linux-kernel - Re: [PATCH v4 5/7] drm/gpuvm: Add a flags field to drm_gpuvm_map_req/drm_gpuva_op

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Message-ID: <rquyd5sq4y6dhnnbqcmnorvhzvui6kbpysol6idinuwajlmawn@awv2uqosdacl>
Date: Tue, 22 Jul 2025 20:21:25 +0100
From: Adrian Larumbe <adrian.larumbe@...labora.com>
To: Caterina Shablia <caterina.shablia@...labora.com>
Cc: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
	Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
	David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
	Frank Binns <frank.binns@...tec.com>, Matt Coster <matt.coster@...tec.com>, 
	Karol Herbst <kherbst@...hat.com>, Lyude Paul <lyude@...hat.com>, 
	Danilo Krummrich <dakr@...nel.org>, Boris Brezillon <boris.brezillon@...labora.com>, 
	Steven Price <steven.price@....com>, Liviu Dudau <liviu.dudau@....com>, 
	Lucas De Marchi <lucas.demarchi@...el.com>, 
	Thomas Hellström <thomas.hellstrom@...ux.intel.com>, Rodrigo Vivi <rodrigo.vivi@...el.com>, 
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org, nouveau@...ts.freedesktop.org, 
	intel-xe@...ts.freedesktop.org, asahi@...ts.linux.dev, Asahi Lina <lina@...hilina.net>
Subject: Re: [PATCH v4 5/7] drm/gpuvm: Add a flags field to
 drm_gpuvm_map_req/drm_gpuva_op_map

On 07.07.2025 17:04, Caterina Shablia wrote:
> From: Asahi Lina <lina@...hilina.net>
>
> drm_gpuva objects have a flags field. Currently, this can be managed by
> drivers out-of-band, without any special handling in drm_gpuvm.
>
> To be able to introduce flags that do affect the logic in the drm_gpuvm
> core, we need to plumb it through the map calls. This will allow the
> core to check the flags on map and alter the merge/split logic depending
> on the requested flags and the flags of the existing drm_gpuva ranges
> that are being split.
>
> Signed-off-by: Asahi Lina <lina@...hilina.net>
> Signed-off-by: Caterina Shablia <caterina.shablia@...labora.com>
> ---
>  drivers/gpu/drm/drm_gpuvm.c | 7 +++++++
>  include/drm/drm_gpuvm.h     | 9 +++++++++
>  2 files changed, 16 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_gpuvm.c b/drivers/gpu/drm/drm_gpuvm.c
> index dc3c2f906400..dd949a8853b0 100644
> --- a/drivers/gpu/drm/drm_gpuvm.c
> +++ b/drivers/gpu/drm/drm_gpuvm.c
> @@ -2063,6 +2063,7 @@ op_map_cb(const struct drm_gpuvm_ops *fn, void *priv,
>  	op.map.va.range = req->va.range;
>  	op.map.gem.obj = req->gem.obj;
>  	op.map.gem.offset = req->gem.offset;
> +	op.map.flags = req->flags;
>
>  	return fn->sm_step_map(&op, priv);
>  }
> @@ -2175,6 +2176,7 @@ __drm_gpuvm_sm_map(struct drm_gpuvm *gpuvm,
>  					.va.range = range - req->va.range,
>  					.gem.obj = obj,
>  					.gem.offset = offset + req->va.range,
> +					.flags = va->flags,
>  				};
>  				struct drm_gpuva_op_unmap u = {
>  					.va = va,
> @@ -2193,6 +2195,7 @@ __drm_gpuvm_sm_map(struct drm_gpuvm *gpuvm,
>  				.va.range = ls_range,
>  				.gem.obj = obj,
>  				.gem.offset = offset,
> +				.flags = va->flags,
>  			};
>  			struct drm_gpuva_op_unmap u = { .va = va };
>
> @@ -2219,6 +2222,7 @@ __drm_gpuvm_sm_map(struct drm_gpuvm *gpuvm,
>  					.gem.obj = obj,
>  					.gem.offset = offset + ls_range +
>  						      req->va.range,
> +					.flags = va->flags,
>  				};
>
>  				ret = op_remap_cb(ops, priv, &p, &n, &u);
> @@ -2247,6 +2251,7 @@ __drm_gpuvm_sm_map(struct drm_gpuvm *gpuvm,
>  					.va.range = end - req_end,
>  					.gem.obj = obj,
>  					.gem.offset = offset + req_end - addr,
> +					.flags = va->flags,
>  				};
>  				struct drm_gpuva_op_unmap u = {
>  					.va = va,
> @@ -2290,6 +2295,7 @@ __drm_gpuvm_sm_unmap(struct drm_gpuvm *gpuvm,
>  			prev.va.range = req_addr - addr;
>  			prev.gem.obj = obj;
>  			prev.gem.offset = offset;
> +			prev.flags = va->flags;
>
>  			prev_split = true;
>  		}
> @@ -2299,6 +2305,7 @@ __drm_gpuvm_sm_unmap(struct drm_gpuvm *gpuvm,
>  			next.va.range = end - req_end;
>  			next.gem.obj = obj;
>  			next.gem.offset = offset + (req_end - addr);
> +			next.flags = va->flags;
>
>  			next_split = true;
>  		}
> diff --git a/include/drm/drm_gpuvm.h b/include/drm/drm_gpuvm.h
> index a6e6c33fc10b..f77a89e791f1 100644
> --- a/include/drm/drm_gpuvm.h
> +++ b/include/drm/drm_gpuvm.h
> @@ -847,6 +847,11 @@ struct drm_gpuva_op_map {
>  		 */
>  		struct drm_gem_object *obj;
>  	} gem;
> +
> +	/**
> +	 * @flags: requested flags for the &drm_gpuva for this mapping
> +	 */
> +	enum drm_gpuva_flags flags;
>  };
>
>  /**
> @@ -1074,6 +1079,9 @@ struct drm_gpuvm_map_req {
>  		/** @offset: offset in the GEM */
>  		u64 offset;
>  	} gem;
> +
> +	/** @flags: combination of DRM_GPUVA_ flags describing the mapping properties. */
> +	enum drm_gpuva_flags flags;

Wouldn't this be better expressed as a u32 combination of enum drm_gpuva_flags flags?
Calling it 'flags' makes me feel like any OR'd combination of enum values would be possible.

>  };
>
>  struct drm_gpuva_ops *
> @@ -1097,6 +1105,7 @@ void drm_gpuva_ops_free(struct drm_gpuvm *gpuvm,
>  static inline void drm_gpuva_init_from_op(struct drm_gpuva *va,
>  					  struct drm_gpuva_op_map *op)
>  {
> +	va->flags = op->flags;
>  	va->va.addr = op->va.addr;
>  	va->va.range = op->va.range;
>  	va->gem.obj = op->gem.obj;
> --
> 2.47.2

Adrian Larumbe