Commit 3c67ce06 authored by Umesh Nerlige Ramappa's avatar Umesh Nerlige Ramappa
Browse files

drm/i915/perf: Handle non-power-of-2 reports 



Some of the newer OA formats are not powers of 2. For those formats,
adjust the hw_tail accordingly when checking for new reports.

v2: (Ashutosh)
- Switch to OA_TAKEN for diff calculation
- Use OA_BUFFER_SIZE instead of the vma size
- Update comments

Signed-off-by: default avatarUmesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
Reviewed-by: default avatarAshutosh Dixit <ashutosh.dixit@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230323225901.3743681-8-umesh.nerlige.ramappa@intel.com
parent dbc9a5fb

drivers/gpu/drm/i915/i915_perf.c

+27 −24
Original line number Diff line number Diff line
@@ -534,6 +534,7 @@ static bool oa_buffer_check_unlocked(struct i915_perf_stream *stream) 
	bool pollin;

	u32 hw_tail;

	u64 now;

	u32 partial_report_size;



	/* We have to consider the (unlikely) possibility that read() errors

	 * could result in an OA buffer reset which might reset the head and
@@ -543,10 +544,15 @@ static bool oa_buffer_check_unlocked(struct i915_perf_stream *stream) 


	hw_tail = stream->perf->ops.oa_hw_tail_read(stream);



	/* The tail pointer increases in 64 byte increments,

	 * not in report_size steps...

	/* The tail pointer increases in 64 byte increments, not in report_size

	 * steps. Also the report size may not be a power of 2. Compute

	 * potentially partially landed report in the OA buffer

	 */

	hw_tail &= ~(report_size - 1);

	partial_report_size = OA_TAKEN(hw_tail, stream->oa_buffer.tail);

	partial_report_size %= report_size;



	/* Subtract partial amount off the tail */

	hw_tail = gtt_offset + OA_TAKEN(hw_tail, partial_report_size);



	now = ktime_get_mono_fast_ns();
@@ -669,6 +675,8 @@ static int append_oa_sample(struct i915_perf_stream *stream, 
{

	int report_size = stream->oa_buffer.format->size;

	struct drm_i915_perf_record_header header;

	int report_size_partial;

	u8 *oa_buf_end;



	header.type = DRM_I915_PERF_RECORD_SAMPLE;

	header.pad = 0;
@@ -682,8 +690,20 @@ static int append_oa_sample(struct i915_perf_stream *stream, 
		return -EFAULT;

	buf += sizeof(header);



	if (copy_to_user(buf, report, report_size))

	oa_buf_end = stream->oa_buffer.vaddr + OA_BUFFER_SIZE;

	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;

	}



	(*offset) += header.size;
@@ -747,12 +767,11 @@ static int gen8_append_oa_reports(struct i915_perf_stream *stream, 
	 * An out of bounds or misaligned head or tail pointer implies a driver

	 * bug since we validate + align the tail pointers we read from the

	 * hardware and we are in full control of the head pointer which should

	 * only be incremented by multiples of the report size (notably also

	 * all a power of two).

	 * only be incremented by multiples of the report size.

	 */

	if (drm_WARN_ONCE(&uncore->i915->drm,

			  head > OA_BUFFER_SIZE || head % report_size ||

			  tail > OA_BUFFER_SIZE || tail % report_size,

			  head > OA_BUFFER_SIZE ||

			  tail > OA_BUFFER_SIZE,

			  "Inconsistent OA buffer pointers: head = %u, tail = %u\n",

			  head, tail))

		return -EIO;
@@ -766,22 +785,6 @@ static int gen8_append_oa_reports(struct i915_perf_stream *stream, 
		u32 ctx_id;

		u64 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 (drm_WARN_ON(&uncore->i915->drm,

				(OA_BUFFER_SIZE - head) < report_size)) {

			drm_err(&uncore->i915->drm,

				"Spurious OA head ptr: non-integral report offset\n");

			break;

		}



		/*

		 * The reason field includes flags identifying what

		 * triggered this specific report (mostly timer