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Message-ID: <c6ce663d-dd69-46a2-7b55-359169b6c03c@linux.intel.com>
Date:   Tue, 10 Oct 2023 08:40:17 +0200
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Subject: Re: [PATCH drm-misc-next v6 4/6] drm/gpuvm: track/lock/validate
 external/evicted objects
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To:     Danilo Krummrich <dakr@redhat.com>, airlied@gmail.com,
        daniel@ffwll.ch, matthew.brost@intel.com, sarah.walker@imgtec.com,
        donald.robson@imgtec.com, boris.brezillon@collabora.com,
        christian.koenig@amd.com, faith@gfxstrand.net
Cc:     dri-devel@lists.freedesktop.org, nouveau@lists.freedesktop.org,
        linux-kernel@vger.kernel.org
References: <20231008233212.13815-1-dakr@redhat.com>
 <20231008233212.13815-5-dakr@redhat.com>
From:   =?UTF-8?Q?Thomas_Hellstr=c3=b6m?= 
        <thomas.hellstrom@linux.intel.com>
In-Reply-To: <20231008233212.13815-5-dakr@redhat.com>
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On 10/9/23 01:32, Danilo Krummrich wrote:
> Currently the DRM GPUVM offers common infrastructure to track GPU VA
> allocations and mappings, generically connect GPU VA mappings to their
> backing buffers and perform more complex mapping operations on the GPU VA
> space.
>
> However, there are more design patterns commonly used by drivers, which
> can potentially be generalized in order to make the DRM GPUVM represent
> a basis for GPU-VM implementations. In this context, this patch aims
> at generalizing the following elements.
>
> 1) Provide a common dma-resv for GEM objects not being used outside of
>     this GPU-VM.
>
> 2) Provide tracking of external GEM objects (GEM objects which are
>     shared with other GPU-VMs).
>
> 3) Provide functions to efficiently lock all GEM objects dma-resv the
>     GPU-VM contains mappings of.
>
> 4) Provide tracking of evicted GEM objects the GPU-VM contains mappings
>     of, such that validation of evicted GEM objects is accelerated.
>
> 5) Provide some convinience functions for common patterns.
>
> Big thanks to Boris Brezillon for his help to figure out locking for
> drivers updating the GPU VA space within the fence signalling path.
>
> Suggested-by: Matthew Brost <matthew.brost@intel.com>
> Signed-off-by: Danilo Krummrich <dakr@redhat.com>
>
> +/**
> + * drm_gpuvm_resv_add_fence - add fence to private and all extobj
> + * dma-resv
> + * @gpuvm: the &drm_gpuvm to add a fence to
> + * @exec: the &drm_exec locking context
> + * @fence: fence to add
> + * @private_usage: private dma-resv usage
> + * @extobj_usage: extobj dma-resv usage
> + */
> +void
> +drm_gpuvm_resv_add_fence(struct drm_gpuvm *gpuvm,
> +			 struct drm_exec *exec,
> +			 struct dma_fence *fence,
> +			 enum dma_resv_usage private_usage,
> +			 enum dma_resv_usage extobj_usage)
> +{
> +	struct drm_gem_object *obj;
> +	unsigned long index;
> +
> +	drm_exec_for_each_locked_object(exec, index, obj) {
> +		dma_resv_assert_held(obj->resv);
> +		dma_resv_add_fence(obj->resv, fence,
> +				   drm_gpuvm_is_extobj(gpuvm, obj) ?
> +				   private_usage : extobj_usage);

It looks like private_usage and extobj_usage are mixed up above?


> +	}
> +}
> +EXPORT_SYMBOL_GPL(drm_gpuvm_resv_add_fence);
> +

Thanks,

Thomas