Re: [PATCH v3 7/8] drm/i915: Create vGPU specific write MMIO to reduce traps

Yu, Zhang
2014-12-17T07:30:02Z

On 12/12/2014 9:31 PM, Tvrtko Ursulin wrote:
>
> On 11/13/2014 12:02 PM, Yu Zhang wrote:
>> In the virtualized environment, forcewake operations are not
>> necessory for the driver, because mmio accesses will be trapped
>
> necessary
Thanks.
>
>> 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 running in the VM
>> with Intel GVT-g enhancement.
>>
>> v2:
>> take Chris' comments:
>> - register the mmio hooks in intel_uncore_init()
>> v3:
>> take Daniel's comments:
>> - use macros to assign mmio write functions for vGPU
>>
>> Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
>> Signed-off-by: Jike Song <jike.song@intel.com>
>> Signed-off-by: Kevin Tian <kevin.tian@intel.com>
>> ---
>> drivers/gpu/drm/i915/intel_uncore.c | 16 ++++++++++++++++
>> 1 file changed, 16 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/i915/intel_uncore.c
>> b/drivers/gpu/drm/i915/intel_uncore.c
>> index cae27bb..b76c21d 100644
>> --- a/drivers/gpu/drm/i915/intel_uncore.c
>> +++ b/drivers/gpu/drm/i915/intel_uncore.c
>> @@ -727,6 +727,14 @@ 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,
>> @@ -821,6 +829,10 @@ __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
>> @@ -828,6 +840,7 @@ __gen4_write(64)
>> #undef __gen6_write
>> #undef __gen5_write
>> #undef __gen4_write
>> +#undef __vgpu_write
>> #undef REG_WRITE_FOOTER
>> #undef REG_WRITE_HEADER
>>
>> @@ -939,6 +952,9 @@ void intel_uncore_init(struct drm_device *dev)
>> break;
>> }
>>
>> + if (intel_vgpu_active(dev))
>> + ASSIGN_WRITE_MMIO_VFUNCS(vgpu);
>> +
>> i915_check_and_clear_faults(dev);
>> }
>> #undef ASSIGN_WRITE_MMIO_VFUNCS
>>
>
> Maybe I am missing something obvious, but why are read variants not needed?
Wah. You got me. Guess I missed this during rebase. Thank you, Tvrtko.
>
> Regards,
>
> Tvrtko
>
>
B.R.
Yu