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

[Daniel Vetter]

On Wed, Oct 22, 2014 at 08:27:50PM +0800, Yu, Zhang wrote:
> 
> 
> On 10/22/2014 12:40 AM, Daniel Vetter wrote:
> >On Thu, Oct 16, 2014 at 02:24:27PM +0800, Yu Zhang wrote:
> >>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.
> >>
> >>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;
> >
> >Someone should write a cool macro which uses prepocessor string
> >concatenation so that we can compress this all to
> >
> >	ASSIGN_WRITE_MMIO_VFUNCS(vgpu)
> >
> >Then throw in an ASSIGN_READ_MMIO_VFUNC which looks similarly and this
> >might actually be pretty. Just an idea for some follow-up cleanup.
> >-Daniel
> >
> Thanks Daniel.
> Do you mean something like this:
> #define ASSIGN_WRITE_MMIO_VFUNCS(x) \
> do {	\
> 	dev_priv->uncore.funcs.mmio_writeb  = x##_write8;	\
> 	dev_priv->uncore.funcs.mmio_writew  = x##_write16;	\
> 	dev_priv->uncore.funcs.mmio_writel  = x##_write32;	\
> 	dev_priv->uncore.funcs.mmio_writeq  = x##_write64;	\
> } while (0)
> 
> and then we can use ASSIGN_WRITE_MMIO_VFUNCS(hsw) for hsw and
> ASSIGN_WRITE_MMIO_VFUNCS(vgpu) for vgpu, etc?

Yup. Plus the version for assigning READ vfuncs (on many platforms they
don't match up). Probably best if you do this conversion as a prep patch
before the vgt series so that I can merge it right away.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch