Re: [PATCH 12/14] drm/xe/pf: Add sysfs device symlinks to enabled VFs

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

On Mon, Oct 20, 2025 at 08:24:12PM +0200, Michal Wajdeczko wrote:
> For convenience, for every enabled VF add 'device' symlink from
> our SR-IOV admin VF folder to enabled sysfs PCI VF device entry.
> Remove all those links when disabling PCI VFs.
> 
> For completeness, add static 'device' symlink for the PF itself.
> 
>   /sys/bus/pci/drivers/xe/BDF/sriov_admin/
>   ├── pf
>   │   └── device -> ../../../BDF	# PF BDF
>   ├── vf1
>   │   └── device -> ../../../BDF'	# VF1 BDF
>   ├── vf2
>   │   └── device -> ../../../BDF"	# VF2 BDF
> 

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

> Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
> Cc: Lucas De Marchi <lucas.demarchi@intel.com>
> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
> ---
>  drivers/gpu/drm/xe/xe_pci_sriov.c      |  5 ++
>  drivers/gpu/drm/xe/xe_sriov_pf_sysfs.c | 93 ++++++++++++++++++++++++++
>  drivers/gpu/drm/xe/xe_sriov_pf_sysfs.h |  3 +
>  3 files changed, 101 insertions(+)
> 
> diff --git a/drivers/gpu/drm/xe/xe_pci_sriov.c b/drivers/gpu/drm/xe/xe_pci_sriov.c
> index 678e76703cd8..fb2fd1d9066d 100644
> --- a/drivers/gpu/drm/xe/xe_pci_sriov.c
> +++ b/drivers/gpu/drm/xe/xe_pci_sriov.c
> @@ -20,6 +20,7 @@
>  #include "xe_sriov_pf_control.h"
>  #include "xe_sriov_pf_helpers.h"
>  #include "xe_sriov_pf_provision.h"
> +#include "xe_sriov_pf_sysfs.h"
>  #include "xe_sriov_printk.h"
>  
>  static void pf_reset_vfs(struct xe_device *xe, unsigned int num_vfs)
> @@ -138,6 +139,8 @@ static int pf_enable_vfs(struct xe_device *xe, int num_vfs)
>  	xe_sriov_info(xe, "Enabled %u of %u VF%s\n",
>  		      num_vfs, total_vfs, str_plural(total_vfs));
>  
> +	xe_sriov_pf_sysfs_link_vfs(xe, num_vfs);
> +
>  	pf_engine_activity_stats(xe, num_vfs, true);
>  
>  	return num_vfs;
> @@ -165,6 +168,8 @@ static int pf_disable_vfs(struct xe_device *xe)
>  
>  	pf_engine_activity_stats(xe, num_vfs, false);
>  
> +	xe_sriov_pf_sysfs_unlink_vfs(xe, num_vfs);
> +
>  	pci_disable_sriov(pdev);
>  
>  	pf_reset_vfs(xe, num_vfs);
> diff --git a/drivers/gpu/drm/xe/xe_sriov_pf_sysfs.c b/drivers/gpu/drm/xe/xe_sriov_pf_sysfs.c
> index a6be3c88fa4f..c68acf6cd34f 100644
> --- a/drivers/gpu/drm/xe/xe_sriov_pf_sysfs.c
> +++ b/drivers/gpu/drm/xe/xe_sriov_pf_sysfs.c
> @@ -9,6 +9,7 @@
>  #include <drm/drm_managed.h>
>  
>  #include "xe_assert.h"
> +#include "xe_pci_sriov.h"
>  #include "xe_pm.h"
>  #include "xe_sriov.h"
>  #include "xe_sriov_pf.h"
> @@ -43,12 +44,14 @@ static int emit_choice(char *buf, int choice, const char * const *array, size_t
>   *     │   └── sched_priority
>   *     ├── pf/
>   *     │   ├── ...
> + *     │   ├── device -> ../../../BDF
>   *     │   └── profile
>   *     │       ├── exec_quantum_ms
>   *     │       ├── preempt_timeout_us
>   *     │       └── sched_priority
>   *     ├── vf1/
>   *     │   ├── ...
> + *     │   ├── device -> ../../../BDF.1
>   *     │   └── profile
>   *     │       ├── exec_quantum_ms
>   *     │       ├── preempt_timeout_us
> @@ -422,6 +425,11 @@ static int pf_sysfs_error(struct xe_device *xe, int err, const char *what)
>  	return err;
>  }
>  
> +static void pf_sysfs_note(struct xe_device *xe, int err, const char *what)
> +{
> +	xe_sriov_dbg(xe, "Failed to setup sysfs %s (%pe)\n", what, ERR_PTR(err));
> +}
> +
>  static void action_put_kobject(void *arg)
>  {
>  	struct kobject *kobj = arg;
> @@ -488,6 +496,29 @@ static int pf_setup_tree(struct xe_device *xe)
>  	return 0;
>  }
>  
> +static void action_rm_device_link(void *arg)
> +{
> +	struct kobject *kobj = arg;
> +
> +	sysfs_remove_link(kobj, "device");
> +}
> +
> +static int pf_link_pf_device(struct xe_device *xe)
> +{
> +	struct kobject *kobj = xe->sriov.pf.vfs[PFID].kobj;
> +	int err;
> +
> +	err = sysfs_create_link(kobj, &xe->drm.dev->kobj, "device");
> +	if (err)
> +		return pf_sysfs_error(xe, err, "PF device link");
> +
> +	err = devm_add_action_or_reset(xe->drm.dev, action_rm_device_link, kobj);
> +	if (err)
> +		return pf_sysfs_error(xe, err, "PF unlink action");
> +
> +	return 0;
> +}
> +
>  /**
>   * xe_sriov_pf_sysfs_init() - Setup PF's SR-IOV sysfs tree.
>   * @xe: the PF &xe_device to setup sysfs
> @@ -509,5 +540,67 @@ int xe_sriov_pf_sysfs_init(struct xe_device *xe)
>  	if (err)
>  		return err;
>  
> +	err = pf_link_pf_device(xe);
> +	if (err)
> +		return err;
> +
>  	return 0;
>  }
> +
> +/**
> + * xe_sriov_pf_sysfs_link_vfs() - Add VF's links in SR-IOV sysfs tree.
> + * @xe: the &xe_device where to update sysfs
> + * @num_vfs: number of enabled VFs to link
> + *
> + * This function is specific for the PF driver.
> + *
> + * This function will add symbolic links between VFs represented in the SR-IOV
> + * sysfs tree maintained by the PF and enabled VF PCI devices.
> + *
> + * The @xe_sriov_pf_sysfs_unlink_vfs() shall be used to remove those links.
> + */
> +void xe_sriov_pf_sysfs_link_vfs(struct xe_device *xe, unsigned int num_vfs)
> +{
> +	unsigned int totalvfs = xe_sriov_pf_get_totalvfs(xe);
> +	struct pci_dev *pf_pdev = to_pci_dev(xe->drm.dev);
> +	struct pci_dev *vf_pdev = NULL;
> +	unsigned int n;
> +	int err;
> +
> +	xe_assert(xe, IS_SRIOV_PF(xe));
> +	xe_assert(xe, num_vfs <= totalvfs);
> +
> +	for (n = 1; n <= num_vfs; n++) {
> +		vf_pdev = xe_pci_sriov_get_vf_pdev(pf_pdev, VFID(n));
> +		if (!vf_pdev)
> +			return pf_sysfs_note(xe, -ENOENT, "VF link");
> +
> +		err = sysfs_create_link(xe->sriov.pf.vfs[VFID(n)].kobj,
> +					&vf_pdev->dev.kobj, "device");
> +
> +		/* must balance xe_pci_sriov_get_vf_pdev() */
> +		pci_dev_put(vf_pdev);
> +
> +		if (err)
> +			return pf_sysfs_note(xe, err, "VF link");
> +	}
> +}
> +
> +/**
> + * xe_sriov_pf_sysfs_unlink_vfs() - Remove VF's links from SR-IOV sysfs tree.
> + * @xe: the &xe_device where to update sysfs
> + * @num_vfs: number of VFs to unlink
> + *
> + * This function shall be called only on the PF.
> + * This function will remove "device" links added by @xe_sriov_sysfs_link_vfs().
> + */
> +void xe_sriov_pf_sysfs_unlink_vfs(struct xe_device *xe, unsigned int num_vfs)
> +{
> +	unsigned int n;
> +
> +	xe_assert(xe, IS_SRIOV_PF(xe));
> +	xe_assert(xe, num_vfs <= xe_sriov_pf_get_totalvfs(xe));
> +
> +	for (n = 1; n <= num_vfs; n++)
> +		sysfs_remove_link(xe->sriov.pf.vfs[VFID(n)].kobj, "device");
> +}
> diff --git a/drivers/gpu/drm/xe/xe_sriov_pf_sysfs.h b/drivers/gpu/drm/xe/xe_sriov_pf_sysfs.h
> index 1e6698cc29d3..ae92ed1766e7 100644
> --- a/drivers/gpu/drm/xe/xe_sriov_pf_sysfs.h
> +++ b/drivers/gpu/drm/xe/xe_sriov_pf_sysfs.h
> @@ -10,4 +10,7 @@ struct xe_device;
>  
>  int xe_sriov_pf_sysfs_init(struct xe_device *xe);
>  
> +void xe_sriov_pf_sysfs_link_vfs(struct xe_device *xe, unsigned int num_vfs);
> +void xe_sriov_pf_sysfs_unlink_vfs(struct xe_device *xe, unsigned int num_vfs);
> +
>  #endif
> -- 
> 2.47.1
>