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). -Chris _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
