[Intel-gfx] [PATCH 09/10] drm/i915: Reject < 8 byte batches on 830/845

Ville Syrjälä ville.syrjala at linux.intel.com
Mon Dec 14 09:29:19 PST 2015

On Mon, Dec 14, 2015 at 05:07:50PM +0000, Chris Wilson wrote:
> On Mon, Dec 14, 2015 at 06:23:48PM +0200, ville.syrjala at linux.intel.com wrote:
> > From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > 
> > We use MI_BATCH_BUFFER on 830/845, which means we need to know
> > the batch length. If the user passes a bad batch length (< 8)
> > the results is most likely a GPU hang. Rejct such batches.
> > 
> > Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
> Though, do you then remove the discrepancy in the next MI_BB_START
> patch?

Yeah, I figured I'd still keep this in case the user passes in
bogus batch_len, but now that I think about it, there's no way for
values in the 1-7 range to reach us here due to the earlier 
'batch_len & 7' check, and 0 would get replaced by the obj size.
I guess we could drop this patch then.

Ville Syrjälä
Intel OTC

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