Re: [PATCH v2 04/10] drm/xe/pf: Allow to change VFs VRAM quota using sysfs

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

On Wed, Feb 18, 2026 at 09:55:46PM +0100, Michal Wajdeczko wrote:
> On current discrete platforms, PF will provision all VFs with a fair
> amount of the VRAM (LMEM) during VFs enabling. However, in some cases
> this automatic VRAM provisioning might be either non-reproducible or
> sub-optimal. This could break VF's migration or impact performance.
> 
> Expose per-VF VRAM quota read-write sysfs attributes to allow admin
> change default VRAM provisioning performed by the PF.
> 
>  /sys/bus/pci/drivers/xe/BDF/
>  ├── sriov_admin/
>      ├── .bulk_profile
>      │   └── vram_quota                 [RW] unsigned integer
>      ├── vf1/
>      │   └── profile
>      │       └── vram_quota             [RW] unsigned integer
>      ├── vf2/
>      │   └── profile
>      │       └── vram_quota             [RW] unsigned integer
> 
> Above values represent total provisioned VRAM from all tiles where
> VFs were assigned, and currently it's from all tiles always.
> 
> Note that changing VRAM provisioning is only possible when VF is
> not running, otherwise GuC will complain. To make sure that given
> VF is idle, triggering VF FLR might be needed.
> 
> Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
> Reviewed-by: Piotr Piórkowski <piotr.piorkowski@intel.com>
> ---
> v2: allow VRAM change only if LMTT (Piotr)

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

> ---
>  drivers/gpu/drm/xe/xe_sriov_pf_sysfs.c | 31 ++++++++++++++++++++++++--
>  1 file changed, 29 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_sriov_pf_sysfs.c b/drivers/gpu/drm/xe/xe_sriov_pf_sysfs.c
> index 82a1055985ba..aa05c143a4d6 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_device.h"
>  #include "xe_pci_sriov.h"
>  #include "xe_pm.h"
>  #include "xe_sriov.h"
> @@ -44,7 +45,8 @@ static int emit_choice(char *buf, int choice, const char * const *array, size_t
>   *     ├── .bulk_profile
>   *     │   ├── exec_quantum_ms
>   *     │   ├── preempt_timeout_us
> - *     │   └── sched_priority
> + *     │   ├── sched_priority
> + *     │   └── vram_quota
>   *     ├── pf/
>   *     │   ├── ...
>   *     │   ├── device -> ../../../BDF
> @@ -59,7 +61,8 @@ static int emit_choice(char *buf, int choice, const char * const *array, size_t
>   *     │   └── profile
>   *     │       ├── exec_quantum_ms
>   *     │       ├── preempt_timeout_us
> - *     │       └── sched_priority
> + *     │       ├── sched_priority
> + *     │       └── vram_quota
>   *     ├── vf2/
>   *     :
>   *     └── vfN/
> @@ -132,6 +135,7 @@ static XE_SRIOV_DEV_ATTR_WO(NAME)
>  
>  DEFINE_SIMPLE_BULK_PROVISIONING_SRIOV_DEV_ATTR_WO(exec_quantum_ms, eq, u32);
>  DEFINE_SIMPLE_BULK_PROVISIONING_SRIOV_DEV_ATTR_WO(preempt_timeout_us, pt, u32);
> +DEFINE_SIMPLE_BULK_PROVISIONING_SRIOV_DEV_ATTR_WO(vram_quota, vram, u64);
>  
>  static const char * const sched_priority_names[] = {
>  	[GUC_SCHED_PRIORITY_LOW] = "low",
> @@ -181,12 +185,26 @@ static struct attribute *bulk_profile_dev_attrs[] = {
>  	&xe_sriov_dev_attr_exec_quantum_ms.attr,
>  	&xe_sriov_dev_attr_preempt_timeout_us.attr,
>  	&xe_sriov_dev_attr_sched_priority.attr,
> +	&xe_sriov_dev_attr_vram_quota.attr,
>  	NULL
>  };
>  
> +static umode_t profile_dev_attr_is_visible(struct kobject *kobj,
> +					   struct attribute *attr, int index)
> +{
> +	struct xe_sriov_kobj *vkobj = to_xe_sriov_kobj(kobj);
> +
> +	if (attr == &xe_sriov_dev_attr_vram_quota.attr &&
> +	    !xe_device_has_lmtt(vkobj->xe))
> +		return 0;
> +
> +	return attr->mode;
> +}
> +
>  static const struct attribute_group bulk_profile_dev_attr_group = {
>  	.name = ".bulk_profile",
>  	.attrs = bulk_profile_dev_attrs,
> +	.is_visible = profile_dev_attr_is_visible,
>  };
>  
>  static const struct attribute_group *xe_sriov_dev_attr_groups[] = {
> @@ -228,6 +246,7 @@ static XE_SRIOV_VF_ATTR(NAME)
>  
>  DEFINE_SIMPLE_PROVISIONING_SRIOV_VF_ATTR(exec_quantum_ms, eq, u32, "%u\n");
>  DEFINE_SIMPLE_PROVISIONING_SRIOV_VF_ATTR(preempt_timeout_us, pt, u32, "%u\n");
> +DEFINE_SIMPLE_PROVISIONING_SRIOV_VF_ATTR(vram_quota, vram, u64, "%llu\n");
>  
>  static ssize_t xe_sriov_vf_attr_sched_priority_show(struct xe_device *xe, unsigned int vfid,
>  						    char *buf)
> @@ -274,6 +293,7 @@ static struct attribute *profile_vf_attrs[] = {
>  	&xe_sriov_vf_attr_exec_quantum_ms.attr,
>  	&xe_sriov_vf_attr_preempt_timeout_us.attr,
>  	&xe_sriov_vf_attr_sched_priority.attr,
> +	&xe_sriov_vf_attr_vram_quota.attr,
>  	NULL
>  };
>  
> @@ -286,6 +306,13 @@ static umode_t profile_vf_attr_is_visible(struct kobject *kobj,
>  	    !sched_priority_change_allowed(vkobj->vfid))
>  		return attr->mode & 0444;
>  
> +	if (attr == &xe_sriov_vf_attr_vram_quota.attr) {
> +		if (!IS_DGFX(vkobj->xe) || vkobj->vfid == PFID)
> +			return 0;
> +		if (!xe_device_has_lmtt(vkobj->xe))
> +			return attr->mode & 0444;
> +	}
> +
>  	return attr->mode;
>  }
>  
> -- 
> 2.47.1
>