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Message-ID: <aa898db3-c52f-61d5-6a55-0d8b836343fb@linaro.org>
Date:   Wed, 4 May 2022 21:41:09 +0300
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Subject: Re: [PATCH] drm/msm: Limit command submission when no IOMMU
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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,
        Luca Weiss <luca@z3ntu.xyz>,
        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>,
        open list <linux-kernel@vger.kernel.org>
References: <20220502172908.3569799-1-robdclark@gmail.com>
From:   Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
In-Reply-To: <20220502172908.3569799-1-robdclark@gmail.com>
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Precedence: bulk

On 02/05/2022 20:29, Rob Clark wrote:
> From: Rob Clark <robdclark@chromium.org>
> 
> Running the GPU without an IOMMU is not really a supported (or sane)
> configuration.  Yet it can be useful during SoC bringup (ie. if the
> iommu driver doesn't work yet).
> 
> Lets limit it to users who already have /dev/mem access, to avoid the
> chance that a user accidentially configures kernel without IOMMU
> support.
> 
> Signed-off-by: Rob Clark <robdclark@chromium.org>

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

> ---
>   drivers/gpu/drm/msm/msm_gem_submit.c | 5 +++++
>   1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/gpu/drm/msm/msm_gem_submit.c b/drivers/gpu/drm/msm/msm_gem_submit.c
> index 23b68bc945f6..9cd8c8708990 100644
> --- a/drivers/gpu/drm/msm/msm_gem_submit.c
> +++ b/drivers/gpu/drm/msm/msm_gem_submit.c
> @@ -734,6 +734,11 @@ int msm_ioctl_gem_submit(struct drm_device *dev, void *data,
>   	if (args->pad)
>   		return -EINVAL;
>   
> +	if (unlikely(!ctx->aspace) && !capable(CAP_SYS_RAWIO)) {
> +		DRM_ERROR_RATELIMITED("IOMMU support or CAP_SYS_RAWIO required!\n");
> +		return -EPERM;
> +	}
> +
>   	/* for now, we just have 3d pipe.. eventually this would need to
>   	 * be more clever to dispatch to appropriate gpu module:
>   	 */


-- 
With best wishes
Dmitry