EHL and JSL add the 'Bypass LLC' MOCS entry, which should make it
possible for userspace to bypass the GTT caching bits set by the kernel,
as per the given object cache_level. This is troublesome since the heavy
flush we apply when first acquiring the pages is skipped if the kernel
thinks the object is coherent with the GPU. As a result it might be
possible to bypass the cache and read the contents of the page directly,
which could be stale data. If it's just a case of userspace shooting
themselves in the foot then so be it, but since i915 takes the stance of
always zeroing memory before handing it to userspace, we need to prevent
this.
v2: this time actually set cache_dirty in put_pages()
v3: move to get_pages() which looks simpler
BSpec: 34007
References: 046091758b ("Revert "drm/i915/ehl: Update MOCS table for EHL"")
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Tejas Upadhyay <tejaskumarx.surendrakumar.upadhyay@intel.com>
Cc: Francisco Jerez <francisco.jerez.plata@intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: Jon Bloomfield <jon.bloomfield@intel.com>
Cc: Chris Wilson <chris.p.wilson@intel.com>
Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210723105045.400841-2-matthew.auld@intel.com
For some specialised objects we might need something larger than the
regions min_page_size due to some hw restriction, and slightly more
hairy is needing something smaller with the guarantee that such objects
will never be inserted into any GTT, which is the case for the paging
structures.
This also fixes how we setup the BO page_alignment, if we later migrate
the object somewhere else. For example if the placements are {SMEM,
LMEM}, then we might get this wrong. Pushing the min_page_size behaviour
into the manager should fix this.
v2(Thomas): push the default page size behaviour into buddy_man, and let
the user override it with the page-alignment, which looks cleaner
v3: rebase on ttm sys changes
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210625103824.558481-1-matthew.auld@intel.com
For discrete, use TTM for both cached and WC system memory. That means
we currently rely on the TTM memory accounting / shrinker. For cached
system memory we should consider remaining shmem-backed, which can be
implemented from our ttm_tt_populate callback. We can then also reuse our
own very elaborate shrinker for that memory.
If an object is evicted to a gem allowable region, we will now consider
the object migrated, and we flip the gem region and move the object to a
different region list. Since we are now changing gem regions, we can't
any longer rely on the CONTIGUOUS flag being set based on the region
min page size, so remove that flag update. If we want to reintroduce it,
we need to put it in the mutable flags.
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210624084240.270219-4-thomas.hellstrom@linux.intel.com
The obj->stolen is currently used to identify an object allocated from
stolen memory. This dates back to when there were just 1.5 types of
objects, an object backed by shmemfs and an object backed by shmemfs
with a contiguous physical address. Now that we have several different
types of objects, we no longer want to treat stolen objects as a special
case.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210119214336.1463-3-chris@chris-wilson.co.uk
Since reservation_object_fini() does an immediate free, rather than
kfree_rcu as normal, we have to delay the release until after the RCU
grace period has elapsed (i.e. from the rcu cleanup callback) so that we
can rely on the RCU protected access to the fences while the object is a
zombie.
i915_gem_busy_ioctl relies on having an RCU barrier to protect the
reservation in order to avoid having to take a reference and strong
memory barriers.
v2: Order is important; only release after putting the pages!
Fixes: c03467ba40 ("drm/i915/gem: Free pages before rcu-freeing the object")
Testcase: igt/gem_busy/close-race
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Matthew Auld <matthew.auld@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190703180601.10950-1-chris@chris-wilson.co.uk
Currently the purgeable objects, I915_MADV_DONTNEED, are mixed in the
normal bound/unbound lists. Every shrinker pass starts with an attempt
to purge from this set of unneeded objects, which entails us doing a
walk over both lists looking for any candidates. If there are none, and
since we are shrinking we can reasonably assume that the lists are
full!, this becomes a very slow futile walk.
If we separate out the purgeable objects into own list, this search then
becomes its own phase that is preferentially handled during shrinking.
Instead the cost becomes that we then need to filter the purgeable list
if we want to distinguish between bound and unbound objects.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Matthew Auld <matthew.william.auld@gmail.com>
Reviewed-by: Matthew Auld <matthew.william.auld@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190530203500.26272-1-chris@chris-wilson.co.uk
