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Message-ID: <03ee0a67-9f2f-40a2-aa47-e548fb800ab9@amd.com>
Date: Fri, 3 Oct 2025 15:12:20 -0500
From: "Cheatham, Benjamin" <benjamin.cheatham@....com>
To: Terry Bowman <terry.bowman@....com>
CC: <linux-kernel@...r.kernel.org>, <linux-pci@...r.kernel.org>,
<dave@...olabs.net>, <jonathan.cameron@...wei.com>, <dave.jiang@...el.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>, <sathyanarayanan.kuppuswamy@...ux.intel.com>,
<linux-cxl@...r.kernel.org>, <alucerop@....com>, <ira.weiny@...el.com>
Subject: Re: [PATCH v12 21/25] CXL/PCI: Introduce CXL Port protocol error
handlers
On 9/25/2025 5:34 PM, Terry Bowman wrote:
> Introduce CXL error handlers for CXL Port devices.
>
> Add functions cxl_port_cor_error_detected() and cxl_port_error_detected().
> These will serve as the handlers for all CXL Port devices. Introduce
> cxl_get_ras_base() to provide the RAS base address needed by the handlers.
>
> Update cxl_handle_proto_error() to call the CXL Port or CXL Endpoint
> handler depending on which CXL device reports the error.
>
> Implement cxl_get_ras_base() to return the cached RAS register address of a
> CXL Root Port, CXL Downstream Port, or CXL Upstream Port.
>
> Introduce get_pci_cxl_host_dev() to return the host responsible for
> releasing the RAS mapped resources. CXL endpoints do not use a host to
> manage its resources, allow for NULL in the case of an EP. Use reference
> count increment on the host to prevent resource release. Make the caller
> responsible for the reference decrement.
>
> Update the AER driver's is_cxl_error() PCI type check because CXL Port
> devices are now supported.
>
> Signed-off-by: Terry Bowman <terry.bowman@....com>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
> Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
>
> ---
>
> Changes in v11->v12:
> - Add call to cxl_pci_drv_bound() in cxl_handle_proto_error() and
> pci_to_cxl_dev()
> - Change cxl_error_detected() -> cxl_cor_error_detected()
> - Remove NULL variable assignments
> - Replace bus_find_device() with find_cxl_port_by_uport() for upstream
> port searches.
>
> Changes in v10->v11:
> - None
> ---
> drivers/cxl/core/core.h | 10 +++
> drivers/cxl/core/port.c | 7 +-
> drivers/cxl/core/ras.c | 159 ++++++++++++++++++++++++++++++++--
> drivers/pci/pcie/aer_cxl_vh.c | 5 +-
> 4 files changed, 170 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
> index 9ceff8acf844..3197a71bf7b8 100644
> --- a/drivers/cxl/core/core.h
> +++ b/drivers/cxl/core/core.h
> @@ -156,6 +156,8 @@ pci_ers_result_t pci_error_detected(struct pci_dev *pdev,
> void pci_cor_error_detected(struct pci_dev *pdev);
> void cxl_cor_error_detected(struct device *dev);
> pci_ers_result_t cxl_error_detected(struct device *dev);
> +void cxl_port_cor_error_detected(struct device *dev);
> +pci_ers_result_t cxl_port_error_detected(struct device *dev);
> #else
> static inline int cxl_ras_init(void)
> {
> @@ -180,9 +182,17 @@ static inline pci_ers_result_t cxl_error_detected(struct device *dev)
> {
> return PCI_ERS_RESULT_NONE;
> }
> +static inline void cxl_port_cor_error_detected(struct device *dev) { }
> +static inline pci_ers_result_t cxl_port_error_detected(struct device *dev)
> +{
> + return PCI_ERS_RESULT_NONE;
Same question as endpoint error handler on if this should be a PCI_ERS_RESULT_PANIC instead.
> +}
> #endif // CONFIG_CXL_RAS
Wrong comment style.
>
> int cxl_gpf_port_setup(struct cxl_dport *dport);
> +struct cxl_port *find_cxl_port(struct device *dport_dev,
> + struct cxl_dport **dport);
> +struct cxl_port *find_cxl_port_by_uport(struct device *uport_dev);
>
> struct cxl_hdm;
> int cxl_hdm_decode_init(struct cxl_dev_state *cxlds, struct cxl_hdm *cxlhdm,
> diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
> index 56fa4ac33e8b..f34a44abb2c9 100644
> --- a/drivers/cxl/core/port.c
> +++ b/drivers/cxl/core/port.c
> @@ -1357,8 +1357,8 @@ static struct cxl_port *__find_cxl_port(struct cxl_find_port_ctx *ctx)
> return NULL;
> }
>
> -static struct cxl_port *find_cxl_port(struct device *dport_dev,
> - struct cxl_dport **dport)
> +struct cxl_port *find_cxl_port(struct device *dport_dev,
> + struct cxl_dport **dport)
> {
> struct cxl_find_port_ctx ctx = {
> .dport_dev = dport_dev,
> @@ -1561,7 +1561,7 @@ static int match_port_by_uport(struct device *dev, const void *data)
> * Function takes a device reference on the port device. Caller should do a
> * put_device() when done.
> */
> -static struct cxl_port *find_cxl_port_by_uport(struct device *uport_dev)
> +struct cxl_port *find_cxl_port_by_uport(struct device *uport_dev)
> {
> struct device *dev;
>
> @@ -1570,6 +1570,7 @@ static struct cxl_port *find_cxl_port_by_uport(struct device *uport_dev)
> return to_cxl_port(dev);
> return NULL;
> }
> +EXPORT_SYMBOL_NS_GPL(find_cxl_port_by_uport, "CXL");
>
> static int update_decoder_targets(struct device *dev, void *data)
> {
> diff --git a/drivers/cxl/core/ras.c b/drivers/cxl/core/ras.c
> index 9acfe24ba3bb..7e8d63c32d72 100644
> --- a/drivers/cxl/core/ras.c
> +++ b/drivers/cxl/core/ras.c
> @@ -250,6 +250,129 @@ static void cxl_dport_map_ras(struct cxl_dport *dport)
> dev_dbg(dev, "Failed to map RAS capability.\n");
> }
>
> +static void __iomem *cxl_get_ras_base(struct device *dev)
> +{
> + struct pci_dev *pdev = to_pci_dev(dev);
> +
> + switch (pci_pcie_type(pdev)) {
> + case PCI_EXP_TYPE_ROOT_PORT:
> + case PCI_EXP_TYPE_DOWNSTREAM:
> + {
> + struct cxl_dport *dport;
> + struct cxl_port *port __free(put_cxl_port) = find_cxl_port(&pdev->dev, &dport);
> +
> + if (!dport || !dport->dport_dev) {
> + pci_err(pdev, "Failed to find the CXL device");
> + return NULL;
> + }
> +
> + return dport->regs.ras;
> + }
> + case PCI_EXP_TYPE_UPSTREAM:
> + {
> + struct cxl_port *port __free(put_cxl_port) = find_cxl_port_by_uport(&pdev->dev);
> +
> + if (!port) {
> + pci_err(pdev, "Failed to find the CXL device");
> + return NULL;
> + }
> +
> + return port->uport_regs.ras;
> + }
> + }
> +
> + dev_warn_once(dev, "Error: Unsupported device type (%X)", pci_pcie_type(pdev));
> + return NULL;
> +}
> +
> +static struct device *pci_to_cxl_dev(struct pci_dev *pdev)
> +{
> + switch (pci_pcie_type(pdev)) {
> + case PCI_EXP_TYPE_ROOT_PORT:
> + case PCI_EXP_TYPE_DOWNSTREAM:
> + {
> + struct cxl_dport *dport;
> + struct cxl_port *port __free(put_cxl_port) = find_cxl_port(&pdev->dev, &dport);
> +
> + if (!port) {
> + pci_err(pdev, "Failed to find the CXL device");
> + return NULL;
> + }
> +
> + return dport->dport_dev;
> + }
> + case PCI_EXP_TYPE_UPSTREAM:
> + {
> + struct cxl_port *port __free(put_cxl_port) = find_cxl_port_by_uport(&pdev->dev);
> +
> + if (!port) {
> + pci_err(pdev, "Failed to find the CXL device");
> + return NULL;
> + }
> +
> + return port->uport_dev;
> + }
> + case PCI_EXP_TYPE_ENDPOINT:
> + {
> + struct cxl_dev_state *cxlds;
> +
> + if (!cxl_pci_drv_bound(pdev))
> + return NULL;
> +
> + cxlds = pci_get_drvdata(pdev);
> + return cxlds->dev;
> + }
> + }
> +
> + pci_warn_once(pdev, "Error: Unsupported device type (%X)", pci_pcie_type(pdev));
> + return NULL;
> +}
> +
> +/*
> + * Return 'struct device *' responsible for freeing pdev's CXL resources.
> + * Caller is responsible for reference count decrementing the return
> + * 'struct device *'.
> + *
> + * dev: Find the host of this dev
> + */
> +static struct device *get_cxl_host_dev(struct device *dev)
> +{
> + struct pci_dev *pdev = to_pci_dev(dev);
> +
> + switch (pci_pcie_type(pdev)) {
> + case PCI_EXP_TYPE_ROOT_PORT:
> + case PCI_EXP_TYPE_DOWNSTREAM:
> + {
> + struct cxl_dport *dport;
> + struct cxl_port *port __free(put_cxl_port) = find_cxl_port(&pdev->dev, &dport);
> +
> + if (!port) {
> + pci_err(pdev, "Failed to find the CXL device");
> + return NULL;
> + }
> +
> + return &port->dev;
I may just be tired, but won't the __free() action get called here unless you use no_free_ptr()?
You do the same thing with cxl_get_ras_base() and pci_to_cxl_dev() above, though I think it's the
intended behavior for the latter function.
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