[Intel-gfx] [PATCH v2 7/8] drm/i915: Create vgpu specific write MMIO to reduce traps

[Yu Zhang]

In the virtualized environment, forcewake operations are not
necessory for the driver, because mmio accesses will be trapped
and emulated by the host side, and real forcewake operations are
also done in the host. New mmio write handlers are added to directly
call the __raw_i915_write, therefore will reduce many traps and
increase the overall performance for drivers runing in the VM
with Intel GVT-g enhancement.

v2: 
take Chris' comments:
        - register the mmio hooks in intel_uncore_init()

Signed-off-by: Yu Zhang <yu.c.zhang at linux.intel.com>
Signed-off-by: Jike Song <jike.song at intel.com>
Signed-off-by: Kevin Tian <kevin.tian at intel.com>
---
 drivers/gpu/drm/i915/intel_uncore.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
index d5f39f3..ec6d5ce 100644
--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -719,6 +719,14 @@ hsw_write##x(struct drm_i915_private *dev_priv, off_t reg, u##x val, bool trace)
 	REG_WRITE_FOOTER; \
 }
 
+#define __vgpu_write(x) \
+static void \
+vgpu_write##x(struct drm_i915_private *dev_priv, off_t reg, u##x val, bool trace) { \
+	REG_WRITE_HEADER; \
+	__raw_i915_write##x(dev_priv, reg, val); \
+	REG_WRITE_FOOTER; \
+}
+
 static const u32 gen8_shadowed_regs[] = {
 	FORCEWAKE_MT,
 	GEN6_RPNSWREQ,
@@ -813,6 +821,10 @@ __gen4_write(8)
 __gen4_write(16)
 __gen4_write(32)
 __gen4_write(64)
+__vgpu_write(8)
+__vgpu_write(16)
+__vgpu_write(32)
+__vgpu_write(64)
 
 #undef __chv_write
 #undef __gen8_write
@@ -820,6 +832,7 @@ __gen4_write(64)
 #undef __gen6_write
 #undef __gen5_write
 #undef __gen4_write
+#undef __vgpu_write
 #undef REG_WRITE_FOOTER
 #undef REG_WRITE_HEADER
 
@@ -950,6 +963,13 @@ void intel_uncore_init(struct drm_device *dev)
 		dev_priv->uncore.funcs.mmio_readq  = gen4_read64;
 		break;
 	}
+
+	if (intel_vgpu_active(dev)) {
+		dev_priv->uncore.funcs.mmio_writeb = vgpu_write8;
+		dev_priv->uncore.funcs.mmio_writew = vgpu_write16;
+		dev_priv->uncore.funcs.mmio_writel = vgpu_write32;
+		dev_priv->uncore.funcs.mmio_writeq = vgpu_write64;
+	}
 }
 
 void intel_uncore_fini(struct drm_device *dev)
-- 
1.9.1