linux-kernel - Re: [PATCH v2 20/26] drm/xe/pf: Add helper to retrieve VF's LMEM object

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Message-ID: <db1669c3-a1d8-47cd-a321-b6cecffd8c6f@intel.com>
Date: Thu, 23 Oct 2025 22:25:08 +0200
From: Michal Wajdeczko <michal.wajdeczko@...el.com>
To: Michał Winiarski <michal.winiarski@...el.com>, "Alex
 Williamson" <alex.williamson@...hat.com>, Lucas De Marchi
	<lucas.demarchi@...el.com>, Thomas Hellström
	<thomas.hellstrom@...ux.intel.com>, Rodrigo Vivi <rodrigo.vivi@...el.com>,
	Jason Gunthorpe <jgg@...pe.ca>, Yishai Hadas <yishaih@...dia.com>, Kevin Tian
	<kevin.tian@...el.com>, <intel-xe@...ts.freedesktop.org>,
	<linux-kernel@...r.kernel.org>, <kvm@...r.kernel.org>, Matthew Brost
	<matthew.brost@...el.com>
CC: <dri-devel@...ts.freedesktop.org>, Jani Nikula
	<jani.nikula@...ux.intel.com>, Joonas Lahtinen
	<joonas.lahtinen@...ux.intel.com>, Tvrtko Ursulin <tursulin@...ulin.net>,
	David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, "Lukasz
 Laguna" <lukasz.laguna@...el.com>
Subject: Re: [PATCH v2 20/26] drm/xe/pf: Add helper to retrieve VF's LMEM
 object



On 10/22/2025 12:41 AM, Michał Winiarski wrote:
> From: Lukasz Laguna <lukasz.laguna@...el.com>
> 
> Instead of accessing VF's lmem_obj directly, introduce a helper function
> to make the access more convenient.
> 
> Signed-off-by: Lukasz Laguna <lukasz.laguna@...el.com>
> Signed-off-by: Michał Winiarski <michal.winiarski@...el.com>
> ---
>  drivers/gpu/drm/xe/xe_gt_sriov_pf_config.c | 31 ++++++++++++++++++++++
>  drivers/gpu/drm/xe/xe_gt_sriov_pf_config.h |  1 +
>  2 files changed, 32 insertions(+)
> 
> diff --git a/drivers/gpu/drm/xe/xe_gt_sriov_pf_config.c b/drivers/gpu/drm/xe/xe_gt_sriov_pf_config.c
> index c857879e28fe5..28d648c386487 100644
> --- a/drivers/gpu/drm/xe/xe_gt_sriov_pf_config.c
> +++ b/drivers/gpu/drm/xe/xe_gt_sriov_pf_config.c
> @@ -1643,6 +1643,37 @@ int xe_gt_sriov_pf_config_bulk_set_lmem(struct xe_gt *gt, unsigned int vfid,
>  					   "LMEM", n, err);
>  }
>  
> +static struct xe_bo *pf_get_vf_config_lmem_obj(struct xe_gt *gt, unsigned int vfid)
> +{
> +	struct xe_gt_sriov_config *config = pf_pick_vf_config(gt, vfid);
> +
> +	return config->lmem_obj;
> +}
> +
> +/**
> + * xe_gt_sriov_pf_config_get_lmem_obj - Take a reference to the struct &xe_bo backing VF LMEM.

    * xe_gt_sriov_pf_config_get_lmem_obj() - Take ...

> + * @gt: the &xe_gt
> + * @vfid: the VF identifier

since you assert vfid below, add "(can't be 0)"

> + *
> + * This function can only be called on PF.
> + * The caller is responsible for calling xe_bo_put() on the returned object.
> + *
> + * Return: pointer to struct &xe_bo backing VF LMEM (if any).
> + */
> +struct xe_bo *xe_gt_sriov_pf_config_get_lmem_obj(struct xe_gt *gt, unsigned int vfid)
> +{
> +	struct xe_bo *lmem_obj;
> +
> +	xe_gt_assert(gt, vfid);
> +
> +	mutex_lock(xe_gt_sriov_pf_master_mutex(gt));
> +	lmem_obj = pf_get_vf_config_lmem_obj(gt, vfid);
> +	xe_bo_get(lmem_obj);
> +	mutex_unlock(xe_gt_sriov_pf_master_mutex(gt));
> +
> +	return lmem_obj;

or just

{
	guard(mutex)(xe_gt_sriov_pf_master_mutex(gt));

	return xe_bo_get(pf_get_vf_config_lmem_obj(gt, vfid));
}

> +}
> +
>  static u64 pf_query_free_lmem(struct xe_gt *gt)
>  {
>  	struct xe_tile *tile = gt->tile;
> diff --git a/drivers/gpu/drm/xe/xe_gt_sriov_pf_config.h b/drivers/gpu/drm/xe/xe_gt_sriov_pf_config.h
> index 6916b8f58ebf2..03c5dc0cd5fef 100644
> --- a/drivers/gpu/drm/xe/xe_gt_sriov_pf_config.h
> +++ b/drivers/gpu/drm/xe/xe_gt_sriov_pf_config.h
> @@ -36,6 +36,7 @@ int xe_gt_sriov_pf_config_set_lmem(struct xe_gt *gt, unsigned int vfid, u64 size
>  int xe_gt_sriov_pf_config_set_fair_lmem(struct xe_gt *gt, unsigned int vfid, unsigned int num_vfs);
>  int xe_gt_sriov_pf_config_bulk_set_lmem(struct xe_gt *gt, unsigned int vfid, unsigned int num_vfs,
>  					u64 size);
> +struct xe_bo *xe_gt_sriov_pf_config_get_lmem_obj(struct xe_gt *gt, unsigned int vfid);
>  
>  u32 xe_gt_sriov_pf_config_get_exec_quantum(struct xe_gt *gt, unsigned int vfid);
>  int xe_gt_sriov_pf_config_set_exec_quantum(struct xe_gt *gt, unsigned int vfid, u32 exec_quantum);

probably we should block VF's reprovisioning during the SAVE/RESTORE,
but that could be done later as follow up

Reviewed-by: Michal Wajdeczko <michal.wajdeczko@...el.com>