Re: [PATCH v6 11/11] drm/xe/configfs: Allow adding configurations for future VFs

[Rodrigo Vivi <rodrigo.vivi@intel.com>]

On Thu, Jul 31, 2025 at 09:33:39PM +0200, Michal Wajdeczko wrote:
> Since we are expecting that all configuration directory names
> will match some of the existing devices, we can't provide any
> configuration for the VFs until they are actually enabled.
> 
> But we can relax that restriction by just checking if there
> is a PF device that could create given VF. This is easy since
> all our PF devices are always present at function 0 and we can
> query PF device for number of VFs it could support.
> 
> Then for some system with PF device at 0000:00:02.0 we can add
> configs for all VFs:
> 
>   /sys/kernel/config/xe/
>   ├── 0000:00:02.0
>   │   └── ...
>   ├── 0000:00:02.1
>   │   └── ...
>   ├── 0000:00:02.2
>   │   └── ...
>   :
>   └── 0000:00:02.7
>       └── ...
> 
> Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
> Cc: Lucas De Marchi <lucas.demarchi@intel.com>
> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
> Cc: John Harrison <John.C.Harrison@Intel.com>
> Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com> #v3


Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

> ---
> v2: rebase and improve checks, fix include order
> v3: put correct device (Lucas)
> v4: rebase and change reporting
> ---
>  drivers/gpu/drm/xe/xe_configfs.c | 35 +++++++++++++++++++++++++++++---
>  1 file changed, 32 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_configfs.c b/drivers/gpu/drm/xe/xe_configfs.c
> index 0e2da7907afc..c2da2c60e321 100644
> --- a/drivers/gpu/drm/xe/xe_configfs.c
> +++ b/drivers/gpu/drm/xe/xe_configfs.c
> @@ -12,9 +12,9 @@
>  #include <linux/string.h>
>  
>  #include "xe_configfs.h"
> -#include "xe_module.h"
> -
>  #include "xe_hw_engine_types.h"
> +#include "xe_module.h"
> +#include "xe_pci_types.h"
>  
>  /**
>   * DOC: Xe Configfs
> @@ -285,6 +285,15 @@ static const struct xe_device_desc *xe_match_desc(struct pci_dev *pdev)
>  	return found ? (const void *)found->driver_data : NULL;
>  }
>  
> +static struct pci_dev *get_physfn_instead(struct pci_dev *virtfn)
> +{
> +	struct pci_dev *physfn = pci_physfn(virtfn);
> +
> +	pci_dev_get(physfn);
> +	pci_dev_put(virtfn);
> +	return physfn;
> +}
> +
>  static struct config_group *xe_config_make_device_group(struct config_group *group,
>  							const char *name)
>  {
> @@ -293,6 +302,7 @@ static struct config_group *xe_config_make_device_group(struct config_group *gro
>  	const struct xe_device_desc *match;
>  	struct pci_dev *pdev;
>  	char canonical[16];
> +	int vfnumber = 0;
>  	int ret;
>  
>  	ret = sscanf(name, "%x:%x:%x.%x", &domain, &bus, &slot, &function);
> @@ -306,12 +316,31 @@ static struct config_group *xe_config_make_device_group(struct config_group *gro
>  		return ERR_PTR(-EINVAL);
>  
>  	pdev = pci_get_domain_bus_and_slot(domain, bus, PCI_DEVFN(slot, function));
> +	if (!pdev && function)
> +		pdev = pci_get_domain_bus_and_slot(domain, bus, PCI_DEVFN(slot, 0));
> +	if (!pdev && slot)
> +		pdev = pci_get_domain_bus_and_slot(domain, bus, PCI_DEVFN(0, 0));
>  	if (!pdev)
>  		return ERR_PTR(-ENODEV);
>  
>  	match = xe_match_desc(pdev);
> -	if (!match)
> +
> +	if (PCI_DEVFN(slot, function) != pdev->devfn) {
> +		pdev = get_physfn_instead(pdev);
> +		vfnumber = PCI_DEVFN(slot, function) - pdev->devfn;
> +		if (!dev_is_pf(&pdev->dev) || vfnumber > pci_sriov_get_totalvfs(pdev)) {
> +			pci_dev_put(pdev);
> +			return ERR_PTR(-ENODEV);
> +		}
> +	}
> +
> +	match = xe_match_desc(pdev);
> +	if (match && vfnumber && !match->has_sriov) {
> +		pci_info(pdev, "xe driver does not support VFs on this device\n");
> +		match = NULL;
> +	} else if (!match) {
>  		pci_info(pdev, "xe driver does not support configuration of this device\n");
> +	}
>  
>  	pci_dev_put(pdev);
>  
> -- 
> 2.47.1
>