On Tue, Sep 17, 2013 at 04:48:50PM -0700, Ben Widawsky wrote:
> On Wed, Sep 18, 2013 at 12:33:32AM +0100, Chris Wilson wrote:
> > On Tue, Sep 17, 2013 at 04:14:43PM -0700, Ben Widawsky wrote:
> > > On Tue, Sep 17, 2013 at 09:55:35PM +0100, Chris Wilson wrote:
> > > > On Tue, Sep 17, 2013 at 10:01:33AM -0700, Ben Widawsky wrote:
> > > > > @@ -1117,8 +1109,13 @@ i915_gem_do_execbuffer(struct drm_device *dev, void *data,
> > > > > * batch" bit. Hence we need to pin secure batches into the global gtt.
> > > > > * hsw should have this fixed, but let's be paranoid and do it
> > > > > * unconditionally for now. */
> > > > > - if (flags & I915_DISPATCH_SECURE && !batch_obj->has_global_gtt_mapping)
> > > > > - i915_gem_gtt_bind_object(batch_obj, batch_obj->cache_level);
> > > > > + if (flags & I915_DISPATCH_SECURE &&
> > > > > + !batch_obj->has_global_gtt_mapping) {
> > > > > + const struct i915_address_space *ggtt = obj_to_ggtt(batch_obj);
> > > > > + struct i915_vma *vma = i915_gem_obj_to_ggtt(batch_obj);
> > > > > + BUG_ON(!vma);
> > > > > + ggtt->bind_vma(vma, batch_obj->cache_level, GLOBAL_BIND);
> > > > > + }
> > > >
> > > > The issue here is that if we don't set the USE_PPGTT/USE_SECURE flag in
> > > > the dispatch, the CS will use the GGTT (hence our binding) but so we
> > > > then need to use the GGTT offset for the dispatch as well.
> > > >
> > > > Is that as concisely as we can write bind_to_ggtt? :(
> > > > -Chris
> > > >
> > >
> > > Resuming the conversation started on irc... what do you want from me?
> >
> > I think we need to pass the ggtt offset to dispatch for
> > I915_DISPATCH_SECURE -- which offset to use might even depend upon the
> > implementation and hw generation in intel_ringbuffer.c. But at the very
> > least, I think SNB/IVB will be executing the wrong address come full
> > ppgtt.
> >
> > dev_priv->ggtt.base.bind_vma(i915_gem_obj_to_ggtt(batch_obj),
> > batch_obj->cache_level,
> > GLOBAL_BIND);
> >
> > #define i915_vm_bind(vm__, vma__, cache_level__, flags__) \
> > (vm__)->bind_vma((vma__), (cache_level__), (flags__))
> >
> > i915_vm_bind(&dev_priv->ggtt.base,
> > i915_gem_obj_to_ggtt(batch_obj),
> > batch_obj->cache_level,
> > GLOBAL_BIND);
> > -Chris
> >
>
> I915_DISPATCH_SECURE is a special case. If we see the flag, we look up
> the GGTT offset as opposed to the offset in the VM being used at
> execbuf. We can either bind the batchbuffer into both the PPGTT, and
> GGTT, or it's only even in the GGTT - in either case, we'll have to have
> done the bind (and found space in the drm_mm). It just seems like this
> is duplicating the already existing i915_gem_object_bind_to_vm code
> that's in place.
>
> Sorry if I am not following what you're asking. I'm just failing to see
> a problem, or maybe you're just trying to solve problems that I haven't
> yet conceived; or solved in a different way. It's pretty darn hard to
> discuss this given the piecemeal nature of the thing.
The code does
exec_start = i915_gem_obj_offset(batch_obj, vm) +
args->batch_start_offset;
exec_len = args->batch_len;
...
ret = ring->dispatch_execbuffer(ring,
exec_start, exec_len,
flags);
if (ret)
goto err;
So we lookup the address of the batch buffer in the wrong vm for
I915_DISPATCH_SECURE.
-Chris
--
Chris Wilson, Intel Open Source Technology Centre
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