On Mon, Feb 12, 2018 at 05:37:56PM +0000, Chris Wilson wrote: > Quoting Ville Syrjälä (2018-02-12 17:30:52) > > On Sat, Feb 10, 2018 at 09:43:38PM +0000, Chris Wilson wrote: > > > On ctg/ilk, for whatever reason, MI_STORE_DWORD is a privileged operation > > > so we must request a SECURE batch. > > > > IIRC ctg supposedly introduced some form of ppgtt. Isn't that the > > reason? > > > > Hmm. Now I wonder how anything works on these platforms. Should the > > batch itself be executed via ppgtt if it's non-secure? Maybe the hw > > has a fallback mechanism of some sort to execute via ggtt if ppgtt > > isn't enabled... > > > > ppgtt enable bit: > > "When this bit is clear, all memory accesses will be completed using the > > GGTT. Privileged memory protections will not be enforced (it is > > acceptable for a non-secure batch buffer to access GGTT space)" > > > > OK. That seems to confirm that part of the theory. > > > > For pre-ctg the spec says: > > "Although Buffer Security Indicator is implemented, there is no usage > > model for it and it need not be validated." > > > > So I'm thinking we should never set the non-secure bit on these old > > platforms. > > That does open a large can of worms with the ability to write any > register from userspace or manipulate the pagetables; i.e. requires the > cmdparser. The usage model has been such that very few commands are > affected; certainly no one [else] has noticed (afaik). I suppose. I can't find any notes about this being wrong in the gen2/3 docs. And the gen4 quote just says "need not be validated" after all so I suppose it doesn't necessarily mean it wasn't validated. And I guess we should have found out long ago if it's hopelessly broken. Patch is Reviewed-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> -- Ville Syrjälä Intel OTC _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
