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Message-ID: <2fd35c28-0911-df87-c7e4-f7cbdba1f09d@collabora.com>
Date:   Thu, 7 Apr 2022 12:58:22 +0300
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Subject: Re: [PATCH v3 10/10] drm/msm: Add a way for userspace to allocate GPU
 iova
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To:     Rob Clark <robdclark@gmail.com>, dri-devel@lists.freedesktop.org
Cc:     freedreno@lists.freedesktop.org, linux-arm-msm@vger.kernel.org,
        Dmitry Baryshkov <dmitry.baryshkov@linaro.org>,
        Rob Clark <robdclark@chromium.org>,
        Sean Paul <sean@poorly.run>,
        Abhinav Kumar <quic_abhinavk@quicinc.com>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Akhil P Oommen <quic_akhilpo@quicinc.com>,
        Jonathan Marek <jonathan@marek.ca>,
        Jordan Crouse <jordan@cosmicpenguin.net>,
        Emma Anholt <emma@anholt.net>,
        Dan Carpenter <dan.carpenter@oracle.com>,
        open list <linux-kernel@vger.kernel.org>
References: <20220406214636.1156978-1-robdclark@gmail.com>
 <20220406214636.1156978-11-robdclark@gmail.com>
From:   Dmitry Osipenko <dmitry.osipenko@collabora.com>
In-Reply-To: <20220406214636.1156978-11-robdclark@gmail.com>
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On 4/7/22 00:46, Rob Clark wrote:
> From: Rob Clark <robdclark@chromium.org>
> 
> The motivation at this point is mainly native userspace mesa driver in a
> VM guest.  The one remaining synchronous "hotpath" is buffer allocation,
> because guest needs to wait to know the bo's iova before it can start
> emitting cmdstream/state that references the new bo.  By allocating the
> iova in the guest userspace, we no longer need to wait for a response
> from the host, but can just rely on the allocation request being
> processed before the cmdstream submission.  Allocation failures (OoM,
> etc) would just be treated as context-lost (ie. GL_GUILTY_CONTEXT_RESET)
> or subsequent allocations (or readpix, etc) can raise GL_OUT_OF_MEMORY.
> 
> v2: Fix inuse check
> v3: Change mismatched iova case to -EBUSY
> 
> Signed-off-by: Rob Clark <robdclark@chromium.org>
> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> ---
>  drivers/gpu/drm/msm/adreno/adreno_gpu.c | 10 ++++++
>  drivers/gpu/drm/msm/msm_drv.c           | 21 +++++++++++
>  drivers/gpu/drm/msm/msm_gem.c           | 48 +++++++++++++++++++++++++
>  drivers/gpu/drm/msm/msm_gem.h           |  8 +++++
>  drivers/gpu/drm/msm/msm_gem_vma.c       |  2 ++
>  include/uapi/drm/msm_drm.h              |  3 ++
>  6 files changed, 92 insertions(+)

Reviewed-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>