According to bspec, some parts of HW expect the addresses to be in
a canonical form, where bits [63:48] == [47]. Let's convert addresses to
canonical form prior to relocating and return converted offsets to
userspace.

Cc: Chris Wilson <ch...@chris-wilson.co.uk>
Cc: Michel Thierry <michel.thie...@intel.com>
Signed-off-by: Michał Winiarski <michal.winiar...@intel.com>
---
 drivers/gpu/drm/i915/i915_gem_execbuffer.c | 9 ++++++---
 drivers/gpu/drm/i915/i915_gem_gtt.h        | 5 +++++
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c 
b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index a4c243c..9f27be9 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -395,7 +395,7 @@ i915_gem_execbuffer_relocate_entry(struct 
drm_i915_gem_object *obj,
        target_i915_obj = target_vma->obj;
        target_obj = &target_vma->obj->base;
 
-       target_offset = target_vma->node.start;
+       target_offset = gen8_canonical_addr(target_vma->node.start);
 
        /* Sandybridge PPGTT errata: We need a global gtt mapping for MI and
         * pipe_control writes because the gpu doesn't properly redirect them
@@ -583,6 +583,7 @@ i915_gem_execbuffer_reserve_vma(struct i915_vma *vma,
        struct drm_i915_gem_object *obj = vma->obj;
        struct drm_i915_gem_exec_object2 *entry = vma->exec_entry;
        uint64_t flags;
+       uint64_t offset;
        int ret;
 
        flags = PIN_USER;
@@ -623,8 +624,10 @@ i915_gem_execbuffer_reserve_vma(struct i915_vma *vma,
                        entry->flags |= __EXEC_OBJECT_HAS_FENCE;
        }
 
-       if (entry->offset != vma->node.start) {
-               entry->offset = vma->node.start;
+       offset = gen8_canonical_addr(vma->node.start);
+
+       if (entry->offset != offset) {
+               entry->offset = offset;
                *need_reloc = true;
        }
 
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.h 
b/drivers/gpu/drm/i915/i915_gem_gtt.h
index 877c32c..65e8f88 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.h
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.h
@@ -507,6 +507,11 @@ static inline size_t gen8_pte_count(uint64_t address, 
uint64_t length)
        return i915_pte_count(address, length, GEN8_PDE_SHIFT);
 }
 
+static inline uint64_t gen8_canonical_addr(uint64_t address)
+{
+       return ((int64_t)address << 16) >> 16;
+}
+
 static inline dma_addr_t
 i915_page_dir_dma_addr(const struct i915_hw_ppgtt *ppgtt, const unsigned n)
 {
-- 
2.5.0

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