drm/i915: Expose I915_EXEC_RESOURCE_STREAMER flag and getparam

Ensures that the batch buffer is executed by the resource streamer.
And will let userspace know whether Resource Streamer is supported in
the kernel.

v2: Don't skip 1<<15 for the exec flags (Jani Nikula)
v3: Use HAS_RESOURCE_STREAMER macro for execbuf validation (Chris Wilson)

(from getparam patch)

v2: Update I915_PARAM_HAS_RESOURCE_STREAMER so it's after
    I915_PARAM_HAS_GPU_RESET.
v3: Only advertise RS support for hardware that supports it.
v4: Add HAS_RESOURCE_STREAMER() macro (Chris)

Testcase: igt/gem_exec_params
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Kenneth Graunke <kenneth@whitecape.org>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Abdiel Janulgue <abdiel.janulgue@linux.intel.com>
[danvet: squash in getparam patch since it'd break bisect, suggested
by Chris.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index c5349fa..a42f165 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -167,6 +167,9 @@
 		value = i915.enable_hangcheck &&
 			intel_has_gpu_reset(dev);
 		break;
+	case I915_PARAM_HAS_RESOURCE_STREAMER:
+		value = HAS_RESOURCE_STREAMER(dev);
+		break;
 	default:
 		DRM_DEBUG("Unknown parameter %d\n", param->param);
 		return -EINVAL;
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 950a981..63daf4c 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2539,6 +2539,9 @@
 
 #define HAS_CSR(dev)	(IS_SKYLAKE(dev))
 
+#define HAS_RESOURCE_STREAMER(dev) (IS_HASWELL(dev) || \
+				    INTEL_INFO(dev)->gen >= 8)
+
 #define INTEL_PCH_DEVICE_ID_MASK		0xff00
 #define INTEL_PCH_IBX_DEVICE_ID_TYPE		0x3b00
 #define INTEL_PCH_CPT_DEVICE_ID_TYPE		0x1c00
diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index 600db74..83577c6 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -1490,6 +1490,20 @@
 		return -EINVAL;
 	}
 
+	if (args->flags & I915_EXEC_RESOURCE_STREAMER) {
+		if (!HAS_RESOURCE_STREAMER(dev)) {
+			DRM_DEBUG("RS is only allowed for Haswell, Gen8 and above\n");
+			return -EINVAL;
+		}
+		if (ring->id != RCS) {
+			DRM_DEBUG("RS is not available on %s\n",
+				 ring->name);
+			return -EINVAL;
+		}
+
+		dispatch_flags |= I915_DISPATCH_RS;
+	}
+
 	intel_runtime_pm_get(dev_priv);
 
 	ret = i915_mutex_lock_interruptible(dev);