[RFC 03/10] drm/i915/gvt: context submission pvmmio optimization

[Xiaolin Zhang <xiaolin.zhang@intel.com>]

It is performance optimization to reduce mmio trap numbers from 4 to
1 durning ELSP porting writing (context submission).

When context subission, to cache elsp_data[4] values in
the shared page, the last elsp_data[0] port writing will be trapped
to gvt for real context submission.

Use PVMMIO_ELSP_SUBMIT to control this level of pvmmio optimization.

Signed-off-by: Xiaolin Zhang <xiaolin.zhang@intel.com>
---
 drivers/gpu/drm/i915/i915_params.h |  2 +-
 drivers/gpu/drm/i915/intel_lrc.c   | 37 ++++++++++++++++++++++++++++++++++++-
 2 files changed, 37 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_params.h b/drivers/gpu/drm/i915/i915_params.h
index 0f6a38b..6c81c87 100644
--- a/drivers/gpu/drm/i915/i915_params.h
+++ b/drivers/gpu/drm/i915/i915_params.h
@@ -69,7 +69,7 @@
 	param(bool, enable_dp_mst, true) \
 	param(bool, enable_dpcd_backlight, false) \
 	param(bool, enable_gvt, false) \
-	param(int, enable_pvmmio, 0)
+	param(int, enable_pvmmio, PVMMIO_ELSP_SUBMIT)
 
 #define MEMBER(T, member, ...) T member;
 struct i915_params {
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 4b28225..cdc713c 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -451,7 +451,12 @@ static void execlists_submit_ports(struct intel_engine_cs *engine)
 {
 	struct intel_engine_execlists *execlists = &engine->execlists;
 	struct execlist_port *port = execlists->port;
+	u32 __iomem *elsp =
+		engine->i915->regs + i915_mmio_reg_offset(RING_ELSP(engine));
+	u32 *elsp_data;
 	unsigned int n;
+	u32 descs[4];
+	int i = 0;
 
 	/*
 	 * We can skip acquiring intel_runtime_pm_get() here as it was taken
@@ -494,8 +499,24 @@ static void execlists_submit_ports(struct intel_engine_cs *engine)
 			GEM_BUG_ON(!n);
 			desc = 0;
 		}
+		if (PVMMIO_LEVEL_ENABLE(engine->i915, PVMMIO_ELSP_SUBMIT)) {
+			GEM_BUG_ON(i >= 4);
+			descs[i] = upper_32_bits(desc);
+			descs[i + 1] = lower_32_bits(desc);
+			i += 2;
+		} else {
+			write_desc(execlists, desc, n);
+		}
+	}
 
-		write_desc(execlists, desc, n);
+	if (PVMMIO_LEVEL_ENABLE(engine->i915, PVMMIO_ELSP_SUBMIT)) {
+		spin_lock(&engine->i915->shared_page_lock);
+		elsp_data = engine->i915->shared_page->elsp_data;
+		*elsp_data = descs[0];
+		*(elsp_data + 1) = descs[1];
+		*(elsp_data + 2) = descs[2];
+		writel(descs[3], elsp);
+		spin_unlock(&engine->i915->shared_page_lock);
 	}
 
 	/* we need to manually load the submit queue */
@@ -538,11 +559,25 @@ static void inject_preempt_context(struct intel_engine_cs *engine)
 	struct intel_engine_execlists *execlists = &engine->execlists;
 	struct intel_context *ce =
 		to_intel_context(engine->i915->preempt_context, engine);
+	u32 __iomem *elsp =
+		engine->i915->regs + i915_mmio_reg_offset(RING_ELSP(engine));
+	u32 *elsp_data;
 	unsigned int n;
 
 	GEM_BUG_ON(execlists->preempt_complete_status !=
 		   upper_32_bits(ce->lrc_desc));
 
+	if (PVMMIO_LEVEL_ENABLE(engine->i915, PVMMIO_ELSP_SUBMIT)) {
+		spin_lock(&engine->i915->shared_page_lock);
+		elsp_data = engine->i915->shared_page->elsp_data;
+		*elsp_data = 0;
+		*(elsp_data + 1) = 0;
+		*(elsp_data + 2) = upper_32_bits(ce->lrc_desc);
+		writel(lower_32_bits(ce->lrc_desc), elsp);
+		spin_unlock(&engine->i915->shared_page_lock);
+		return;
+	}
+
 	/*
 	 * Switch to our empty preempt context so
 	 * the state of the GPU is known (idle).
-- 
1.8.3.1

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