[Intel-gfx] [PATCH] drm/i915: Always convert incoming exec offsets to non-canonical

[Michał Winiarski]

We're using non-canonical addresses in drm_mm, and we're making sure that
userspace is using canonical addressing - both in case of softpin
(verifying incoming offset) and when relocating (converting to canonical
when updating offset returned to userspace).
Unfortunately when considering the need for relocations, we're comparing
offset from userspace (in canonical form) with drm_mm node (in
non-canonical form), and as a result, we end up always relocating if our
offsets are in the "problematic" range.
Let's always convert the offsets to avoid the performance impact of
relocations.

Fixes: a5f0edf63bdf ("drm/i915: Avoid writing relocs with addresses in non-canonical form")
Cc: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Michel Thierry <michel.thierry at intel.com>
Reported-by: Michał Pyrzowski <michal.pyrzowski at intel.com>
Signed-off-by: Michał Winiarski <michal.winiarski at intel.com>
---
 drivers/gpu/drm/i915/i915_gem_execbuffer.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index 1298357..111b7f8 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -1184,14 +1184,14 @@ validate_exec_list(struct drm_device *dev,
 			if (exec[i].offset !=
 			    gen8_canonical_addr(exec[i].offset & PAGE_MASK))
 				return -EINVAL;
-
-			/* From drm_mm perspective address space is continuous,
-			 * so from this point we're always using non-canonical
-			 * form internally.
-			 */
-			exec[i].offset = gen8_noncanonical_addr(exec[i].offset);
 		}
 
+		/* From drm_mm perspective address space is continuous,
+		 * so from this point we're always using non-canonical
+		 * form internally.
+		 */
+		exec[i].offset = gen8_noncanonical_addr(exec[i].offset);
+
 		if (exec[i].alignment && !is_power_of_2(exec[i].alignment))
 			return -EINVAL;
 
-- 
2.9.3