[Intel-gfx] [PATCH] drm/i915: Disable read only ppgtt support for gen11

[Chris Wilson]

Quoting Mika Kuoppala (2019-04-11 09:30:34)
> On gen11 writing to read only ppgtt page causes a gpu hang.
> This behaviour is different than with previous gen where
> read only ppgtt access is supported. On those, the write
> is just dropped without visible side effects.
> 
> Disable ro ppgtt support on gen11 until a solution can
> be found to bring it into line with its predecessors.
> 
> References: HSDES#1807136187
> References: https://bugzilla.freedesktop.org/show_bug.cgi?id=108569
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Signed-off-by: Mika Kuoppala <mika.kuoppala at linux.intel.com>
Acked-by: Chris Wilson <chris at chris-wilson.co.uk>

Lets see if I remembered to stick those vm->has_read_only checks
everywhere we needed them (and remembered to exercise them -- a bit of a
catch 22, if I forgot the check, I probably forgot the test as well).

Thanks,
-Chris