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From: Chris Wilson <chris@chris-wilson.co.uk>
To: intel-gfx@lists.freedesktop.org
Subject: [PATCH 11/13] drm/i915: Prevent mmap access through the GTT of snooped pages
Date: Thu, 14 Apr 2011 10:03:45 +0100	[thread overview]
Message-ID: <1302771827-26112-12-git-send-email-chris@chris-wilson.co.uk> (raw)
In-Reply-To: <1302771827-26112-1-git-send-email-chris@chris-wilson.co.uk>

The docs have a dire warning not to attempt to access snooped (the old
style of cache sharing on pre-SandyBridge chipsets) pages through the GTT.
Prevent userspace from doing so by sending them a SIGBUS if they try.

[Now it is possible with a bit of extra complexity to map the snooped
CPU page into the vma and return that through i915_gem_fault() instead.
The question is: is it simpler to do that workaround in the kernel than
it is to do it in userspace?]

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
---
 drivers/gpu/drm/i915/i915_gem.c |   10 ++++++++++
 1 files changed, 10 insertions(+), 0 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index dd2dc9d..1f57f99 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1211,6 +1211,16 @@ int i915_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 
 	trace_i915_gem_object_fault(obj, page_offset, true, write);
 
+	/* The docs warn of dire consequences if we try to write to a snooped
+	 * page through the GTT. So kill the driver/app early with a SIGBUS.
+	 */
+	if (INTEL_INFO(dev)->gen < 6 && obj->cache_level != I915_CACHE_NONE) {
+		DRM_DEBUG("Attempting to read a snooped page through the GTT, "
+			  "this is illegal on pre-SandyBridge chipsets.\n");
+		ret = -EINVAL;
+		goto unlock;
+	}
+
 	/* Now bind it into the GTT if needed */
 	if (!obj->map_and_fenceable) {
 		ret = i915_gem_object_unbind(obj);
-- 
1.7.4.1

  parent reply	other threads:[~2011-04-14  9:03 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-04-14  9:03 i915 llc for -next Chris Wilson
2011-04-14  9:03 ` [PATCH 01/13] drm/i915: Rename agp_type to cache_level Chris Wilson
2011-04-14 12:39   ` Keith Packard
2011-04-14 20:57     ` [PATCH] " Chris Wilson
2011-04-14  9:03 ` [PATCH 02/13] drm/i915: Do not clflush snooped objects Chris Wilson
2011-04-14  9:03 ` [PATCH 03/13] drm/i915: Introduce i915_gem_object_finish_gpu() Chris Wilson
2011-04-14 16:01   ` Daniel Vetter
2011-04-14  9:03 ` [PATCH 04/13] drm/i915: Introduce i915_gem_object_finish_gtt() Chris Wilson
2011-04-14 16:12   ` Daniel Vetter
2011-04-14 20:20     ` Chris Wilson
2011-05-04 16:47   ` Keith Packard
2011-04-14  9:03 ` [PATCH 05/13] drm/i915/gtt: Split out i915_gem_gtt_rebind_object() Chris Wilson
2011-04-14 16:52   ` Daniel Vetter
2011-04-14  9:03 ` [PATCH 06/13] drm/i915: Add an interface to dynamically change the cache level Chris Wilson
2011-04-14 16:54   ` Daniel Vetter
2011-04-14  9:03 ` [PATCH 07/13] drm/i915: Mark the cursor and the overlay as being part of the display planes Chris Wilson
2011-05-04 17:09   ` Keith Packard
2011-05-04 18:28     ` Chris Wilson
2011-05-04 18:46       ` Keith Packard
2011-05-04 19:47         ` Chris Wilson
2011-04-14  9:03 ` [PATCH 08/13] drm/i915: Pin after setting to the display plane Chris Wilson
2011-04-14 17:34   ` Daniel Vetter
2011-04-14 21:31     ` Chris Wilson
2011-04-15  6:04   ` [PATCH 1/2] drm/i915: Combine pinning " Chris Wilson
2011-04-15  6:04     ` [PATCH 2/2] drm/i915: Use the uncached domain for the display planes Chris Wilson
2011-04-16 10:54       ` Daniel Vetter
2011-04-15 12:11     ` [PATCH 1/2] drm/i915: Combine pinning after setting to the display plane Daniel Vetter
2011-04-16  6:26       ` Chris Wilson
2011-04-16  6:27       ` [PATCH] drm/i915: Combine pinning with " Chris Wilson
2011-04-16 10:52         ` Daniel Vetter
2011-04-16 11:00           ` Chris Wilson
2011-04-14  9:03 ` [PATCH 09/13] drm/i915: Use the uncached domain for the display planes Chris Wilson
2011-04-14  9:03 ` [PATCH 10/13] drm/i915: Use the CPU domain for snooped pwrites Chris Wilson
2011-04-14 17:40   ` Daniel Vetter
2011-04-14  9:03 ` Chris Wilson [this message]
2011-05-04 17:30   ` [PATCH 11/13] drm/i915: Prevent mmap access through the GTT of snooped pages Keith Packard
2011-04-14  9:03 ` [PATCH 12/13] drm/i915: Prevent mixing of snooped and tiling modes for old chipsets Chris Wilson
2011-04-14 17:43   ` Daniel Vetter
2011-04-14 20:26     ` Chris Wilson
2011-05-04 17:32   ` Keith Packard
2011-04-14  9:03 ` [PATCH 13/13] drm/i915: Use the LLC mode on gen6 for everything but display Chris Wilson
2011-04-15  6:12 ` i915 llc for -next Chris Wilson

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