[PATCH v2] drm/i915/gvt: Fix crash after request->hw_context change

[Chris Wilson]

Quoting Zhenyu Wang (2018-05-21 09:17:52)
> When we do shadowing, workload's request might not be allocated yet,
> so we still require shadow context's object. And when complete workload,
> delay to zero workload's request pointer after used for update guest context.
> 
> v2: Move request alloc earlier as already try to track shadow status
> depending on request state, which also facilitate to use request->hw_context
> for target engine context reference.
> 
> Fixes: 1fc44d9b1afb ("drm/i915: Store a pointer to intel_context in i915_request")
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> Cc: Zhi Wang <zhi.a.wang at intel.com>
> Cc: Weinan Li <weinan.z.li at intel.com>
> Signed-off-by: Zhenyu Wang <zhenyuw at linux.intel.com>

Looks like it's applying the principles we discussed to avoid
chasing gem_context to get at the pinned intel_context,
Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>

Thanks for the fixup!
-Chris