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drm/i915/gt: Always try to reserve GGTT address 0x0

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Since writing to address 0 is a very common mistake, let's try to avoid
putting anything sensitive there.

References: https://gitlab.freedesktop.org/drm/intel/-/issues/2989
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210125125033.23656-1-chris@chris-wilson.co.uk
Cc: stable@vger.kernel.org
(cherry picked from commit 56b429cc584c6ed8b895d8d8540959655db1ff73)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
This commit is contained in:
Chris Wilson 2021-01-25 12:50:33 +00:00 committed by Jani Nikula
parent f6e98a1809
commit 489140b5ba
1 changed files with 35 additions and 12 deletions
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47
drivers/gpu/drm/i915/gt/intel_ggtt.c
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@ -526,16 +526,39 @@ static int init_ggtt(struct i915_ggtt *ggtt)
mutex_init(&ggtt->error_mutex);
if (ggtt->mappable_end) {
/* Reserve a mappable slot for our lockless error capture */
ret = drm_mm_insert_node_in_range(&ggtt->vm.mm,
&ggtt->error_capture,
PAGE_SIZE, 0,
I915_COLOR_UNEVICTABLE,
0, ggtt->mappable_end,
DRM_MM_INSERT_LOW);
if (ret)
return ret;
/*
* Reserve a mappable slot for our lockless error capture.
*
* We strongly prefer taking address 0x0 in order to protect
* other critical buffers against accidental overwrites,
* as writing to address 0 is a very common mistake.
*
* Since 0 may already be in use by the system (e.g. the BIOS
* framebuffer), we let the reservation fail quietly and hope
* 0 remains reserved always.
*
* If we fail to reserve 0, and then fail to find any space
* for an error-capture, remain silent. We can afford not
* to reserve an error_capture node as we have fallback
* paths, and we trust that 0 will remain reserved. However,
* the only likely reason for failure to insert is a driver
* bug, which we expect to cause other failures...
*/
ggtt->error_capture.size = I915_GTT_PAGE_SIZE;
ggtt->error_capture.color = I915_COLOR_UNEVICTABLE;
if (drm_mm_reserve_node(&ggtt->vm.mm, &ggtt->error_capture))
drm_mm_insert_node_in_range(&ggtt->vm.mm,
&ggtt->error_capture,
ggtt->error_capture.size, 0,
ggtt->error_capture.color,
0, ggtt->mappable_end,
DRM_MM_INSERT_LOW);
}
if (drm_mm_node_allocated(&ggtt->error_capture))
drm_dbg(&ggtt->vm.i915->drm,
"Reserved GGTT:[%llx, %llx] for use by error capture\n",
ggtt->error_capture.start,
ggtt->error_capture.start + ggtt->error_capture.size);
/*
* The upper portion of the GuC address space has a sizeable hole
@ -548,9 +571,9 @@ static int init_ggtt(struct i915_ggtt *ggtt)
/* Clear any non-preallocated blocks */
drm_mm_for_each_hole(entry, &ggtt->vm.mm, hole_start, hole_end) {
drm_dbg_kms(&ggtt->vm.i915->drm,
"clearing unused GTT space: [%lx, %lx]\n",
hole_start, hole_end);
drm_dbg(&ggtt->vm.i915->drm,
"clearing unused GTT space: [%lx, %lx]\n",
hole_start, hole_end);
ggtt->vm.clear_range(&ggtt->vm, hole_start,
hole_end - hole_start);
}