[RFC PATCH 1/2] drm/i915: Add perf property support for context HW id

[Zhenyu Wang]

In order to support profiling for special context e.g vGPU context,
we can expose vGPU context hw id and enable i915 perf property to
get target context for profiling. This adds new perf property to
assign target context with hw id.

Jiao Pengyuan has helped to fix context reference bug in original code.

Cc: Jiao, Pengyuan <pengyuan.jiao at intel.com>
Cc: Niu, Bing <bing.niu at intel.com>
Cc: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
Cc: intel-gvt-dev at lists.freedesktop.org
Signed-off-by: Zhenyu Wang <zhenyuw at linux.intel.com>
---
 drivers/gpu/drm/i915/i915_perf.c | 37 +++++++++++++++++++++++++++++++++++++
 include/uapi/drm/i915_drm.h      |  5 +++++
 2 files changed, 42 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c
index d9f77a4d85db..350fd259b2d0 100644
--- a/drivers/gpu/drm/i915/i915_perf.c
+++ b/drivers/gpu/drm/i915/i915_perf.c
@@ -348,7 +348,9 @@ struct perf_open_properties {
 	u32 sample_flags;
 
 	u64 single_context:1;
+	u64 single_context_hw:1;
 	u64 ctx_handle;
+	u64 ctx_hw_id;
 
 	/* OA sampling state */
 	int metrics_set;
@@ -2555,6 +2557,28 @@ i915_perf_open_ioctl_locked(struct drm_i915_private *dev_priv,
 		}
 	}
 
+	if (props->single_context_hw) {
+		struct i915_gem_context *ctx;
+
+		mutex_lock(&dev_priv->drm.struct_mutex);
+		list_for_each_entry(ctx, &dev_priv->contexts.list, link) {
+			if (!i915_gem_context_is_default(ctx))
+				continue;
+
+			if (ctx->hw_id == props->ctx_hw_id) {
+				specific_ctx = ctx;
+				i915_gem_context_get(specific_ctx);
+				break;
+			}
+		}
+		mutex_unlock(&dev_priv->drm.struct_mutex);
+
+		if (!specific_ctx) {
+			DRM_DEBUG("Failed to look up HW context id.\n");
+			goto err;
+		}
+	}
+
 	/*
 	 * On Haswell the OA unit supports clock gating off for a specific
 	 * context and in this mode there's no visibility of metrics for the
@@ -2708,6 +2732,14 @@ static int read_properties_unlocked(struct drm_i915_private *dev_priv,
 			props->single_context = 1;
 			props->ctx_handle = value;
 			break;
+		case DRM_I915_PERF_PROP_CTX_HW_ID:
+			if (value >= MAX_CONTEXT_HW_ID) {
+				DRM_DEBUG("Invalid OA HW context ID\n");
+				return -EINVAL;
+			}
+			props->single_context_hw = 1;
+			props->ctx_hw_id = value;
+			break;
 		case DRM_I915_PERF_PROP_SAMPLE_OA:
 			props->sample_flags |= SAMPLE_OA_REPORT;
 			break;
@@ -2779,6 +2811,11 @@ static int read_properties_unlocked(struct drm_i915_private *dev_priv,
 		uprop += 2;
 	}
 
+	if (props->single_context && props->single_context_hw) {
+		DRM_DEBUG("Assign context handler and HW id simultaneously\n");
+		return -EINVAL;
+	}
+
 	return 0;
 }
 
diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
index 7ccbd6a2bbe0..ddafa556e290 100644
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -1381,6 +1381,11 @@ enum drm_i915_perf_property_id {
 	 */
 	DRM_I915_PERF_PROP_OA_EXPONENT,
 
+	/**
+	 * The value specifies ctx with hw_id
+	 */
+	DRM_I915_PERF_PROP_CTX_HW_ID,
+
 	DRM_I915_PERF_PROP_MAX /* non-ABI */
 };
 
-- 
2.13.2