> #endif
>>
>> /**
>> @@ -1117,8 +1137,11 @@ static void pci_aer_handle_error(struct pci_dev *dev, struct aer_err_info *info)
>>
>> static void handle_error_source(struct pci_dev *dev, struct aer_err_info *info)
>> {
>> - cxl_rch_handle_error(dev, info);
>> - pci_aer_handle_error(dev, info);
>> + if (is_cxl_error(dev, info))
>> + forward_cxl_error(dev, info);
>> + else
>> + pci_aer_handle_error(dev, info);
>> +
>> pci_dev_put(dev);
>> }
>>
>> @@ -1582,6 +1605,31 @@ static pci_ers_result_t aer_root_reset(struct pci_dev *dev)
>> return rc ? PCI_ERS_RESULT_DISCONNECT : PCI_ERS_RESULT_RECOVERED;
>> }
>>
>> +#if defined(CONFIG_PCIEAER_CXL)
>> +
>> +int cxl_register_prot_err_work(struct work_struct *work)
>> +{
>> + guard(spinlock)(&cxl_prot_err_fifo_lock);
>> + cxl_prot_err_work = work;
>> + return 0;
>> +}
>> +EXPORT_SYMBOL_NS_GPL(cxl_register_prot_err_work, "CXL");
>> +
>> +int cxl_unregister_prot_err_work(void)
>> +{
>> + guard(spinlock)(&cxl_prot_err_fifo_lock);
>> + cxl_prot_err_work = NULL;
>> + return 0;
>> +}
>> +EXPORT_SYMBOL_NS_GPL(cxl_unregister_prot_err_work, "CXL");
>> +
>> +int cxl_prot_err_kfifo_get(struct cxl_prot_err_work_data *wd)
>> +{
>> + return kfifo_get(&cxl_prot_err_fifo, wd);
>> +}
>> +EXPORT_SYMBOL_NS_GPL(cxl_prot_err_kfifo_get, "CXL");
>> +#endif
>> +
>> static struct pcie_port_service_driver aerdriver = {
>> .name = "aer",
>> .port_type = PCIE_ANY_PORT,
>> diff --git a/include/linux/aer.h b/include/linux/aer.h
>> index 02940be66324..550407240ab5 100644
>> --- a/include/linux/aer.h
>> +++ b/include/linux/aer.h
>> @@ -10,6 +10,7 @@
>>
>> #include <linux/errno.h>
>> #include <linux/types.h>
>> +#include <linux/workqueue_types.h>
>>
>> #define AER_NONFATAL 0
>> #define AER_FATAL 1
>> @@ -53,6 +54,27 @@ struct aer_capability_regs {
>> u16 uncor_err_source;
>> };
>>
>> +/**
>> + * struct cxl_prot_err_info - Error information used in CXL error handling
>> + * @severity: AER severity
>> + * @function: Device's PCI function
>> + * @device: Device's PCI device
>> + * @bus: Device's PCI bus
>> + * @segment: Device's PCI segment
>> + */
>> +struct cxl_prot_error_info {
>> + int severity;
>> +
>> + u8 function;
>> + u8 device;
>> + u8 bus;
>> + u16 segment;
>> +};
>> +
>> +struct cxl_prot_err_work_data {
>> + struct cxl_prot_error_info err_info;
>> +};
>> +
>> #if defined(CONFIG_PCIEAER)
>> int pci_aer_clear_nonfatal_status(struct pci_dev *dev);
>> int pcie_aer_is_native(struct pci_dev *dev);
>> @@ -64,6 +86,20 @@ static inline int pci_aer_clear_nonfatal_status(struct pci_dev *dev)
>> static inline int pcie_aer_is_native(struct pci_dev *dev) { return 0; }
>> #endif
>>
>> +#if defined(CONFIG_PCIEAER_CXL)
>> +int cxl_register_prot_err_work(struct work_struct *work);
>> +int cxl_unregister_prot_err_work(void);
>> +int cxl_prot_err_kfifo_get(struct cxl_prot_err_work_data *wd);
>> +#else
>> +static inline int
>> +cxl_register_prot_err_work(struct work_struct *work)
>> +{
>> + return 0;
>> +}
>> +static inline int cxl_unregister_prot_err_work(void) { return 0; }
>> +static inline int cxl_prot_err_kfifo_get(struct cxl_prot_err_work_data *wd) { return 0; }
>> +#endif
>> +
>> void pci_print_aer(struct pci_dev *dev, int aer_severity,
>> struct aer_capability_regs *aer);
>> int cper_severity_to_aer(int cper_severity);
