linux-kernel - Re: [PATCH] drm/msm: Limit command submission when no IOMMU

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Date:   Wed, 4 May 2022 21:41:09 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Rob Clark <robdclark@...il.com>, dri-devel@...ts.freedesktop.org
Cc:     freedreno@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org,
        Luca Weiss <luca@...tu.xyz>,
        Rob Clark <robdclark@...omium.org>,
        Sean Paul <sean@...rly.run>,
        Abhinav Kumar <quic_abhinavk@...cinc.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drm/msm: Limit command submission when no IOMMU

On 02/05/2022 20:29, Rob Clark wrote:
> From: Rob Clark <robdclark@...omium.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@...omium.org>

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.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