So when reviewing Michel's patch I've noticed a few things and cleaned
them up:
- The early checks in ppgtt_release are now redundant: The inactive
  list should always be empty now, so we can ditch these checks. Even
  for the aliasing ppgtt (though that's a different confusion) since
  we tear that down after all the objects are gone.
- The ppgtt handling functions are splattered all over. Consolidate
  them in i915_gem_gtt.c, give them OCD prefixes and add wrappers for
  get/put.
- There was a bit a confusion in ppgtt_release about whether it cares
  about the active or inactive list. It should care about them both,
  so augment the WARNINGs to check for both.

There's still create_vm_for_ctx left to do, put that is blocked on the
removal of ppgtt->ctx. Once that's done we can rename it to
i915_ppgtt_create and move it to its siblings for handling ppgtts.

v2: Move the ppgtt checks into the inline get/put functions as
suggested by Chris.

v3: Inline the now redundant ppgtt local variable.

Cc: Michel Thierry <michel.thierry@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NMichel Thierry <michel.thierry@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

sanitize_enable_ppgtt is the function that checks all the conditions,
honoring a forced ppgtt status or doing auto-detect as necessary.  Just
make sure it returns the right value in all cases and use that in the
macros instead of the confusing intel_enable_ppgtt() function.
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NRodrigo Vivi <rodrigo.vivi@intel.com>
[danvet: Don't reenable full ppgtt through the backdoor.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This adds support for a write-enable bit in the entry of GTT.
This is handled via a read-only flag in the GEM buffer object which
is then used to see how to set the bit when writing the GTT entries.
Currently by default the Batch buffer & Ring buffers are marked as read only.

v2: Moved the pte override code for read-only bit to 'byt_pte_encode'. (Chris)
    Fixed the issue of leaving 'gt_old_ro' as unused. (Chris)

v3: Removed the 'gt_old_ro' field, now setting RO bit only for Ring Buffers(Daniel).

v4: Added a new 'flags' parameter to all the pte(gen6) encode & insert_entries functions,
    in lieu of overloading the cache_level enum (Daniel).

v5: Removed the superfluous VLV check & changed the definition location of PTE_READ_ONLY flag (Imre)
Reviewed-by: NImre Deak <imre.deak@intel.com>
Signed-off-by: NAkash Goel <akash.goel@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Up until now, contexts had one (and only one) backing object that was
used by the hardware to save/restore render ring contexts (via the
MI_SET_CONTEXT command). Other rings did not have or need this, so
our i915_hw_context struct had a 1:1 relationship with a a real HW
context.

With Logical Ring Contexts and Execlists, this is not possible anymore:
all rings need a backing object, and it cannot be reused. To prepare
for that, rename our contexts to the more generic term intel_context.

No functional changes.
Signed-off-by: NOscar Mateo <oscar.mateo@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

In the upcoming patches we plan to break the correlation between
engine command streamers (a.k.a. rings) and ringbuffers, so it
makes sense to refactor the code and make the change obvious.

No functional changes.
Signed-off-by: NOscar Mateo <oscar.mateo@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Ignore the cache bits in PPAT and just set the snoop bit where
appropriate. BDW WB is mapped to snooped access, while all other
modes are mapped to non-snooped access.

The hardware supposedly ignores everything except the snoop bit
in the PPAT entries.

Additionally the hardware actually enforces snooping for all
page table accesses, and thus the snoop bit is ignored for PDEs.

v2: Rebased on top of the bdw resume fix to reload the ppat entries.

v3: Rebase on top of the i915_gem_gtt.h header extraction.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com> (v1)
Acked-by: NBen Widawsky <ben@bwidawsk.net>
Reviewed-by: NRafael Barbalho <rafael.barbalho@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This file contains all necessary defines, prototypes and typesdefs for
manipulating GEN graphics address translation (this does not include the
legacy AGP driver)

Reiterating the comment in the header,
"Please try to maintain the following order within this file unless it
makes sense to do otherwise. From top to bottom:
1. typedefs
2. #defines, and macros
3. structure definitions
4. function prototypes

Within each section, please try to order by generation in ascending
order, from top to bottom (ie. GEN6 on the top, GEN8 on the bottom)."

I've made some minor cleanups, and fixed a couple of typos while here -
but there should be no functional changes.

The purpose of the patch is to reduce clutter in our main header file,
making room for new growth, and make documentation of our interfaces
easier by splitting things out.

With a little more work, like making i915_gtt a pointer, we could
potentially completely isolate this header from i915_drv.h. At the
moment however, I don't think it's worth the effort.

Personally, I would have liked to put the PTE encoding functions in this
file too, but I didn't want to rock the boat too much.

A similar patch has been in use on my machine for some time. This exact
patch though has only been compile tested.
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>