Re: [PATCH 8/8] drm/i915: Support alias ppgtt in VM if ppgtt is enabled

[Jike Song <jike.song@intel.com>]

On 09/19/2014 04:25 PM, Chris Wilson wrote:
>
> This should be moved to sanitize_enable_ppgtt(), probably by expanding
> HAS_PPGTT(), e.g.:
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 07dafa2c2d8c..b1fa13942d14 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -2139,8 +2139,6 @@ struct drm_i915_cmd_table {
>
>   #define HAS_HW_CONTEXTS(dev)   (INTEL_INFO(dev)->gen >= 6)
>   #define HAS_LOGICAL_RING_CONTEXTS(dev) (INTEL_INFO(dev)->gen >= 8)
> -#define HAS_ALIASING_PPGTT(dev)        (INTEL_INFO(dev)->gen >= 6)
> -#define HAS_PPGTT(dev)         (INTEL_INFO(dev)->gen >= 7 && !IS_GEN8(dev))
>   #define USES_PPGTT(dev)                (i915.enable_ppgtt)
>   #define USES_FULL_PPGTT(dev)   (i915.enable_ppgtt == 2)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
> index a234446a8678..3bea0bdfd276 100644
> --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
> @@ -35,13 +35,23 @@ static void chv_setup_private_ppat(struct drm_i915_private *dev_priv);
>
>   static int sanitize_enable_ppgtt(struct drm_device *dev, int enable_ppgtt)
>   {
> -       if (enable_ppgtt == 0 || !HAS_ALIASING_PPGTT(dev))
> +       bool has_aliasing_ppgtt;
> +       bool has_full_ppgtt;
> +
> +       has_aliasing_ppgtt = INTEL_INFO(dev)->gen >= 6;
> +       has_full_ppgtt = INTEL_INFO(dev)->gen >= 7;
> +       if (IS_GEN8(dev))
> +               has_full_ppgtt = false; /* XXX why? */
> +       if (intel_vgpu_active(dev))
> +               has_full_ppgtt = false; /* emulation is too hard */
> +
> +       if (enable_ppgtt == 0 || !has_aliasing_ppgtt)
>                  return 0;
>
>          if (enable_ppgtt == 1)
>                  return 1;
>
> -       if (enable_ppgtt == 2 && HAS_PPGTT(dev))
> +       if (enable_ppgtt == 2 && has_full_ppgtt)
>                  return 2;
>
>   #ifdef CONFIG_INTEL_IOMMU
> @@ -59,7 +69,7 @@ static int sanitize_enable_ppgtt(struct drm_device *dev, int enable_ppgtt)
>                  return 0;
>          }
>
> -       return HAS_PPGTT(dev) ? 2 : HAS_ALIASING_PPGTT(dev) ? 1 : 0;
> +       return has_full_ppgtt ? 2 : has_aliasing_ppgtt ? 1 : 0;
>   }

Thanks for the demo. Currently sanitize_enable_ppgtt() is called by i915_gem_gtt_init(), before
intel_check_vgpu().

I'm trying to detect VGPU as early as possible, maybe between intel_detect_pch() and intel_uncore_init(),
using bare readq/readw instead of I915_READxx.


>
> -Chris
>
--
Thanks,
Jike