Re: [PATCH] drm/i915: Fix up the vma aliasing ppgtt binding

Daniel Vetter
2015-05-04T08:47:11Z

On Fri, Apr 24, 2015 at 12:55:57PM +0100, Chris Wilson wrote:
> On Fri, Apr 24, 2015 at 12:14:17PM +0100, Chris Wilson wrote:
> > On Mon, Apr 20, 2015 at 09:04:05AM -0700, Daniel Vetter wrote:
> > > Currently we have the problem that the decision whether ptes need to
> > > be (re)written is splattered all over the codebase. Move all that into
> > > i915_vma_bind. This needs a few changes:
> > > - Just reuse the PIN_* flags for i915_vma_bind and do the conversion
> > > to vma->bound in there to avoid duplicating the conversion code all
> > > over.
> > > - We need to make binding for EXECBUF (i.e. pick aliasing ppgtt if
> > > around) explicit, add PIN_USER for that.
> > > - Two callers want to update ptes, give them a PIN_UPDATE for that.
> > >
> > > Of course we still want to avoid double-binding, but that should be
> > > taken care of:
> > > - A ppgtt vma will only ever see PIN_USER, so no issue with
> > > double-binding.
> > > - A ggtt vma with aliasing ppgtt needs both types of binding, and we
> > > track that properly now.
> > > - A ggtt vma without aliasing ppgtt could be bound twice. In the
> > > lower-level ->bind_vma functions hence unconditionally set
> > > GLOBAL_BIND when writing the ggtt ptes.
> > >
> > > There's still a bit room for cleanup, but that's for follow-up
> > > patches.
> > >
> > > v2: Fixup fumbles.
> > >
> > > v3: s/PIN_EXECBUF/PIN_USER/ for clearer meaning, suggested by Chris.
> > >
> > > Cc: Chris Wilson <chris@chris-wilson.co.uk>
> > > Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> >
> > I'm getting lots of GPU hangs from this patch...

Oops, I've considered the vma_unbind case but then totally forgot that a
vma can survive over execbuf. Can you please wrap this into a proper
commit message with sob?

> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index 91aade7..e3841f8 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -3066,8 +3066,8 @@ int i915_vma_unbind(struct i915_vma *vma)
> }
>
> trace_i915_vma_unbind(vma);
> -
> vma->vm->unbind_vma(vma);
> + vma->bound = 0;
>
> list_del_init(&vma->mm_list);
> if (i915_is_ggtt(vma->vm)) {
> @@ -3588,7 +3588,6 @@ search_free:
> if (ret)
> goto err_remove_node;
>
> - trace_i915_vma_bind(vma, flags);
> ret = i915_vma_bind(vma, obj->cache_level, flags);
> if (ret)
> goto err_finish_gtt;
> diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> index cfdc8c6..45d74da 100644
> --- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> +++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> @@ -1563,9 +1563,7 @@ i915_gem_do_execbuffer(struct drm_device *dev, void *data,
> * be in ggtt still end up in the aliasing ppgtt. remove
> * this check when that is fixed.
> */
> - if (USES_FULL_PPGTT(dev))
> - dispatch_flags |= I915_DISPATCH_SECURE;
> -
> + dispatch_flags |= I915_DISPATCH_SECURE;

Unrelated hunk?

> exec_start = 0;
> }
>
> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
> index 9e06180..bbeb6c3 100644
> --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
> @@ -1949,8 +1949,6 @@ static void i915_ggtt_bind_vma(struct i915_vma *vma,
>
> BUG_ON(!i915_is_ggtt(vma->vm));
> intel_gtt_insert_sg_entries(vma->ggtt_view.pages, entry, flags);
> -
> - vma->bound |= GLOBAL_BIND;

Hm, why remove this? I added this to avoid double-binding on platforms
where one implies the other binding type. Maybe should have been a bit
more consistent with bound |= GLOBAL_BIND | LOCAL_BIND.
-Daniel

> }
>
> static void i915_ggtt_clear_range(struct i915_address_space *vm,
> @@ -2813,9 +2811,12 @@ i915_get_ggtt_vma_pages(struct i915_vma *vma)
> int i915_vma_bind(struct i915_vma *vma, enum i915_cache_level cache_level,
> u32 flags)
> {
> - u32 bind_flags = 0;
> + u32 bind_flags;
> int ret;
>
> + if (WARN_ON(flags == 0))
> + return -EINVAL;
> +
> if (vma->vm->allocate_va_range) {
> trace_i915_va_alloc(vma->vm, vma->node.start,
> vma->node.size,
> @@ -2834,6 +2835,7 @@ int i915_vma_bind(struct i915_vma *vma, enum i915_cache_level cache_level,
> return 0;
> }
>
> + bind_flags = 0;
> if (flags & PIN_GLOBAL)
> bind_flags |= GLOBAL_BIND;
> if (flags & PIN_USER)
> @@ -2844,10 +2846,11 @@ int i915_vma_bind(struct i915_vma *vma, enum i915_cache_level cache_level,
> else
> bind_flags &= ~vma->bound;
>
> - if (bind_flags)
> + if (bind_flags) {
> + trace_i915_vma_bind(vma, bind_flags);
> vma->vm->bind_vma(vma, cache_level, bind_flags);
> -
> - vma->bound |= bind_flags;
> + vma->bound |= bind_flags;
> + }
>
> return 0;
> }
>
> --
> Chris Wilson, Intel Open Source Technology Centre

--
Daniel Vetter
Software Engineer, Intel Corporation