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Message-ID: <21623130-2ef8-4420-8282-3c33f5203e1a@intel.com>
Date: Wed, 14 Jan 2026 13:35:42 -0700
From: Dave Jiang <dave.jiang@...el.com>
To: Terry Bowman <terry.bowman@....com>, dave@...olabs.net,
jonathan.cameron@...wei.com, alison.schofield@...el.com,
dan.j.williams@...el.com, bhelgaas@...gle.com, shiju.jose@...wei.com,
ming.li@...omail.com, Smita.KoralahalliChannabasappa@....com,
rrichter@....com, dan.carpenter@...aro.org,
PradeepVineshReddy.Kodamati@....com, lukas@...ner.de,
Benjamin.Cheatham@....com, sathyanarayanan.kuppuswamy@...ux.intel.com,
linux-cxl@...r.kernel.org, vishal.l.verma@...el.com, alucerop@....com,
ira.weiny@...el.com
Cc: linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org
Subject: Re: [PATCH v14 08/34] cxl/pci: Move CXL driver's RCH error handling
into core/ras_rch.c
On 1/14/26 11:20 AM, Terry Bowman wrote:
> Restricted CXL Host (RCH) protocol error handling uses a procedure distinct
> from the CXL Virtual Hierarchy (VH) handling. This is because of the
> differences in the RCH and VH topologies. Improve the maintainability and
> add ability to enable/disable RCH handling.
>
> Move and combine the RCH handling code into a single block conditionally
> compiled with the CONFIG_CXL_RCH_RAS kernel config.
>
> Signed-off-by: Terry Bowman <terry.bowman@....com>
> Reviewed-by: Jonathan Cameron <jonathan.cameron@...wei.com>
> Signed-off-by: Dan Williams <dan.j.williams@...el.com>
>
Reviewed-by: Dave Jiang <dave.jiang@...el.com>
> ---
>
> Changes in v13->v14:
> - Add sign-off for Dan and Jonathan
> - Revert inadvertent formatting of cxl_dport_map_rch_aer() (Jonathan)
> - Remove default value for CXL_RCH_RAS (Dan)
> - Remove unnecessary pci.h include in core.h & ras_rch.c (Jonathan)
> - Add linux/types.h include in ras_rch.c (Jonathan)
> - Change CONFIG_CXL_RCH_RAS -> CONFIG_CXL_RAS (Dan)
>
> Changes in v12->v13:
> - None
>
> Changes v11->v12:
> - Moved CXL_RCH_RAS Kconfig definition here from following commit.
>
> Changes v10->v11:
> - New patch
> ---
> drivers/cxl/core/Makefile | 1 +
> drivers/cxl/core/core.h | 11 +---
> drivers/cxl/core/pci.c | 115 -----------------------------------
> drivers/cxl/core/ras_rch.c | 121 +++++++++++++++++++++++++++++++++++++
> tools/testing/cxl/Kbuild | 1 +
> 5 files changed, 126 insertions(+), 123 deletions(-)
> create mode 100644 drivers/cxl/core/ras_rch.c
>
> diff --git a/drivers/cxl/core/Makefile b/drivers/cxl/core/Makefile
> index b2930cc54f8b..b37f38d502d8 100644
> --- a/drivers/cxl/core/Makefile
> +++ b/drivers/cxl/core/Makefile
> @@ -20,3 +20,4 @@ cxl_core-$(CONFIG_CXL_MCE) += mce.o
> cxl_core-$(CONFIG_CXL_FEATURES) += features.o
> cxl_core-$(CONFIG_CXL_EDAC_MEM_FEATURES) += edac.o
> cxl_core-$(CONFIG_CXL_RAS) += ras.o
> +cxl_core-$(CONFIG_CXL_RAS) += ras_rch.o
> diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
> index bc818de87ccc..724361195057 100644
> --- a/drivers/cxl/core/core.h
> +++ b/drivers/cxl/core/core.h
> @@ -149,6 +149,9 @@ int cxl_ras_init(void);
> void cxl_ras_exit(void);
> bool cxl_handle_ras(struct cxl_dev_state *cxlds, void __iomem *ras_base);
> void cxl_handle_cor_ras(struct cxl_dev_state *cxlds, void __iomem *ras_base);
> +void cxl_dport_map_rch_aer(struct cxl_dport *dport);
> +void cxl_disable_rch_root_ints(struct cxl_dport *dport);
> +void cxl_handle_rdport_errors(struct cxl_dev_state *cxlds);
> #else
> static inline int cxl_ras_init(void)
> {
> @@ -164,14 +167,6 @@ static inline bool cxl_handle_ras(struct cxl_dev_state *cxlds, void __iomem *ras
> return false;
> }
> static inline void cxl_handle_cor_ras(struct cxl_dev_state *cxlds, void __iomem *ras_base) { }
> -#endif /* CONFIG_CXL_RAS */
> -
> -/* Restricted CXL Host specific RAS functions */
> -#ifdef CONFIG_CXL_RAS
> -void cxl_dport_map_rch_aer(struct cxl_dport *dport);
> -void cxl_disable_rch_root_ints(struct cxl_dport *dport);
> -void cxl_handle_rdport_errors(struct cxl_dev_state *cxlds);
> -#else
> static inline void cxl_dport_map_rch_aer(struct cxl_dport *dport) { }
> static inline void cxl_disable_rch_root_ints(struct cxl_dport *dport) { }
> static inline void cxl_handle_rdport_errors(struct cxl_dev_state *cxlds) { }
> diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c
> index e132fff80979..b838c59d7a3c 100644
> --- a/drivers/cxl/core/pci.c
> +++ b/drivers/cxl/core/pci.c
> @@ -632,121 +632,6 @@ void read_cdat_data(struct cxl_port *port)
> }
> EXPORT_SYMBOL_NS_GPL(read_cdat_data, "CXL");
>
> -#ifdef CONFIG_CXL_RAS
> -void cxl_dport_map_rch_aer(struct cxl_dport *dport)
> -{
> - resource_size_t aer_phys;
> - struct device *host;
> - u16 aer_cap;
> -
> - aer_cap = cxl_rcrb_to_aer(dport->dport_dev, dport->rcrb.base);
> - if (aer_cap) {
> - host = dport->reg_map.host;
> - aer_phys = aer_cap + dport->rcrb.base;
> - dport->regs.dport_aer = devm_cxl_iomap_block(host, aer_phys,
> - sizeof(struct aer_capability_regs));
> - }
> -}
> -
> -void cxl_disable_rch_root_ints(struct cxl_dport *dport)
> -{
> - void __iomem *aer_base = dport->regs.dport_aer;
> - u32 aer_cmd_mask, aer_cmd;
> -
> - if (!aer_base)
> - return;
> -
> - /*
> - * Disable RCH root port command interrupts.
> - * CXL 3.0 12.2.1.1 - RCH Downstream Port-detected Errors
> - *
> - * This sequence may not be necessary. CXL spec states disabling
> - * the root cmd register's interrupts is required. But, PCI spec
> - * shows these are disabled by default on reset.
> - */
> - aer_cmd_mask = (PCI_ERR_ROOT_CMD_COR_EN |
> - PCI_ERR_ROOT_CMD_NONFATAL_EN |
> - PCI_ERR_ROOT_CMD_FATAL_EN);
> - aer_cmd = readl(aer_base + PCI_ERR_ROOT_COMMAND);
> - aer_cmd &= ~aer_cmd_mask;
> - writel(aer_cmd, aer_base + PCI_ERR_ROOT_COMMAND);
> -}
> -
> -/*
> - * Copy the AER capability registers using 32 bit read accesses.
> - * This is necessary because RCRB AER capability is MMIO mapped. Clear the
> - * status after copying.
> - *
> - * @aer_base: base address of AER capability block in RCRB
> - * @aer_regs: destination for copying AER capability
> - */
> -static bool cxl_rch_get_aer_info(void __iomem *aer_base,
> - struct aer_capability_regs *aer_regs)
> -{
> - int read_cnt = sizeof(struct aer_capability_regs) / sizeof(u32);
> - u32 *aer_regs_buf = (u32 *)aer_regs;
> - int n;
> -
> - if (!aer_base)
> - return false;
> -
> - /* Use readl() to guarantee 32-bit accesses */
> - for (n = 0; n < read_cnt; n++)
> - aer_regs_buf[n] = readl(aer_base + n * sizeof(u32));
> -
> - writel(aer_regs->uncor_status, aer_base + PCI_ERR_UNCOR_STATUS);
> - writel(aer_regs->cor_status, aer_base + PCI_ERR_COR_STATUS);
> -
> - return true;
> -}
> -
> -/* Get AER severity. Return false if there is no error. */
> -static bool cxl_rch_get_aer_severity(struct aer_capability_regs *aer_regs,
> - int *severity)
> -{
> - if (aer_regs->uncor_status & ~aer_regs->uncor_mask) {
> - if (aer_regs->uncor_status & PCI_ERR_ROOT_FATAL_RCV)
> - *severity = AER_FATAL;
> - else
> - *severity = AER_NONFATAL;
> - return true;
> - }
> -
> - if (aer_regs->cor_status & ~aer_regs->cor_mask) {
> - *severity = AER_CORRECTABLE;
> - return true;
> - }
> -
> - return false;
> -}
> -
> -void cxl_handle_rdport_errors(struct cxl_dev_state *cxlds)
> -{
> - struct pci_dev *pdev = to_pci_dev(cxlds->dev);
> - struct aer_capability_regs aer_regs;
> - struct cxl_dport *dport;
> - int severity;
> -
> - struct cxl_port *port __free(put_cxl_port) =
> - cxl_pci_find_port(pdev, &dport);
> - if (!port)
> - return;
> -
> - if (!cxl_rch_get_aer_info(dport->regs.dport_aer, &aer_regs))
> - return;
> -
> - if (!cxl_rch_get_aer_severity(&aer_regs, &severity))
> - return;
> -
> - pci_print_aer(pdev, severity, &aer_regs);
> -
> - if (severity == AER_CORRECTABLE)
> - cxl_handle_cor_ras(cxlds, dport->regs.ras);
> - else
> - cxl_handle_ras(cxlds, dport->regs.ras);
> -}
> -#endif
> -
> static int cxl_flit_size(struct pci_dev *pdev)
> {
> if (cxl_pci_flit_256(pdev))
> diff --git a/drivers/cxl/core/ras_rch.c b/drivers/cxl/core/ras_rch.c
> new file mode 100644
> index 000000000000..ed58afd18ecc
> --- /dev/null
> +++ b/drivers/cxl/core/ras_rch.c
> @@ -0,0 +1,121 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/* Copyright(c) 2025 AMD Corporation. All rights reserved. */
> +
> +#include <linux/types.h>
> +#include <linux/aer.h>
> +#include "cxl.h"
> +#include "core.h"
> +#include "cxlmem.h"
> +
> +void cxl_dport_map_rch_aer(struct cxl_dport *dport)
> +{
> + resource_size_t aer_phys;
> + struct device *host;
> + u16 aer_cap;
> +
> + aer_cap = cxl_rcrb_to_aer(dport->dport_dev, dport->rcrb.base);
> + if (aer_cap) {
> + host = dport->reg_map.host;
> + aer_phys = aer_cap + dport->rcrb.base;
> + dport->regs.dport_aer =
> + devm_cxl_iomap_block(host, aer_phys,
> + sizeof(struct aer_capability_regs));
> + }
> +}
> +
> +void cxl_disable_rch_root_ints(struct cxl_dport *dport)
> +{
> + void __iomem *aer_base = dport->regs.dport_aer;
> + u32 aer_cmd_mask, aer_cmd;
> +
> + if (!aer_base)
> + return;
> +
> + /*
> + * Disable RCH root port command interrupts.
> + * CXL 3.0 12.2.1.1 - RCH Downstream Port-detected Errors
> + *
> + * This sequence may not be necessary. CXL spec states disabling
> + * the root cmd register's interrupts is required. But, PCI spec
> + * shows these are disabled by default on reset.
> + */
> + aer_cmd_mask = (PCI_ERR_ROOT_CMD_COR_EN |
> + PCI_ERR_ROOT_CMD_NONFATAL_EN |
> + PCI_ERR_ROOT_CMD_FATAL_EN);
> + aer_cmd = readl(aer_base + PCI_ERR_ROOT_COMMAND);
> + aer_cmd &= ~aer_cmd_mask;
> + writel(aer_cmd, aer_base + PCI_ERR_ROOT_COMMAND);
> +}
> +
> +/*
> + * Copy the AER capability registers using 32 bit read accesses.
> + * This is necessary because RCRB AER capability is MMIO mapped. Clear the
> + * status after copying.
> + *
> + * @aer_base: base address of AER capability block in RCRB
> + * @aer_regs: destination for copying AER capability
> + */
> +static bool cxl_rch_get_aer_info(void __iomem *aer_base,
> + struct aer_capability_regs *aer_regs)
> +{
> + int read_cnt = sizeof(struct aer_capability_regs) / sizeof(u32);
> + u32 *aer_regs_buf = (u32 *)aer_regs;
> + int n;
> +
> + if (!aer_base)
> + return false;
> +
> + /* Use readl() to guarantee 32-bit accesses */
> + for (n = 0; n < read_cnt; n++)
> + aer_regs_buf[n] = readl(aer_base + n * sizeof(u32));
> +
> + writel(aer_regs->uncor_status, aer_base + PCI_ERR_UNCOR_STATUS);
> + writel(aer_regs->cor_status, aer_base + PCI_ERR_COR_STATUS);
> +
> + return true;
> +}
> +
> +/* Get AER severity. Return false if there is no error. */
> +static bool cxl_rch_get_aer_severity(struct aer_capability_regs *aer_regs,
> + int *severity)
> +{
> + if (aer_regs->uncor_status & ~aer_regs->uncor_mask) {
> + if (aer_regs->uncor_status & PCI_ERR_ROOT_FATAL_RCV)
> + *severity = AER_FATAL;
> + else
> + *severity = AER_NONFATAL;
> + return true;
> + }
> +
> + if (aer_regs->cor_status & ~aer_regs->cor_mask) {
> + *severity = AER_CORRECTABLE;
> + return true;
> + }
> +
> + return false;
> +}
> +
> +void cxl_handle_rdport_errors(struct cxl_dev_state *cxlds)
> +{
> + struct pci_dev *pdev = to_pci_dev(cxlds->dev);
> + struct aer_capability_regs aer_regs;
> + struct cxl_dport *dport;
> + int severity;
> +
> + struct cxl_port *port __free(put_cxl_port) =
> + cxl_pci_find_port(pdev, &dport);
> + if (!port)
> + return;
> +
> + if (!cxl_rch_get_aer_info(dport->regs.dport_aer, &aer_regs))
> + return;
> +
> + if (!cxl_rch_get_aer_severity(&aer_regs, &severity))
> + return;
> +
> + pci_print_aer(pdev, severity, &aer_regs);
> + if (severity == AER_CORRECTABLE)
> + cxl_handle_cor_ras(cxlds, dport->regs.ras);
> + else
> + cxl_handle_ras(cxlds, dport->regs.ras);
> +}
> diff --git a/tools/testing/cxl/Kbuild b/tools/testing/cxl/Kbuild
> index b7ea66382f3b..6eceefefb0e0 100644
> --- a/tools/testing/cxl/Kbuild
> +++ b/tools/testing/cxl/Kbuild
> @@ -63,6 +63,7 @@ cxl_core-$(CONFIG_CXL_MCE) += $(CXL_CORE_SRC)/mce.o
> cxl_core-$(CONFIG_CXL_FEATURES) += $(CXL_CORE_SRC)/features.o
> cxl_core-$(CONFIG_CXL_EDAC_MEM_FEATURES) += $(CXL_CORE_SRC)/edac.o
> cxl_core-$(CONFIG_CXL_RAS) += $(CXL_CORE_SRC)/ras.o
> +cxl_core-$(CONFIG_CXL_RAS) += $(CXL_CORE_SRC)/ras_rch.o
> cxl_core-y += config_check.o
> cxl_core-y += cxl_core_test.o
> cxl_core-y += cxl_core_exports.o
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