drm/i915/uc: Reserve upper range of GGTT

GuC and HuC depend on struct_mutex for device reinitialization. Moving
away from this dependency requires perma-pinning the firmware images in
GGTT.  The upper portion of the GuC address space has a sizeable hole
(several MB) that is inaccessible by GuC. Reserve this range within GGTT
as it can comfortably hold GuC/HuC firmware images.

v2: Reserve node rather than insert (Chris)
    Simpler determination of node start/size (Daniele)
    Move reserve/release out to intel_guc.* files

v3: Reserve starting at GUC_GGTT_TOP only and bail if this
    fails (Chris)
Signed-off-by: Fernando Pacheco <fernando.pacheco@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20190419230015.18121-3-fernando.pacheco@intel.com

drivers/gpu/drm/i915/i915_gem_gtt.c

@@ -2752,6 +2752,12 @@ int i915_gem_init_ggtt(struct drm_i915_private *dev_priv)
 	if (ret)
 		return ret;
 
+	if (USES_GUC(dev_priv)) {
+		ret = intel_guc_reserve_ggtt_top(&dev_priv->guc);
+		if (ret)
+			goto err_reserve;
+	}
+
 	/* Clear any non-preallocated blocks */
 	drm_mm_for_each_hole(entry, &ggtt->vm.mm, hole_start, hole_end) {
 		DRM_DEBUG_KMS("clearing unused GTT space: [%lx, %lx]\n",
@@ -2766,12 +2772,14 @@ int i915_gem_init_ggtt(struct drm_i915_private *dev_priv)
 	if (INTEL_PPGTT(dev_priv) == INTEL_PPGTT_ALIASING) {
 		ret = i915_gem_init_aliasing_ppgtt(dev_priv);
 		if (ret)
-			goto err;
+			goto err_appgtt;
 	}
 
 	return 0;
 
-err:
+err_appgtt:
+	intel_guc_release_ggtt_top(&dev_priv->guc);
+err_reserve:
 	drm_mm_remove_node(&ggtt->error_capture);
 	return ret;
 }
@@ -2797,6 +2805,8 @@ void i915_ggtt_cleanup_hw(struct drm_i915_private *dev_priv)
 	if (drm_mm_node_allocated(&ggtt->error_capture))
 		drm_mm_remove_node(&ggtt->error_capture);
 
+	intel_guc_release_ggtt_top(&dev_priv->guc);
+
 	if (drm_mm_initialized(&ggtt->vm.mm)) {
 		intel_vgt_deballoon(dev_priv);
 		i915_address_space_fini(&ggtt->vm);
@@ -3371,17 +3381,6 @@ int i915_ggtt_probe_hw(struct drm_i915_private *dev_priv)
 	if (ret)
 		return ret;
 
-	/* Trim the GGTT to fit the GuC mappable upper range (when enabled).
-	 * This is easier than doing range restriction on the fly, as we
-	 * currently don't have any bits spare to pass in this upper
-	 * restriction!
-	 */
-	if (USES_GUC(dev_priv)) {
-		ggtt->vm.total = min_t(u64, ggtt->vm.total, GUC_GGTT_TOP);
-		ggtt->mappable_end =
-			min_t(u64, ggtt->mappable_end, ggtt->vm.total);
-	}
-
 	if ((ggtt->vm.total - 1) >> 32) {
 		DRM_ERROR("We never expected a Global GTT with more than 32bits"
 			  " of address space! Found %lldM!\n",

drivers/gpu/drm/i915/i915_gem_gtt.h

@@ -384,6 +384,7 @@ struct i915_ggtt {
 	u32 pin_bias;
 
 	struct drm_mm_node error_capture;
+	struct drm_mm_node uc_fw;
 };
 
 struct i915_hw_ppgtt {

drivers/gpu/drm/i915/intel_guc.c

@@ -721,3 +721,30 @@ u32 intel_guc_reserved_gtt_size(struct intel_guc *guc)
 {
 	return guc_to_i915(guc)->wopcm.guc.size;
 }
+
+int intel_guc_reserve_ggtt_top(struct intel_guc *guc)
+{
+	struct drm_i915_private *i915 = guc_to_i915(guc);
+	struct i915_ggtt *ggtt = &i915->ggtt;
+	u64 size;
+	int ret;
+
+	size = ggtt->vm.total - GUC_GGTT_TOP;
+
+	ret = i915_gem_gtt_reserve(&ggtt->vm, &ggtt->uc_fw, size,
+				   GUC_GGTT_TOP, I915_COLOR_UNEVICTABLE,
+				   PIN_NOEVICT);
+	if (ret)
+		DRM_DEBUG_DRIVER("GuC: failed to reserve top of ggtt\n");
+
+	return ret;
+}
+
+void intel_guc_release_ggtt_top(struct intel_guc *guc)
+{
+	struct drm_i915_private *i915 = guc_to_i915(guc);
+	struct i915_ggtt *ggtt = &i915->ggtt;
+
+	if (drm_mm_node_allocated(&ggtt->uc_fw))
+		drm_mm_remove_node(&ggtt->uc_fw);
+}

drivers/gpu/drm/i915/intel_guc.h

@@ -173,6 +173,8 @@ int intel_guc_suspend(struct intel_guc *guc);
 int intel_guc_resume(struct intel_guc *guc);
 struct i915_vma *intel_guc_allocate_vma(struct intel_guc *guc, u32 size);
 u32 intel_guc_reserved_gtt_size(struct intel_guc *guc);
+int intel_guc_reserve_ggtt_top(struct intel_guc *guc);
+void intel_guc_release_ggtt_top(struct intel_guc *guc);
 
 static inline int intel_guc_sanitize(struct intel_guc *guc)
 {