Re: [PATCH v11 06/23] CXL/AER: Introduce rch_aer.c into AER driver for handling CXL RCH errors

Dave Jiang
2025-08-28T20:53:51Z

On 8/26/25 6:35 PM, Terry Bowman wrote:
> The restricted CXL Host (RCH) AER error handling logic currently resides
> in the AER driver file, drivers/pci/pcie/aer.c. CXL specific changes are
> conditionally compiled using #ifdefs.
>
> Improve the AER driver maintainability by separating the RCH specific logic
> from the AER driver's core functionality and removing the ifdefs. Introduce
> drivers/pci/pcie/rch_aer.c for moving the RCH AER logic into.
>
> Move the CXL logic into the new file but leave helper functions in aer.c
> for now as they will be moved in future patch for CXL virtual hierarchy
> handling.
>
> 2 changes are required to maintain compilation after the move. Change
> cxl_rch_handle_error() & cxl_rch_enable_rcec() to be non-static inorder for
> accessing from the AER driver in aer.c.
>
> Introduce CONFIG_CXL_RCH_RAS in cxl/Kconfig. Update pcie/pcie/Makefile to
> conditionally compile rch_aer.c file using CONFIG_CXL_RCH_RAS.
>
> Signed-off-by: Terry Bowman <terry.bowman@amd.com>
>
> ---
> Changes in v10->v11:
> - Remove changes in code-split and move to earlier, new patch
> - Add #include <linux/bitfield.h> to cxl_ras.c
> - Move cxl_rch_handle_error() & cxl_rch_enable_rcec() declarations from pci.h
> to aer.h, more localized.
> - Introduce CONFIG_CXL_RCH_RAS, includes Makefile changes, ras.c ifdef changes
> ---
> drivers/cxl/Kconfig | 9 +++-
> drivers/cxl/core/ras.c | 3 ++
> drivers/pci/pci.h | 20 +++++++
> drivers/pci/pcie/Makefile | 1 +
> drivers/pci/pcie/aer.c | 108 +++----------------------------------
> drivers/pci/pcie/rch_aer.c | 99 ++++++++++++++++++++++++++++++++++

I wonder if this should be cxl_rch_aer.c to be clear that it's cxl related code.

DJ

> 6 files changed, 138 insertions(+), 102 deletions(-)
> create mode 100644 drivers/pci/pcie/rch_aer.c
>
> diff --git a/drivers/cxl/Kconfig b/drivers/cxl/Kconfig
> index 1c7c8989fd8b..028201e24523 100644
> --- a/drivers/cxl/Kconfig
> +++ b/drivers/cxl/Kconfig
> @@ -235,5 +235,12 @@ config CXL_MCE
>
> config CXL_RAS
> def_bool y
> - depends on ACPI_APEI_GHES && PCIEAER_CXL
> + depends on ACPI_APEI_GHES && PCIEAER && CXL_PCI
> +
> +config CXL_RCH_RAS
> + bool "CXL: Restricted CXL Host (RCH) protocol error handling"
> + def_bool n
> + depends on CXL_RAS
> + help
> + RAS support for Restricted CXL Host (RCH) defined in CXL1.1.
> endif
> diff --git a/drivers/cxl/core/ras.c b/drivers/cxl/core/ras.c
> index f42f9a255ef8..c9f2f0335bfd 100644
> --- a/drivers/cxl/core/ras.c
> +++ b/drivers/cxl/core/ras.c
> @@ -126,6 +126,9 @@ void cxl_ras_exit(void)
> cancel_work_sync(&cxl_cper_prot_err_work);
> }
>
> +static bool cxl_handle_ras(struct cxl_dev_state *cxlds, void __iomem *ras_base);
> +static void cxl_handle_cor_ras(struct cxl_dev_state *cxlds, void __iomem *ras_base);
> +
> #ifdef CONFIG_CXL_RCH_RAS
> static void cxl_dport_map_rch_aer(struct cxl_dport *dport)
> {
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> index 12215ee72afb..c8a0c0ec0073 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -1159,4 +1159,24 @@ static inline int pci_msix_write_tph_tag(struct pci_dev *pdev, unsigned int inde
> (PCI_CONF1_ADDRESS(bus, dev, func, reg) | \
> PCI_CONF1_EXT_REG(reg))
>
> +struct aer_err_info;
> +
> +#ifdef CONFIG_CXL_RCH_RAS
> +void cxl_rch_handle_error(struct pci_dev *dev, struct aer_err_info *info);
> +void cxl_rch_enable_rcec(struct pci_dev *rcec);
> +#else
> +static inline void cxl_rch_handle_error(struct pci_dev *dev, struct aer_err_info *info) { }
> +static inline void cxl_rch_enable_rcec(struct pci_dev *rcec) { }
> +#endif
> +
> +#ifdef CONFIG_CXL_RAS
> +void pci_aer_unmask_internal_errors(struct pci_dev *dev);
> +bool cxl_error_is_native(struct pci_dev *dev);
> +bool is_internal_error(struct aer_err_info *info);
> +#else
> +static inline void pci_aer_unmask_internal_errors(struct pci_dev *dev) { }
> +static inline bool cxl_error_is_native(struct pci_dev *dev) { return false; }
> +static inline bool is_internal_error(struct aer_err_info *info) { return false; }
> +#endif
> +
> #endif /* DRIVERS_PCI_H */
> diff --git a/drivers/pci/pcie/Makefile b/drivers/pci/pcie/Makefile
> index 173829aa02e6..07c299dbcdd7 100644
> --- a/drivers/pci/pcie/Makefile
> +++ b/drivers/pci/pcie/Makefile
> @@ -8,6 +8,7 @@ obj-$(CONFIG_PCIEPORTBUS) += pcieportdrv.o bwctrl.o
>
> obj-y += aspm.o
> obj-$(CONFIG_PCIEAER) += aer.o err.o tlp.o
> +obj-$(CONFIG_CXL_RCH_RAS) += rch_aer.o
> obj-$(CONFIG_PCIEAER_INJECT) += aer_inject.o
> obj-$(CONFIG_PCIE_PME) += pme.o
> obj-$(CONFIG_PCIE_DPC) += dpc.o
> diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
> index 7fe9f883f5c5..29de7ee861f7 100644
> --- a/drivers/pci/pcie/aer.c
> +++ b/drivers/pci/pcie/aer.c
> @@ -1098,7 +1098,7 @@ static bool find_source_device(struct pci_dev *parent,
> * Note: AER must be enabled and supported by the device which must be
> * checked in advance, e.g. with pcie_aer_is_native().
> */
> -static void pci_aer_unmask_internal_errors(struct pci_dev *dev)
> +void pci_aer_unmask_internal_errors(struct pci_dev *dev)
> {
> int aer = dev->aer_cap;
> u32 mask;
> @@ -1111,119 +1111,25 @@ static void pci_aer_unmask_internal_errors(struct pci_dev *dev)
> mask &= ~PCI_ERR_COR_INTERNAL;
> pci_write_config_dword(dev, aer + PCI_ERR_COR_MASK, mask);
> }
> +EXPORT_SYMBOL_NS_GPL(pci_aer_unmask_internal_errors, "CXL");
>
> -static bool is_cxl_mem_dev(struct pci_dev *dev)
> -{
> - /*
> - * 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).
> - */
> - if (dev->devfn != PCI_DEVFN(0, 0))
> - return false;
> -
> - /*
> - * CXL Memory Devices must have the 502h class code set (CXL
> - * 3.0, 8.1.12.1).
> - */
> - if ((dev->class >> 8) != PCI_CLASS_MEMORY_CXL)
> - return false;
> -
> - return true;
> -}
> -
> -static bool cxl_error_is_native(struct pci_dev *dev)
> +bool cxl_error_is_native(struct pci_dev *dev)
> {
> struct pci_host_bridge *host = pci_find_host_bridge(dev->bus);
>
> return (pcie_ports_native || host->native_aer);
> }
> +EXPORT_SYMBOL_NS_GPL(cxl_error_is_native, "CXL");
>
> -static bool is_internal_error(struct aer_err_info *info)
> +bool is_internal_error(struct aer_err_info *info)
> {
> if (info->severity == AER_CORRECTABLE)
> return info->status & PCI_ERR_COR_INTERNAL;
>
> return info->status & PCI_ERR_UNC_INTN;
> }
> -
> -static int cxl_rch_handle_error_iter(struct pci_dev *dev, void *data)
> -{
> - struct aer_err_info *info = (struct aer_err_info *)data;
> - const struct pci_error_handlers *err_handler;
> -
> - if (!is_cxl_mem_dev(dev) || !cxl_error_is_native(dev))
> - return 0;
> -
> - /* 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);
> -}
> -
> -static int handles_cxl_error_iter(struct pci_dev *dev, void *data)
> -{
> - bool *handles_cxl = data;
> -
> - if (!*handles_cxl)
> - *handles_cxl = is_cxl_mem_dev(dev) && cxl_error_is_native(dev);
> -
> - /* Non-zero terminates iteration */
> - return *handles_cxl;
> -}
> -
> -static bool handles_cxl_errors(struct pci_dev *rcec)
> -{
> - 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);
> -
> - return handles_cxl;
> -}
> -
> -static void cxl_rch_enable_rcec(struct pci_dev *rcec)
> -{
> - if (!handles_cxl_errors(rcec))
> - return;
> -
> - pci_aer_unmask_internal_errors(rcec);
> - pci_info(rcec, "CXL: Internal errors unmasked");
> -}
> -
> -#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) { }
> -#endif
> +EXPORT_SYMBOL_NS_GPL(is_internal_error, "CXL");
> +#endif /* CONFIG_CXL_RAS */
>
> /**
> * pci_aer_handle_error - handle logging error into an event log
> diff --git a/drivers/pci/pcie/rch_aer.c b/drivers/pci/pcie/rch_aer.c
> new file mode 100644
> index 000000000000..bfe071eebf67
> --- /dev/null
> +++ b/drivers/pci/pcie/rch_aer.c
> @@ -0,0 +1,99 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/* Copyright(c) 2025 AMD Corporation. All rights reserved. */
> +
> +#include <linux/pci.h>
> +#include <linux/aer.h>
> +#include <linux/bitfield.h>
> +#include "../pci.h"
> +
> +static bool is_cxl_mem_dev(struct pci_dev *dev)
> +{
> + /*
> + * 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).
> + */
> + if (dev->devfn != PCI_DEVFN(0, 0))
> + return false;
> +
> + /*
> + * CXL Memory Devices must have the 502h class code set (CXL
> + * 3.0, 8.1.12.1).
> + */
> + if ((dev->class >> 8) != PCI_CLASS_MEMORY_CXL)
> + return false;
> +
> + return true;
> +}
> +
> +static int cxl_rch_handle_error_iter(struct pci_dev *dev, void *data)
> +{
> + struct aer_err_info *info = (struct aer_err_info *)data;
> + const struct pci_error_handlers *err_handler;
> +
> + if (!is_cxl_mem_dev(dev) || !cxl_error_is_native(dev))
> + return 0;
> +
> + /* 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;
> +}
> +
> +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);
> +}
> +
> +static int handles_cxl_error_iter(struct pci_dev *dev, void *data)
> +{
> + bool *handles_cxl = data;
> +
> + if (!*handles_cxl)
> + *handles_cxl = is_cxl_mem_dev(dev) && cxl_error_is_native(dev);
> +
> + /* Non-zero terminates iteration */
> + return *handles_cxl;
> +}
> +
> +static bool handles_cxl_errors(struct pci_dev *rcec)
> +{
> + 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);
> +
> + return handles_cxl;
> +}
> +
> +void cxl_rch_enable_rcec(struct pci_dev *rcec)
> +{
> + if (!handles_cxl_errors(rcec))
> + return;
> +
> + pci_aer_unmask_internal_errors(rcec);
> + pci_info(rcec, "CXL: Internal errors unmasked");
> +}