[PATCH] drm/msm: Limit command submission when no IOMMU

[PATCH] drm/msm: Limit command submission when no IOMMU

[Rob Clark]

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>
---
 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:
 	 */
-- 
2.35.1

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

[Lucas Stach]

Am Montag, dem 02.05.2022 um 10:29 -0700 schrieb Rob Clark:
> 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.

I haven't followed MSM too closely, so ctx->aspace may also include the
GPU MMU, but if this really only includes the IOMMU (as the commit
message implies) then this breaks Freedreno on i.MX5.

Regards,
Lucas

> 
> Signed-off-by: Rob Clark <robdclark@chromium.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:
>  	 */

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

[Rob Clark]

On Tue, May 3, 2022 at 5:12 AM Lucas Stach <l.stach@pengutronix.de> wrote:
>
> Am Montag, dem 02.05.2022 um 10:29 -0700 schrieb Rob Clark:
> > 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.
>
> I haven't followed MSM too closely, so ctx->aspace may also include the
> GPU MMU, but if this really only includes the IOMMU (as the commit
> message implies) then this breaks Freedreno on i.MX5.

it includes the gpu mmu, so a2xx should be fine.

BR,
-R

> Regards,
> Lucas
>
> >
> > Signed-off-by: Rob Clark <robdclark@chromium.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:
> >        */
>
>

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

[Dmitry Baryshkov]

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