[Intel-gfx] [PATCH 2/4] drm/i915/uc: Reserve upper range of GGTT

[Chris Wilson]

Quoting Fernando Pacheco (2019-04-15 23:32:32)
> 
> On 4/9/19 2:41 PM, Chris Wilson wrote:
> > Quoting Fernando Pacheco (2019-04-09 22:31:00)
> >> GuC and HuC depend on struct_mutex for device
> >> reinitialization. Moving away from this dependency
> >> requires perma-pinning the firmware images in GGTT.
> >> The upper portion of the GuC address space has
> >> a sizeable hole (several MB) that is inaccessible
> >> by GuC. Reserve this range within GGTT as it can
> >> comfortably hold GuC/HuC firmware images.
> >>
> >> Signed-off-by: Fernando Pacheco <fernando.pacheco at intel.com>
> >> ---
> >>  drivers/gpu/drm/i915/i915_gem_gtt.c | 25 ++++++++++++++++++++++---
> >>  drivers/gpu/drm/i915/i915_gem_gtt.h |  1 +
> >>  drivers/gpu/drm/i915/intel_guc.h    | 11 +++++++++++
> >>  3 files changed, 34 insertions(+), 3 deletions(-)
> >>
> >> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
> >> index 736c845eb77f..30f294a07e6d 100644
> >> --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
> >> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
> >> @@ -2747,6 +2747,18 @@ int i915_gem_init_ggtt(struct drm_i915_private *dev_priv)
> >>         if (ret)
> >>                 return ret;
> >>  
> >> +       /* Reserve a mappable slot for our lockless uC firmware load */
> >> +       if (USES_GUC(dev_priv)) {
> >> +               ret = drm_mm_insert_node_in_range(&ggtt->vm.mm, &ggtt->uc_fw,
> >> +                                                 GUC_GGTT_FW_SIZE, 0,
> >> +                                                 I915_COLOR_UNEVICTABLE,
> >> +                                                 GUC_GGTT_FW_START,
> >> +                                                 GUC_GGTT_FW_END,
> >> +                                                 DRM_MM_INSERT_LOW);
> > Use drm_mm_reserve_node() as you want an explicit address.
> >
> > We should be able to push this to guc init, with appropriate bailing if
> > something already took the high range.
> 
> I tried pushing this to guc init, but this bailed immediately as there are
> pinnings between the calls to ggtt init and guc init. Did I misinterpret what
> you had in mind?

I was hoping we didn't... No worries, this reservation takes priority
and if that requires a hook here to call into guc so be it.
-Chris