From: jsg <jsg@openbsd.org>
Date: Mon, 9 Oct 2023 02:35:47 +0000 (+0000)
Subject: drm/i915/gt: Fix reservation address in ggtt_reserve_guc_top
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=b10449e645b32931228a7712f768df8618bef27d;p=openbsd

drm/i915/gt: Fix reservation address in ggtt_reserve_guc_top

From Javier Pello
69dd84470b4deed45658f2717aef533ec4ceb43d in linux-6.1.y/6.1.56
b7599d241778d0b10cdf7a5c755aa7db9b83250c in mainline linux
---

diff --git a/sys/dev/pci/drm/i915/gt/intel_ggtt.c b/sys/dev/pci/drm/i915/gt/intel_ggtt.c
index ec9465e26fa..96fc3dd2398 100644
--- a/sys/dev/pci/drm/i915/gt/intel_ggtt.c
+++ b/sys/dev/pci/drm/i915/gt/intel_ggtt.c
@@ -529,20 +529,31 @@ void intel_ggtt_unbind_vma(struct i915_address_space *vm,
 	vm->clear_range(vm, vma_res->start, vma_res->vma_size);
 }
 
+/*
+ * Reserve the top of the GuC address space for firmware images. Addresses
+ * beyond GUC_GGTT_TOP in the GuC address space are inaccessible by GuC,
+ * which makes for a suitable range to hold GuC/HuC firmware images if the
+ * size of the GGTT is 4G. However, on a 32-bit platform the size of the GGTT
+ * is limited to 2G, which is less than GUC_GGTT_TOP, but we reserve a chunk
+ * of the same size anyway, which is far more than needed, to keep the logic
+ * in uc_fw_ggtt_offset() simple.
+ */
+#define GUC_TOP_RESERVE_SIZE (SZ_4G - GUC_GGTT_TOP)
+
 static int ggtt_reserve_guc_top(struct i915_ggtt *ggtt)
 {
-	u64 size;
+	u64 offset;
 	int ret;
 
 	if (!intel_uc_uses_guc(&ggtt->vm.gt->uc))
 		return 0;
 
-	GEM_BUG_ON(ggtt->vm.total <= GUC_GGTT_TOP);
-	size = ggtt->vm.total - GUC_GGTT_TOP;
+	GEM_BUG_ON(ggtt->vm.total <= GUC_TOP_RESERVE_SIZE);
+	offset = ggtt->vm.total - GUC_TOP_RESERVE_SIZE;
 
-	ret = i915_gem_gtt_reserve(&ggtt->vm, NULL, &ggtt->uc_fw, size,
-				   GUC_GGTT_TOP, I915_COLOR_UNEVICTABLE,
-				   PIN_NOEVICT);
+	ret = i915_gem_gtt_reserve(&ggtt->vm, NULL, &ggtt->uc_fw,
+				   GUC_TOP_RESERVE_SIZE, offset,
+				   I915_COLOR_UNEVICTABLE, PIN_NOEVICT);
 	if (ret)
 		drm_dbg(&ggtt->vm.i915->drm,
 			"Failed to reserve top of GGTT for GuC\n");