drm/i915: Always pin contexts into the high GGTT

Now that we have fast top-down insertion into the drm_mm, we can use it
for frequent runtime operations like insertion of the context object,
whereas before we limited it to the one-off insertion of the pinned
kernel context. Keeping the active context objects out of the mappable
region of the global GTT (except under memory pressure) improves our
ability to allocate mappable aperture region without triggering a GPU
stall.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170210101422.1598-1-chris@chris-wilson.co.ukReviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>

drivers/gpu/drm/i915/intel_lrc.c

@@ -773,11 +773,9 @@ static int execlists_context_pin(struct intel_engine_cs *engine,
 	}
 	GEM_BUG_ON(!ce->state);
 
-	flags = PIN_GLOBAL;
+	flags = PIN_GLOBAL | PIN_HIGH;
 	if (ctx->ggtt_offset_bias)
 		flags |= PIN_OFFSET_BIAS | ctx->ggtt_offset_bias;
-	if (i915_gem_context_is_kernel(ctx))
-		flags |= PIN_HIGH;
 
 	ret = i915_vma_pin(ce->state, 0, GEN8_LR_CONTEXT_ALIGN, flags);
 	if (ret)

drivers/gpu/drm/i915/intel_ringbuffer.c

@@ -2004,7 +2004,7 @@ intel_ring_free(struct intel_ring *ring)
 	kfree(ring);
 }
 
-static int context_pin(struct i915_gem_context *ctx, unsigned int flags)
+static int context_pin(struct i915_gem_context *ctx)
 {
 	struct i915_vma *vma = ctx->engine[RCS].state;
 	int ret;
@@ -2019,7 +2019,7 @@ static int context_pin(struct i915_gem_context *ctx, unsigned int flags)
 			return ret;
 	}
 
-	return i915_vma_pin(vma, 0, ctx->ggtt_alignment, PIN_GLOBAL | flags);
+	return i915_vma_pin(vma, 0, ctx->ggtt_alignment, PIN_GLOBAL | PIN_HIGH);
 }
 
 static int intel_ring_context_pin(struct intel_engine_cs *engine,
@@ -2034,13 +2034,7 @@ static int intel_ring_context_pin(struct intel_engine_cs *engine,
 		return 0;
 
 	if (ce->state) {
-		unsigned int flags;
-
-		flags = 0;
-		if (i915_gem_context_is_kernel(ctx))
-			flags = PIN_HIGH;
-
-		ret = context_pin(ctx, flags);
+		ret = context_pin(ctx);
 		if (ret)
 			goto error;
 	}