drm/i915/perf: Allow non-privileged access when OA buffer is not sampled

SAMPLE_OA_REPORT enables sampling of OA reports from the OA buffer.
Since reports from OA buffer had system wide visibility, collecting
samples from the OA buffer was a privileged operation on previous
platforms. Prior to TGL, it was also necessary to sample the OA buffer
to normalize reports from MI REPORT PERF COUNT.

TGL has a dedicated OAR unit to sample perf reports for a specific
render context. This removes the necessity to sample OA buffer.

- If not sampling the OA buffer, allow non-privileged access. An earlier
  patch allows the non-privilege access:
  https://patchwork.freedesktop.org/patch/337716/?series=68582&rev=1
- Clear up the path for non-privileged access in this patch

Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
Fixes: 00a7f0d7155c ("drm/i915/tgl: Add perf support on TGL")
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191206194339.31356-1-umesh.nerlige.ramappa@intel.com
(cherry picked from commit 322d56aa3145a28445907ecc638a2c3aa3295c6b)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>

diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c
index 65d7c2e..0f6e1d7 100644 (file)
--- a/drivers/gpu/drm/i915/i915_perf.c
+++ b/drivers/gpu/drm/i915/i915_perf.c
@@ -2713,7 +2713,8 @@ static int i915_oa_stream_init(struct i915_perf_stream *stream,
                return -EINVAL;
        }
 
-       if (!(props->sample_flags & SAMPLE_OA_REPORT)) {
+       if (!(props->sample_flags & SAMPLE_OA_REPORT) &&
+           (INTEL_GEN(perf->i915) < 12 || !stream->ctx)) {
                DRM_DEBUG("Only OA report sampling supported\n");
                return -EINVAL;
        }
@@ -2745,7 +2746,7 @@ static int i915_oa_stream_init(struct i915_perf_stream *stream,
 
        format_size = perf->oa_formats[props->oa_format].size;
 
-       stream->sample_flags |= SAMPLE_OA_REPORT;
+       stream->sample_flags = props->sample_flags;
        stream->sample_size += format_size;
 
        stream->oa_buffer.format_size = format_size;