Freeing a request triggers the destruction of the context. This needs to
occur after all objects are themselves unbound from the context, and so
the free request needs to occur after the object release during retire.

This tidies up

commit e2078043
Author: Ben Widawsky <ben@bwidawsk.net>
Date:   Fri Dec 6 14:11:22 2013 -0800

    drm/i915: Defer request freeing

by simply swapping the order of operations rather than introducing
further complexity - as noted during review.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Ben Widawsky <ben@bwidawsk.net>
Reviewed-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

The initialized flag is used to specify a context has been initialized
and it's context is safe to load, ie. the 3d state is setup properly.
With full PPGTT, we emit the address space loads during context switch
and this currently marks a context as initialized. With full PPGTT
patches, if a client first emits a batch to !RCS, then later, RCS, the
code will mistake the context as initialized and try to reload an
uninitialized context.

1. context 1 blit // context marked as initialized, but isn't
2. context 1 render // loads random state from step 2

It is really easy to hit this with a planned upcoming patch which makes
default context reuse possible.

NOTE: This should only effect full PPGTT branches, ie. current
drm-intel-nightly.

Thanks to Chris for helping me track this down.

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
[danvet: Simplify the failure scenario in the commit message according
to Chris' review a bit.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This was an accidental "ABI" change introduced during PPGTT:

commit 0eea67eb
Author: Ben Widawsky <ben@bwidawsk.net>
Date:   Fri Dec 6 14:11:19 2013 -0800

    drm/i915: Create a per file_priv default context

The failure test application actually tests the return type. The other
option is to simply change the test.
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

A regression in the topic/ppgtt branch introduce in

commit 87d60b63
Author: Ben Widawsky <ben@bwidawsk.net>
Date:   Fri Dec 6 14:11:29 2013 -0800

    drm/i915: Add PPGTT dumper

The issue is that we're missing the definitions for the seq_file
functions and hence compilation fails.

v2: Just include the right header instead of splattering #ifdefs all
over the place (Chris).

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reported-by: Nkbuild test robot <fengguang.wu@intel.com>
Reported-by: NAntti Koskipaa <antti.koskipaa@linux.intel.com>
Cc: Ben Widawsky <ben@bwidawsk.net>
Reviewed-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Without this fix the ioctls silently succeeded (but actually did
nothing).

It makes all the code which calls into this function way too confusing.

v2: Fix destroy IOCTL as well

v3: Clarify the other two callers of i915_gem_context_get() to never
check for NULL. (Mika)

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=72903Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Testcase: igt/gem_ctx_exec/basic
[danvet: Fix up the commit message and actually bother to mention the
testcase this fixes.]
Reviewed-by: NMika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This means something different and is only relevant for gen6 and the
reason why we cant use anything else than aliasing ppgtt there.

Note that the currently implemented logic for secure batches is
broken: Userspace wants the buffer both in ppgtt (for self-referencing
relocations) and in ggtt (for priveledge operations).

This is the same issue the command parser is also facing.
Unfortunately our coverage for corner-cases of self-referencing
batches is spotty.

Note that this will break vsync'ed Xv and DRI2 copies.
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Doesn't make sense. Spotted while fixing an issue Chris
noticed in the same area.
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This reverts commit 4fe9adbc.

The patch completely lacks a detailed explanation of what exactly
blows up and how, so is insufficiently justified as a band-aid.

Otoh the justification as a safety measure against userspace botching
up relocations is also fairly weak: If we want real project we need to
at least make the gab big enough that the gpu doesn't scribble over
more important stuff. With 4k screens that would be 32MB.

Also I think this would be much better in conjunction with a (debug)
switch to disable our use of the scratch page.

Hence revert this.
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This reverts the abi-change from

commit 67e3d297
Author: Ben Widawsky <ben@bwidawsk.net>
Date:   Fri Dec 6 14:11:01 2013 -0800

    drm/i915: Permit contexts on all rings

We don't actually need this, only the internal changes to allow
contexts on all rings for the purpose of ppgtt switching are required.
And I'm not sure whether this is the right thing to do given some of
the hw features in the pipeline.

Also, new abi needs userspace patches as a proof-of-need, which is
completely lacking here.
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

At least for now userspace has no business at all to know that we
switch address spaces around. For any need it has to know whether hw
ppgtt is enabled (e.g. to set bits in MI commands correctly) it can
inquire the existing ppgtt param.

v2: Avoid ternary operator precedence fail (Chris).
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Especially with ppgtt this kinda stopped making sense. And if we
indeed need this to hack around an issue, we need something that also
works for non-root.
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Dump the aliasing PPGTT with it. The aliasing PPGTT should actually
always be empty.

TODO: Broadwell. Since we don't yet use full PPGTT on Broadwell, not
having the dumper is okay.
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Originally this commit message said:
Now that do_switch does the mm switch, and we always enable the aliasing
PPGTT, and contexts at the same time, there is no need to continue doing
this during PPGTT enabling.

Since originally writing the patch however, I introduced the concept of
synchronous mm switching (using MMIO). Since this is generally not
recommended in the spec (for reasons unknown), I've isolated its usage
as much as possible. As such the "extraneous" switch only ever will
occur when we have full PPGTT.
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

As with processes which run on the CPU, the goal of multiple VMs is to
provide process isolation. Specific to GEN, there is also the ability to
map more objects per process (2GB each instead of 2Gb-2k total).

For the most part, all the pipes have been laid, and all we need to do
is remove asserts and actually start changing address spaces with the
context switch. Since prior to this we've converted the setting of the
page tables to a streamed version, this is quite easy.

One important thing to point out (since it'd been hotly contested) is
that with this patch, every context created will have it's own address
space (provided the HW can do it).

v2: Disable BDW on rebase

NOTE: I tried to make this commit as small as possible. I needed one
place where I could "turn everything on" and that is here. It could be
split into finer commits, but I didn't really see much point.

Cc: Eric Anholt <eric@anholt.net>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

I need the tricky do_switch fix before I can merge the final piece of
the ppgtt enabling puzzle. Otherwise the conflict will be a real pain
to resolve since the do_switch hunk from -fixes must be placed at the
exact right place within a hunk in the next patch.

Conflicts:
	drivers/gpu/drm/i915/i915_gem_context.c
	drivers/gpu/drm/i915/i915_gem_execbuffer.c
	drivers/gpu/drm/i915/intel_display.c
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This is primarily a band aid for an unexplainable error in
gem_reloc_vs_gpu/forked-faulting-reloc-thrashing. Essentially as soon as
a relocated buffer (which had a non-zero presumed offset) moved to
offset 0, something goes bad. Since I have been unable to solve this,
and potentially this is a good thing to do anyway, since many things can
accidentally write to offset 0, why not?
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

It's quite common for an object to simply be on the inactive list (and
not unbound) when we want to free the context. This of course happens
with lazy unbinding. Simply, this is needed when an object isn't fully
unbound but we want to free one VMA of the object, for whatever reason.

NOTE: The aliasing PPGTT is not a proper VM, so it needs special casing.

This addresses the fixup requirement mentioned in:
drm/915: Better reset handling for contexts

In the flink, and dmabuf case, we can't assert that the object isn't
still active. To keep it more generic, just check the vma's link in the
object vma list. If we wanted to do a better job, we could track last
seqno (and active) per VMA. It was decided not to do this in the last
iteration. Unfortunately this means the assertion can miss real bugs
when using flink/dmabuf.

v2: Use the newer introduced i915_gem_evict_vm(). Note that handling the
aliasing PPGTT is special.
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

With context destruction, we always want to be able to tear down the
underlying address space. This is invoked on the last unreference to the
context which could happen before we've moved all objects to the
inactive list. To enable a clean tear down the address space, make sure
to process the request free lastly.

Without this change, we cannot guarantee to we don't still have active
objects in the VM.

As an example of a failing case:
CTX-A is created, count=1
CTX-A is used during execbuf
	does a context switch count = 2
	and add_request count = 3
CTX B runs, switches, CTX-A count = 2
CTX-A is destroyed, count = 1
retire requests is called
	free_request from CTX-A, count = 0 <--- free context with active object

As mentioned above, by doing the free request after processing the
active list, we can avoid this case.
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

We need to have the address space when reserving space for the objects.
Since the address space and context are tied together, and reserve
occurs before context switch (for good reason), we must lookup our
context earlier in the process.

This leaves some room for optimizations where we no longer need to use
ctx_id in certain places. This will be addressed in a subsequent patch.

Important tricky bit:
Because slow relocations during execbuffer drop struct_mutex

Perhaps it would be best to acquire the reference when we get the
context, but I'll save that for another day (note I have written the
patch before, and I found the changes required to be uglier than this).

Note that since we currently access everything via context id, and not
the data structure this is fine, though not desirable. The next change
attempts to get the context only once via the context ID idr lookup, and
as such, the following can happen:

CTX-A is created, refcount = 1
CTX-A execbuf, mutex dropped
close IOCTL called on CTX-A, refcount = 0
CTX-A resumes in execbuf.

v2: Rebased on top of
commit b6359918
Author: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Date:   Wed Oct 30 15:44:16 2013 +0200

    drm/i915: add i915_get_reset_stats_ioctl

v3: Rebased on top of
commit 25b3dfc8
Author: Mika Westerberg <mika.westerberg@linux.intel.com>
Date:   Tue Nov 12 11:57:30 2013 +0200

Author: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Date:   Tue Nov 26 16:14:33 2013 +0200

    drm/i915: check context reset stats before relocations
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

To simplify the codepaths somewhat, we can simply always create a
context. Contexts already keep hangstat information. This prevents us
from having to differentiate at other parts in the code.

There is allocation overhead, but it should not be measurable.
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Every file will get it's own context, and we use this context instead of
the default context. The default context still exists for future
shrinker usage as well as reset handling.

v2: Updated to address Mika's recent context guilty changes
Some more changes around this come up in later patches as well.

v3: Use a fake context to avoid allocation for the !HAS_HW_CONTEXT case.
I've tried the alternatives. This looks the best to me.
Removed hangstat stuff from v2 - for a separate patch
Demote failed PPGTT set to DRM_DEBUG_DRIVER since it can now be invoked
easily from userspace.
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

We have a default context which suits the aliasing PPGTT well. Tie them
together so it looks like any other context/PPGTT pair. This makes the
code cleaner as it won't have to special case aliasing as often.

The patch has one slightly tricky part in the default context creation
function. In the future (and on aliased setup) we create a new VM for a
context (potentially). However, if we have aliasing PPGTT, which occurs
at this point in time for all platforms GEN6+, we can simply manage the
refcounting to allow things to behave as normal. Now is a good time to
recall that the aliasing_ppgtt doesn't have a real VM, it uses the GGTT
drm_mm.
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

In following with the old restore code, we must now restore ever PPGTT's
PDEs, since they aren't proper GEM ojbects.

v2: Rebased on BDW. Only do restore pdes for gen6 & 7
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

We won't be calling enable() for all PPGTTs. We do need to write PDEs
for all PPGTTs however. By moving the writing to init (which is called
for all PPGTTs) we should accomplish this.

ADD NOTE ABOUT PDE restore

TODO: Eventually, we should allocate the page tables on demand.

v2: Rebased on BDW. Only do PDEs for pre-gen8
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Pretty straightforward so far except for the bit about the refcounting.
The PPGTT will potentially be shared amongst multiple contexts. Because
contexts themselves have a refcounted lifecycle, the easiest way to
manage this will be to refcount the PPGTT. To acheive this, we piggy
back off of the existing context refcount, and will increment and
decrement the PPGTT refcount with context creation, and destruction.

To put it more clearly, if context A, and context B both use PPGTT 0, we
can't free the PPGTT until both A, and B are destroyed.

Note that because the PPGTT is permanently pinned (for now), it really
just matters for the PPGTT destruction, as opposed to making space under
memory pressure.
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This patch consolidates the way in which we handle the various supported
PPGTT by module parameter in addition to what the hardware supports. It
strives to make doing the right thing in the code as simple as possible,
with the USES_ macros.

I've opted to add the full PPGTT argument simply so one can see how I
intend to use this function. It will not/cannot be used until later.
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Rearrange the initialization code to try to special case the aliasing
PPGTT less, and provide usable interfaces for the general case later.
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

I've found this by accident. The docs don't really come out and say you
need to do this. What the docs do tell you is you need to flush the TLBs
before you set the PP_DIR_BASE, and that the RCS will invalidate its
TLBs upon setting the new PP_DIR_BASE. It makes no such comment about
any of the other rings.

Empirically, this indeed fixes a really obvious bug whereby the batches
being sent to the blitter were not executing (we were executing the
HSWP somehow instead).

NOTE: This should make no difference with the current code. It only
applies when we start using multiple VMs.

NOTE2: HSW appears to be immune to this.
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

The docs seem to suggest this is the appropriate method (though it
doesn't say so outright). In other words, we probably should have done
this before. We certainly must do this for switching VMs on the fly,
since synchronizing the rings to MMIO updates isn't acceptable.

v2:
Make the reset code actually work for all rings. Note that this was
fixed in subsequent commits, but was indeed broken for this commit.

Add a posting read to the reset case. It probably should have existed
before hand, but since we have no failures; there is no reason to make
it a separate commit.

Make IS_GEN6 not use the ring because I am seeing crashes when using it.
It is a bit of a hack in this patch, it will get fixed up in a couple of
patches.
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

In order to do the full context switch with address space, it's
convenient to have a way to switch the address space. We already have
this in our code - just pull it out to be called by the context switch
code later.

v2: Rebased on BDW support. Required adding BDW.
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

The patch before this changed the way in which we allocate space for the
PPGTT PDEs. It began carving out the PPGTT PDEs (which live in the
Global GTT) from the GGTT's drm_mm. Prior to that patch, the PDEs were
hidden from the drm_mm, and therefore could never fail to be allocated.

In unfortunate cases, the drm_mm may be full when we want to allocate
the space. This can technically occur whenever we try to allocate, which
happens in two places currently. Practically, it can only really ever
happen at GPU reset.

Later, when we allocate more PDEs for multiple PPGTTs this will
potentially even more useful.
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

When PPGTT support was originally enabled, it was only designed to
support 1 PPGTT. It therefore made sense to simply hide the GGTT space
required to enable this from the drm_mm allocator.

Since we intend to support full PPGTT, which means more than 1, and they
can be created and destroyed ad hoc it will be required to use the
proper allocation techniques we already have.

The first step here is to make the existing single PPGTT use the
allocator.

The astute observer will notice that we are reserving space in the GGTT
for the PDEs for the lifetime of the address space, and would be right
to question whether or not this is a good idea. It does not make a
difference with this current patch only the aliasing PPGTT (indeed the
PDEs should still be hidden from the shrinker). For the future, we are
allocating from top to bottom to avoid using the precious "gtt
space" The GGTT space at that point should only be used for scanout, HW
contexts, ringbuffers, HWSP, PDEs, and a couple of other small buffers
(potentially) used by the kernel. Everything else should be mapped into
a PPGTT. To put the consumption in more tangible terms, it takes
approximately 4 sets of PDEs to equal one 19x10 framebuffer (with no
fancy stride or alignment constraints). 3/4 of the total [average] GGTT
can be used for PDEs, and hopefully never touch the 1/4 that the
framebuffer needs.

The astute, and persistent observer might ask about the page tables
which are also pinned for the address space. This waste is unfortunate.
We use 2MB of memory per address space. We leave wrapping the PDEs as a
real GEM object as a TODO.

v2: Align PDEs to 64b in GTT
Allocate the node dynamically so we can use drm_mm_put_block
Now tested on IGT
Allocate node at the top to avoid fragmentation (Chris)

v3: Use Chris' top down allocator

v4: Embed drm_mm_node into ppgtt struct (Jesse)
Remove hunks which didn't belong (Jesse)

v5: Don't subtract guard page since we now killed the guard page prior
to this patch. (Ben)

v6: Rebased and removed guard page stuff.
Added a chunk to the commit message
Allow adding a context to mappable region

v7: Undo v3, so we can make the drm patch last in the series

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org> (v4)
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>

squash: drm/i915: allow PPGTT to use mappable
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

The plan to to make every file descriptor have a default context. To
accommodate this, generalize out default context setup function so it
can be used at file open time.
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

We **need** to do this for exactly 1 reason, because we want to embed a
PPGTT into the context, but we don't want to special case the default
context.

To achieve that, we must be able to initialize contexts after the GTT is
setup (so we can allocate and pin the default context's BO), but before
the PPGTT and rings are initialized. This is because, currently, context
initialization requires ring usage. We don't have rings until after the
GTT is setup. If we split the enabling part of context initialization,
the part requiring the ringbuffer, we can untangle this, and then later
embed the PPGTT

Incidentally this allows us to also adhere to the original design of
context init/fini in future patches: they were only ever meant to be
called at driver load and unload.

v2: Move hw_contexts_disabled test in i915_gem_context_enable() (Chris)

v3: BUG_ON after checking for disabled contexts. Or else it blows up pre
gen6 (Ben)

v4: Forward port
Modified enable for each ring, since that patch is earlier in the series
Dropped ring arg from create_default_context so it can be used by others
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This patch adds to changes for contexts on reset:
Sets last context to default - this will prevent the context switch
happening after a reset. That switch is not possible because the
rings are hung during reset and context switch requires reset. This
behavior will need to be reworked in the future, but this is what we
want for now.

In the future, we'll also want to reset the guilty context to
uninitialized. We should wait for ARB_Robustness related code to land
for that.

This is somewhat for paranoia.  Because we really don't know what the
GPU was doing when it hung, or the state it was in (mid context write,
for example), later restoring the context is a bad idea. By setting the
flag to not initialized, the next load of that context will not restore
the state, and thus on the subsequent switch away from the context will
overwrite the old data.

NOTE: This code needs a fixup when we actually have multiple VMs. The
issue that can occur is inactive objects in a VM will need to be
destroyed before the last context unref. This can now happen via the
fake switch introduced in this patch (and it other ways in the future)
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Previously we dropped the association of a context to a ring. It is
however very important to know which ring a context ran on (we could
have reused the other member, but I was nitpicky).

This is very important when we switch address spaces, which unlike
context objects, do change per ring.

As an example, if we have:

        RCS   BCS
ctx            A
ctx      A
ctx      B
ctx            B

Without tracking the last ring B ran on, we wouldn't know to switch the
address space on BCS in the last row.

As a result, we no longer need to track which ring a context "belongs"
to, as it never really made much sense anyway.
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

If we want to use contexts in more abstract terms (specifically with
PPGTT in mind), we need to allow them to be specified for any ring.

Since the upcoming patches will bring about the use of multiple address
spaces, and each ring needs to have an address space programmed (which
we intend to do at context switch time), we can no longer only use RCS.

With multiple rings having a last context, we must now unreference these
contexts.

NOTE: This commit requires an update to intel-gpu-tools to make it not
fail.

v2: Rebased with some logical conflicts.
Squashed in the context fini refcount patch
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>