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

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Message-Id: <20220502172908.3569799-1-robdclark@gmail.com>
Date:   Mon,  2 May 2022 10:29:08 -0700
From:   Rob Clark <robdclark@...il.com>
To:     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>,
        Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>,
        Abhinav Kumar <quic_abhinavk@...cinc.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH] drm/msm: Limit command submission when no IOMMU

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>
---
 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