Re: [RESEND v13 17/25] cxl: Introduce cxl_pci_drv_bound() to check for bound driver

["Bowman, Terry" <terry.bowman@amd.com>]

On 11/5/2025 4:26 PM, Gregory Price wrote:
> On Wed, Nov 05, 2025 at 02:03:31PM -0500, Gregory Price wrote:
>> On Wed, Nov 05, 2025 at 12:51:04PM -0500, Gregory Price wrote:
>>> [    2.697094] cxl_core 0000:0d:00.0: BAR 0 [mem 0xfe800000-0xfe80ffff 64bit]: not claimed; can't enable device
>>> [    2.697098] cxl_core 0000:0d:00.0: probe with driver cxl_core failed with error -22
>>>
>>> Probe order issue when CXL drivers are built-in maybe?
>>>
> moving it back but leaving the function seemed to work for me, i don't
> know what the implication of this is though (i.e. it's unclear to me
> why you moved it from point a to point b in the first place).
>
> (only tested this on QEMU)
Thanks for pointing this out.

I expect your changes will not work when using loadable modules (m instead of y). 

It appears cxl_pci_probe() is being called earlier due to the changes. The call stack is:
cxl_pci_probe()     
  pcim_enable_device(pdev);     <---- Silent exit here because cxl_pci_probe() fails below 
    pci_enable_device(struct pci_dev *dev)
      pci_enable_device_flags(struct pci_dev *dev, unsigned long flags)
        cxl_pci_probe()         <---- Returns failure due to resource reservation failure

Brief testing is showing the following works:
@@ -922,7 +924,8 @@ static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 
        rc = pcim_enable_device(pdev);
        if (rc)
-               return rc;
+               return -EPROBE_DEFER;
+


Terry

> ---
>
> diff --git a/drivers/cxl/Makefile b/drivers/cxl/Makefile
> index ff6add88b6ae..2caa90fa4bf2 100644
> --- a/drivers/cxl/Makefile
> +++ b/drivers/cxl/Makefile
> @@ -12,8 +12,10 @@ obj-$(CONFIG_CXL_PORT) += cxl_port.o
>  obj-$(CONFIG_CXL_ACPI) += cxl_acpi.o
>  obj-$(CONFIG_CXL_PMEM) += cxl_pmem.o
>  obj-$(CONFIG_CXL_MEM) += cxl_mem.o
> +obj-$(CONFIG_CXL_PCI) += cxl_pci.o
>
>  cxl_port-y := port.o
>  cxl_acpi-y := acpi.o
>  cxl_pmem-y := pmem.o security.o
>  cxl_mem-y := mem.o
> +cxl_pci-y := pci.o
> diff --git a/drivers/cxl/core/Makefile b/drivers/cxl/core/Makefile
> index 2937d0ddcce2..fa1d4aed28b9 100644
> --- a/drivers/cxl/core/Makefile
> +++ b/drivers/cxl/core/Makefile
> @@ -21,4 +21,3 @@ cxl_core-$(CONFIG_CXL_FEATURES) += features.o
>  cxl_core-$(CONFIG_CXL_EDAC_MEM_FEATURES) += edac.o
>  cxl_core-$(CONFIG_CXL_RAS) += ras.o
>  cxl_core-$(CONFIG_CXL_RCH_RAS) += ras_rch.o
> -cxl_core-$(CONFIG_CXL_PCI) += pci_drv.o
> diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
> index a7a0838c8f23..7c287b4fa699 100644
> --- a/drivers/cxl/core/core.h
> +++ b/drivers/cxl/core/core.h
> @@ -223,13 +223,4 @@ int cxl_set_feature(struct cxl_mailbox *cxl_mbox, const uuid_t *feat_uuid,
>  		    u16 *return_code);
>  #endif
>
> -#ifdef CONFIG_CXL_PCI
> -bool cxl_pci_drv_bound(struct pci_dev *pdev);
> -int cxl_pci_driver_init(void);
> -void cxl_pci_driver_exit(void);
> -#else
> -static inline bool cxl_pci_drv_bound(struct pci_dev *pdev) { return false; };
> -static inline int cxl_pci_driver_init(void) { return 0; }
> -static inline void cxl_pci_driver_exit(void) { }
> -#endif
>  #endif /* __CXL_CORE_H__ */
> diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
> index d19ebf052d76..ca02ad58fc57 100644
> --- a/drivers/cxl/core/port.c
> +++ b/drivers/cxl/core/port.c
> @@ -2520,8 +2520,6 @@ static __init int cxl_core_init(void)
>  	if (rc)
>  		goto err_ras;
>
> -	cxl_pci_driver_init();
> -
>  	return 0;
>
>  err_ras:
> @@ -2537,7 +2535,6 @@ static __init int cxl_core_init(void)
>
>  static void cxl_core_exit(void)
>  {
> -	cxl_pci_driver_exit();
>  	cxl_ras_exit();
>  	cxl_region_exit();
>  	bus_unregister(&cxl_bus_type);
> diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
> index 97e6c187e048..a2660d64c6eb 100644
> --- a/drivers/cxl/cxl.h
> +++ b/drivers/cxl/cxl.h
> @@ -941,4 +941,10 @@ u16 cxl_gpf_get_dvsec(struct device *dev);
>  #define devm_cxl_switch_port_decoders_setup DECLARE_TESTABLE(devm_cxl_switch_port_decoders_setup)
>  #endif
>
> +#ifdef CONFIG_CXL_PCI
> +bool cxl_pci_drv_bound(struct pci_dev *pdev);
> +#else
> +static inline bool cxl_pci_drv_bound(struct pci_dev *pdev) { return false; };
> +#endif
> +
>  #endif /* __CXL_H__ */
> diff --git a/drivers/cxl/core/pci_drv.c b/drivers/cxl/pci.c
> similarity index 99%
> rename from drivers/cxl/core/pci_drv.c
> rename to drivers/cxl/pci.c
> index bc3c959f7eb6..e6d741e15ac2 100644
> --- a/drivers/cxl/core/pci_drv.c
> +++ b/drivers/cxl/pci.c
> @@ -1189,7 +1189,7 @@ static void cxl_cper_work_fn(struct work_struct *work)
>  }
>  static DECLARE_WORK(cxl_cper_work, cxl_cper_work_fn);
>
> -int __init cxl_pci_driver_init(void)
> +static int __init cxl_pci_driver_init(void)
>  {
>  	int rc;
>
> @@ -1204,9 +1204,15 @@ int __init cxl_pci_driver_init(void)
>  	return rc;
>  }
>
> -void cxl_pci_driver_exit(void)
> +static void cxl_pci_driver_exit(void)
>  {
>  	cxl_cper_unregister_work(&cxl_cper_work);
>  	cancel_work_sync(&cxl_cper_work);
>  	pci_unregister_driver(&cxl_pci_driver);
>  }
> +
> +module_init(cxl_pci_driver_init);
> +module_exit(cxl_pci_driver_exit);
> +MODULE_DESCRIPTION("CXL: PCI manageability");
> +MODULE_LICENSE("GPL v2");
> +MODULE_IMPORT_NS("CXL");