diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index fc586fbd96b5c20c7da89483f50ef442d8c99c86..e4e57a51425e9ffaf0519f6671102e7a90d44edc 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -1573,7 +1573,8 @@ enum skl_disp_power_wells {
 #define RING_NOPID(base)	((base)+0x94)
 #define RING_IMR(base)		((base)+0xa8)
 #define RING_HWSTAM(base)	((base)+0x98)
-#define RING_TIMESTAMP(base)	((base)+0x358)
+#define RING_TIMESTAMP(base)		((base)+0x358)
+#define RING_TIMESTAMP_UDW(base)	((base)+0x358 + 4)
 #define   TAIL_ADDR		0x001FFFF8
 #define   HEAD_WRAP_COUNT	0xFFE00000
 #define   HEAD_WRAP_ONE		0x00200000
diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
index f0f97b288d0e3fdf4954febab36cd43999955620..03fdfbd3484cf2eaa78002a217cde082bccd9ee8 100644
--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -1261,12 +1261,14 @@ void intel_uncore_fini(struct drm_device *dev)
 #define GEN_RANGE(l, h) GENMASK(h, l)
 
 static const struct register_whitelist {
-	uint64_t offset;
+	uint32_t offset_ldw, offset_udw;
 	uint32_t size;
 	/* supported gens, 0x10 for 4, 0x30 for 4 and 5, etc. */
 	uint32_t gen_bitmask;
 } whitelist[] = {
-	{ RING_TIMESTAMP(RENDER_RING_BASE), 8, GEN_RANGE(4, 9) },
+	{ .offset_ldw = RING_TIMESTAMP(RENDER_RING_BASE),
+	  .offset_udw = RING_TIMESTAMP_UDW(RENDER_RING_BASE),
+	  .size = 8, .gen_bitmask = GEN_RANGE(4, 9) },
 };
 
 int i915_reg_read_ioctl(struct drm_device *dev,
@@ -1276,11 +1278,11 @@ int i915_reg_read_ioctl(struct drm_device *dev,
 	struct drm_i915_reg_read *reg = data;
 	struct register_whitelist const *entry = whitelist;
 	unsigned size;
-	u64 offset;
+	uint32_t offset_ldw, offset_udw;
 	int i, ret = 0;
 
 	for (i = 0; i < ARRAY_SIZE(whitelist); i++, entry++) {
-		if (entry->offset == (reg->offset & -entry->size) &&
+		if (entry->offset_ldw == (reg->offset & -entry->size) &&
 		    (1 << INTEL_INFO(dev)->gen & entry->gen_bitmask))
 			break;
 	}
@@ -1292,27 +1294,28 @@ int i915_reg_read_ioctl(struct drm_device *dev,
 	 * be naturally aligned (and those that are not so aligned merely
 	 * limit the available flags for that register).
 	 */
-	offset = entry->offset;
+	offset_ldw = entry->offset_ldw;
+	offset_udw = entry->offset_udw;
 	size = entry->size;
-	size |= reg->offset ^ offset;
+	size |= reg->offset ^ offset_ldw;
 
 	intel_runtime_pm_get(dev_priv);
 
 	switch (size) {
 	case 8 | 1:
-		reg->val = I915_READ64_2x32(offset, offset+4);
+		reg->val = I915_READ64_2x32(offset_ldw, offset_udw);
 		break;
 	case 8:
-		reg->val = I915_READ64(offset);
+		reg->val = I915_READ64(offset_ldw);
 		break;
 	case 4:
-		reg->val = I915_READ(offset);
+		reg->val = I915_READ(offset_ldw);
 		break;
 	case 2:
-		reg->val = I915_READ16(offset);
+		reg->val = I915_READ16(offset_ldw);
 		break;
 	case 1:
-		reg->val = I915_READ8(offset);
+		reg->val = I915_READ8(offset_ldw);
 		break;
 	default:
 		ret = -EINVAL;
diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
index 67cebe6d978fb77bf1906abf348c3d0abe938ea7..67ef73a5d6ebdffacb32b10dc453afbbabcb5b8d 100644
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -1079,6 +1079,12 @@ struct drm_i915_gem_context_destroy {
 };
 
 struct drm_i915_reg_read {
+	/*
+	 * Register offset.
+	 * For 64bit wide registers where the upper 32bits don't immediately
+	 * follow the lower 32bits, the offset of the lower 32bits must
+	 * be specified
+	 */
 	__u64 offset;
 	__u64 val; /* Return value */
 };