Re: [PATCH 13/14] drm/xe/pf: Allow to stop and reset VF using sysfs

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

On Mon, Oct 20, 2025 at 08:24:13PM +0200, Michal Wajdeczko wrote:
> It is expected that VFs activity will be monitored and in some
> cases admin might want to silence specific VF without killing
> the VM where it was attached.
> 
> Add write-only attributes to control GuC scheduling at VF level.
> 
>   /sys/bus/pci/drivers/xe/BDF/
>   ├── sriov_admin/
>       ├── vf1/
>       │   ├── reset		[WO] bool

This reset is the only thing in this series that I'm not 100% comfortable.
in the device symlink you already have the reset that does the right thing.

If I understood correctly this one here has the same behavior, but with
slightly different path... bypassing the pci subsystem.

I understand that your goal is to have it near the stop since you have to
stop and then reset. But It is still a bit strange.

If you get our only PF FLR supported case, we do need to unbind the driver
before echo 1 > /sys/../device/reset  and still the unbind is not a file
near the the reset.

So we can perhaps live without this double reset here.

Although not a big blocker from my side....

Lucas, Thomas, thoughts?

>       │   └── stop		[WO] bool
>       ├── vf2/
>       │   ├── reset		[WO] bool
>       │   └── stop		[WO] bool
> 
> Writing "1" or "y" (or whatever is recognized by the strtobool()
> function) to these files will trigger the change of the VF state
> to STOP (GuC will stop servicing the VF) or back to READY (GuC
> will start servicing this VF again but after completing the full
> sequence of the software initiated VF FLR).
> 
> 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_sriov_pf_sysfs.c | 52 ++++++++++++++++++++++++++
>  1 file changed, 52 insertions(+)
> 
> diff --git a/drivers/gpu/drm/xe/xe_sriov_pf_sysfs.c b/drivers/gpu/drm/xe/xe_sriov_pf_sysfs.c
> index c68acf6cd34f..f872013313c1 100644
> --- a/drivers/gpu/drm/xe/xe_sriov_pf_sysfs.c
> +++ b/drivers/gpu/drm/xe/xe_sriov_pf_sysfs.c
> @@ -13,6 +13,7 @@
>  #include "xe_pm.h"
>  #include "xe_sriov.h"
>  #include "xe_sriov_pf.h"
> +#include "xe_sriov_pf_control.h"
>  #include "xe_sriov_pf_helpers.h"
>  #include "xe_sriov_pf_provision.h"
>  #include "xe_sriov_pf_sysfs.h"
> @@ -52,6 +53,8 @@ static int emit_choice(char *buf, int choice, const char * const *array, size_t
>   *     ├── vf1/
>   *     │   ├── ...
>   *     │   ├── device -> ../../../BDF.1
> + *     │   ├── reset
> + *     │   ├── stop
>   *     │   └── profile
>   *     │       ├── exec_quantum_ms
>   *     │       ├── preempt_timeout_us
> @@ -291,8 +294,57 @@ static const struct attribute_group profile_vf_attr_group = {
>  	.is_visible = profile_vf_attr_is_visible,
>  };
>  
> +#define DEFINE_SIMPLE_CONTROL_SRIOV_VF_ATTR(NAME)					\
> +											\
> +static ssize_t xe_sriov_vf_attr_##NAME##_store(struct xe_device *xe, unsigned int vfid,	\
> +					       const char *buf, size_t count)		\
> +{											\
> +	bool yes;									\
> +	int err;									\
> +											\
> +	if (!vfid)									\
> +		return -EPERM;								\
> +											\
> +	err = kstrtobool(buf, &yes);							\
> +	if (err)									\
> +		return err;								\
> +	if (!yes)									\
> +		return count;								\
> +											\
> +	err = xe_sriov_pf_control_##NAME##_vf(xe, vfid);				\
> +	return err ?: count;								\
> +}											\
> +											\
> +static XE_SRIOV_VF_ATTR_WO(NAME)
> +
> +DEFINE_SIMPLE_CONTROL_SRIOV_VF_ATTR(stop);
> +DEFINE_SIMPLE_CONTROL_SRIOV_VF_ATTR(reset);
> +
> +static struct attribute *control_vf_attrs[] = {
> +	&xe_sriov_vf_attr_stop.attr,
> +	&xe_sriov_vf_attr_reset.attr,
> +	NULL
> +};
> +
> +static umode_t control_vf_attr_is_visible(struct kobject *kobj,
> +					  struct attribute *attr, int index)
> +{
> +	struct xe_sriov_kobj *vkobj = to_xe_sriov_kobj(kobj);
> +
> +	if (vkobj->vfid == PFID)
> +		return 0;
> +
> +	return attr->mode;
> +}
> +
> +static const struct attribute_group control_vf_attr_group = {
> +	.attrs = control_vf_attrs,
> +	.is_visible = control_vf_attr_is_visible,
> +};
> +
>  static const struct attribute_group *xe_sriov_vf_attr_groups[] = {
>  	&profile_vf_attr_group,
> +	&control_vf_attr_group,
>  	NULL
>  };
>  
> -- 
> 2.47.1
>