drm/i915/ttm: disallow CPU fallback mode for ccs pages

Falling back to memcpy/memset shouldn't be allowed if we know we have
CCS state to manage using the blitter. Otherwise we are potentially
leaving the aux CCS state in an unknown state, which smells like an info
leak.

Fixes: 48760ffe923a ("drm/i915/gt: Clear compress metadata for Flat-ccs objects")
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: Jon Bloomfield <jon.bloomfield@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Kenneth Graunke <kenneth@whitecape.org>
Cc: Akeem G Abodunrin <akeem.g.abodunrin@intel.com>
Cc: Ramalingam C <ramalingam.c@intel.com>
Reviewed-by: Ramalingam C <ramalingam.c@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220629174350.384910-12-matthew.auld@intel.com

1 files changed, 26 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.c b/drivers/gpu/drm/i915/gem/i915_gem_object.c
index 642a5d59ce26..ccec4055fde3 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_object.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_object.c
@@ -717,6 +717,32 @@ bool i915_gem_object_placement_possible(struct drm_i915_gem_object *obj,
 	return false;
 }
 
+/**
+ * i915_gem_object_needs_ccs_pages - Check whether the object requires extra
+ * pages when placed in system-memory, in order to save and later restore the
+ * flat-CCS aux state when the object is moved between local-memory and
+ * system-memory
+ * @obj: Pointer to the object
+ *
+ * Return: True if the object needs extra ccs pages. False otherwise.
+ */
+bool i915_gem_object_needs_ccs_pages(struct drm_i915_gem_object *obj)
+{
+	bool lmem_placement = false;
+	int i;
+
+	for (i = 0; i < obj->mm.n_placements; i++) {
+		/* Compression is not allowed for the objects with smem placement */
+		if (obj->mm.placements[i]->type == INTEL_MEMORY_SYSTEM)
+			return false;
+		if (!lmem_placement &&
+		    obj->mm.placements[i]->type == INTEL_MEMORY_LOCAL)
+			lmem_placement = true;
+	}
+
+	return lmem_placement;
+}
+
 void i915_gem_init__objects(struct drm_i915_private *i915)
 {
 	INIT_DELAYED_WORK(&i915->mm.free_work, __i915_gem_free_work);