2022-05-03 00:22:18

by Rob Clark

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

From: Rob Clark <[email protected]>

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 <[email protected]>
---
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


2022-05-03 14:19:49

by Lucas Stach

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

Am Montag, dem 02.05.2022 um 10:29 -0700 schrieb Rob Clark:
> From: Rob Clark <[email protected]>
>
> 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 <[email protected]>
> ---
> 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:
> */


2022-05-03 21:44:06

by Rob Clark

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

On Tue, May 3, 2022 at 5:12 AM Lucas Stach <[email protected]> wrote:
>
> Am Montag, dem 02.05.2022 um 10:29 -0700 schrieb Rob Clark:
> > From: Rob Clark <[email protected]>
> >
> > 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 <[email protected]>
> > ---
> > 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:
> > */
>
>

2022-05-05 20:40:21

by Dmitry Baryshkov

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

On 02/05/2022 20:29, Rob Clark wrote:
> From: Rob Clark <[email protected]>
>
> 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 <[email protected]>

Reviewed-by: Dmitry Baryshkov <[email protected]>

> ---
> 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