[Intel-gfx] [PATCH 2/3] drm/i915/perf: Add support for report sizes that are not power of 2

[Umesh Nerlige Ramappa]

OA perf unit supports non-power of 2 report sizes. Enable support for
these sizes in the driver.

Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa at intel.com>
---
 drivers/gpu/drm/i915/i915_perf.c | 59 ++++++++++++--------------------
 1 file changed, 21 insertions(+), 38 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c
index 50b6d154fd46..482fca3da7de 100644
--- a/drivers/gpu/drm/i915/i915_perf.c
+++ b/drivers/gpu/drm/i915/i915_perf.c
@@ -450,7 +450,7 @@ static bool oa_buffer_check_unlocked(struct i915_perf_stream *stream)
 	u32 gtt_offset = i915_ggtt_offset(stream->oa_buffer.vma);
 	int report_size = stream->oa_buffer.format_size;
 	unsigned long flags;
-	u32 hw_tail;
+	u32 hw_tail, aging_tail;
 	u64 now;
 
 	/* We have to consider the (unlikely) possibility that read() errors
@@ -459,16 +459,17 @@ static bool oa_buffer_check_unlocked(struct i915_perf_stream *stream)
 	 */
 	spin_lock_irqsave(&stream->oa_buffer.ptr_lock, flags);
 
-	hw_tail = dev_priv->perf.ops.oa_hw_tail_read(stream);
+	hw_tail = dev_priv->perf.ops.oa_hw_tail_read(stream) - gtt_offset;
+	aging_tail = stream->oa_buffer.aging_tail - gtt_offset;
 
 	/* The tail pointer increases in 64 byte increments,
 	 * not in report_size steps...
 	 */
-	hw_tail &= ~(report_size - 1);
+	hw_tail = OA_TAKEN(hw_tail, (OA_TAKEN(hw_tail, aging_tail) % report_size));
 
 	now = ktime_get_mono_fast_ns();
 
-	if (hw_tail == stream->oa_buffer.aging_tail) {
+	if (hw_tail == aging_tail) {
 		/* If the HW tail hasn't move since the last check and the HW
 		 * tail has been aging for long enough, declare it the new
 		 * tail.
@@ -486,8 +487,6 @@ static bool oa_buffer_check_unlocked(struct i915_perf_stream *stream)
 		 * a read() in progress.
 		 */
 		head = stream->oa_buffer.head - gtt_offset;
-
-		hw_tail -= gtt_offset;
 		tail = hw_tail;
 
 		/* Walk the stream backward until we find at least 2 reports
@@ -613,7 +612,18 @@ static int append_oa_sample(struct i915_perf_stream *stream,
 	buf += sizeof(header);
 
 	if (sample_flags & SAMPLE_OA_REPORT) {
-		if (copy_to_user(buf, report, report_size))
+		u8 *oa_buf_end = stream->oa_buffer.vaddr + OA_BUFFER_SIZE;
+		int report_size_partial = oa_buf_end - report;
+
+		if (report_size_partial < report_size) {
+			if (copy_to_user(buf, report, report_size_partial))
+				return -EFAULT;
+			buf += report_size_partial;
+
+			if (copy_to_user(buf, stream->oa_buffer.vaddr,
+					report_size - report_size_partial))
+				return -EFAULT;
+		} else if (copy_to_user(buf, report, report_size))
 			return -EFAULT;
 	}
 
@@ -682,8 +692,8 @@ static int gen8_append_oa_reports(struct i915_perf_stream *stream,
 	 * only be incremented by multiples of the report size (notably also
 	 * all a power of two).
 	 */
-	if (WARN_ONCE(head > OA_BUFFER_SIZE || head % report_size ||
-		      tail > OA_BUFFER_SIZE || tail % report_size,
+	if (WARN_ONCE(head > OA_BUFFER_SIZE ||
+		      tail > OA_BUFFER_SIZE,
 		      "Inconsistent OA buffer pointers: head = %u, tail = %u\n",
 		      head, tail))
 		return -EIO;
@@ -697,20 +707,6 @@ static int gen8_append_oa_reports(struct i915_perf_stream *stream,
 		u32 ctx_id;
 		u32 reason;
 
-		/*
-		 * All the report sizes factor neatly into the buffer
-		 * size so we never expect to see a report split
-		 * between the beginning and end of the buffer.
-		 *
-		 * Given the initial alignment check a misalignment
-		 * here would imply a driver bug that would result
-		 * in an overrun.
-		 */
-		if (WARN_ON((OA_BUFFER_SIZE - head) < report_size)) {
-			DRM_ERROR("Spurious OA head ptr: non-integral report offset\n");
-			break;
-		}
-
 		/*
 		 * The reason field includes flags identifying what
 		 * triggered this specific report (mostly timer
@@ -956,8 +952,8 @@ static int gen7_append_oa_reports(struct i915_perf_stream *stream,
 	 * only be incremented by multiples of the report size (notably also
 	 * all a power of two).
 	 */
-	if (WARN_ONCE(head > OA_BUFFER_SIZE || head % report_size ||
-		      tail > OA_BUFFER_SIZE || tail % report_size,
+	if (WARN_ONCE(head > OA_BUFFER_SIZE ||
+		      tail > OA_BUFFER_SIZE,
 		      "Inconsistent OA buffer pointers: head = %u, tail = %u\n",
 		      head, tail))
 		return -EIO;
@@ -969,19 +965,6 @@ static int gen7_append_oa_reports(struct i915_perf_stream *stream,
 		u8 *report = oa_buf_base + head;
 		u32 *report32 = (void *)report;
 
-		/* All the report sizes factor neatly into the buffer
-		 * size so we never expect to see a report split
-		 * between the beginning and end of the buffer.
-		 *
-		 * Given the initial alignment check a misalignment
-		 * here would imply a driver bug that would result
-		 * in an overrun.
-		 */
-		if (WARN_ON((OA_BUFFER_SIZE - head) < report_size)) {
-			DRM_ERROR("Spurious OA head ptr: non-integral report offset\n");
-			break;
-		}
-
 		/* The report-ID field for periodic samples includes
 		 * some undocumented flags related to what triggered
 		 * the report and is never expected to be zero so we
-- 
2.20.1