drm/i915/perf: Parse 64bit report header formats correctly

Now that OA formats come in flavor of 64 bit reports, the report header
has 64 bit report-id, timestamp, context-id and gpu-ticks fields. When
filtering these reports, use the right width for these fields.

Note that upper dword of context id is reserved, so squash lower dword
only.

v2: (Ashutosh)
- Drop inline
- Update comment with dword definitions - report id and timestamp
Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
Reviewed-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230323225901.3743681-7-umesh.nerlige.ramappa@intel.com

drivers/gpu/drm/i915/i915_perf.c

@@ -441,6 +441,67 @@ static u32 gen7_oa_hw_tail_read(struct i915_perf_stream *stream)
 	return oastatus1 & GEN7_OASTATUS1_TAIL_MASK;
 }
 
+#define oa_report_header_64bit(__s) \
+	((__s)->oa_buffer.format->header == HDR_64_BIT)
+
+static u64 oa_report_id(struct i915_perf_stream *stream, void *report)
+{
+	return oa_report_header_64bit(stream) ? *(u64 *)report : *(u32 *)report;
+}
+
+static u64 oa_report_reason(struct i915_perf_stream *stream, void *report)
+{
+	return (oa_report_id(stream, report) >> OAREPORT_REASON_SHIFT) &
+	       (GRAPHICS_VER(stream->perf->i915) == 12 ?
+		OAREPORT_REASON_MASK_EXTENDED :
+		OAREPORT_REASON_MASK);
+}
+
+static void oa_report_id_clear(struct i915_perf_stream *stream, u32 *report)
+{
+	if (oa_report_header_64bit(stream))
+		*(u64 *)report = 0;
+	else
+		*report = 0;
+}
+
+static bool oa_report_ctx_invalid(struct i915_perf_stream *stream, void *report)
+{
+	return !(oa_report_id(stream, report) &
+	       stream->perf->gen8_valid_ctx_bit) &&
+	       GRAPHICS_VER(stream->perf->i915) <= 11;
+}
+
+static u64 oa_timestamp(struct i915_perf_stream *stream, void *report)
+{
+	return oa_report_header_64bit(stream) ?
+		*((u64 *)report + 1) :
+		*((u32 *)report + 1);
+}
+
+static void oa_timestamp_clear(struct i915_perf_stream *stream, u32 *report)
+{
+	if (oa_report_header_64bit(stream))
+		*(u64 *)&report[2] = 0;
+	else
+		report[1] = 0;
+}
+
+static u32 oa_context_id(struct i915_perf_stream *stream, u32 *report)
+{
+	u32 ctx_id = oa_report_header_64bit(stream) ? report[4] : report[2];
+
+	return ctx_id & stream->specific_ctx_id_mask;
+}
+
+static void oa_context_id_squash(struct i915_perf_stream *stream, u32 *report)
+{
+	if (oa_report_header_64bit(stream))
+		report[4] = INVALID_CTX_ID;
+	else
+		report[2] = INVALID_CTX_ID;
+}
+
 /**
  * oa_buffer_check_unlocked - check for data and update tail ptr state
  * @stream: i915 stream instance
@@ -509,21 +570,22 @@ static bool oa_buffer_check_unlocked(struct i915_perf_stream *stream)
 		hw_tail -= gtt_offset;
 		tail = hw_tail;
 
-		/* Walk the stream backward until we find a report with dword 0
-		 * & 1 not at 0. Since the circular buffer pointers progress by
-		 * increments of 64 bytes and that reports can be up to 256
-		 * bytes long, we can't tell whether a report has fully landed
-		 * in memory before the first 2 dwords of the following report
-		 * have effectively landed.
+		/* Walk the stream backward until we find a report with report
+		 * id and timestmap not at 0. Since the circular buffer pointers
+		 * progress by increments of 64 bytes and that reports can be up
+		 * to 256 bytes long, we can't tell whether a report has fully
+		 * landed in memory before the report id and timestamp of the
+		 * following report have effectively landed.
 		 *
 		 * This is assuming that the writes of the OA unit land in
 		 * memory in the order they were written to.
 		 * If not : (╯°□°）╯︵ ┻━┻
 		 */
 		while (OA_TAKEN(tail, aged_tail) >= report_size) {
-			u32 *report32 = (void *)(stream->oa_buffer.vaddr + tail);
+			void *report = stream->oa_buffer.vaddr + tail;
 
-			if (report32[0] != 0 || report32[1] != 0)
+			if (oa_report_id(stream, report) ||
+			    oa_timestamp(stream, report))
 				break;
 
 			tail = (tail - report_size) & (OA_BUFFER_SIZE - 1);
@@ -702,7 +764,7 @@ static int gen8_append_oa_reports(struct i915_perf_stream *stream,
 		u8 *report = oa_buf_base + head;
 		u32 *report32 = (void *)report;
 		u32 ctx_id;
-		u32 reason;
+		u64 reason;
 
 		/*
 		 * All the report sizes factor neatly into the buffer
@@ -725,16 +787,12 @@ static int gen8_append_oa_reports(struct i915_perf_stream *stream,
 		 * triggered this specific report (mostly timer
 		 * triggered or e.g. due to a context switch).
 		 *
-		 * This field is never expected to be zero so we can
-		 * check that the report isn't invalid before copying
-		 * it to userspace...
+		 * In MMIO triggered reports, some platforms do not set the
+		 * reason bit in this field and it is valid to have a reason
+		 * field of zero.
 		 */
-		reason = ((report32[0] >> OAREPORT_REASON_SHIFT) &
-			  (GRAPHICS_VER(stream->perf->i915) == 12 ?
-			   OAREPORT_REASON_MASK_EXTENDED :
-			   OAREPORT_REASON_MASK));
-
-		ctx_id = report32[2] & stream->specific_ctx_id_mask;
+		reason = oa_report_reason(stream, report);
+		ctx_id = oa_context_id(stream, report32);
 
 		/*
 		 * Squash whatever is in the CTX_ID field if it's marked as
@@ -744,9 +802,10 @@ static int gen8_append_oa_reports(struct i915_perf_stream *stream,
 		 * Note: that we don't clear the valid_ctx_bit so userspace can
 		 * understand that the ID has been squashed by the kernel.
 		 */
-		if (!(report32[0] & stream->perf->gen8_valid_ctx_bit) &&
-		    GRAPHICS_VER(stream->perf->i915) <= 11)
-			ctx_id = report32[2] = INVALID_CTX_ID;
+		if (oa_report_ctx_invalid(stream, report)) {
+			ctx_id = INVALID_CTX_ID;
+			oa_context_id_squash(stream, report32);
+		}
 
 		/*
 		 * NB: For Gen 8 the OA unit no longer supports clock gating
@@ -790,7 +849,7 @@ static int gen8_append_oa_reports(struct i915_perf_stream *stream,
 			 */
 			if (stream->ctx &&
 			    stream->specific_ctx_id != ctx_id) {
-				report32[2] = INVALID_CTX_ID;
+				oa_context_id_squash(stream, report32);
 			}
 
 			ret = append_oa_sample(stream, buf, count, offset,
@@ -802,11 +861,11 @@ static int gen8_append_oa_reports(struct i915_perf_stream *stream,
 		}
 
 		/*
-		 * Clear out the first 2 dword as a mean to detect unlanded
+		 * Clear out the report id and timestamp as a means to detect unlanded
 		 * reports.
 		 */
-		report32[0] = 0;
-		report32[1] = 0;
+		oa_report_id_clear(stream, report32);
+		oa_timestamp_clear(stream, report32);
 	}
 
 	if (start_offset != *offset) {

drivers/gpu/drm/i915/i915_perf_types.h

@@ -38,9 +38,15 @@ enum {
 	PERF_GROUP_INVALID = U32_MAX,
 };
 
+enum report_header {
+	HDR_32_BIT = 0,
+	HDR_64_BIT,
+};
+
 struct i915_oa_format {
 	u32 format;
 	int size;
+	enum report_header header;
 };
 
 struct i915_oa_reg {