User resource lookups used rcu to avoid two extra atomics. Unfortunately
the rcu paths were buggy and it was easy to make the driver crash by
submitting command buffers from two different threads. Because the
lookups never show up in performance profiles replace them with a
regular spin lock which fixes the races in accesses to those shared
resources.
Fixes kernel oops'es in IGT's vmwgfx execution_buffer stress test and
seen crashes with apps using shared resources.
Fixes: e14c02e6b6 ("drm/vmwgfx: Look up objects without taking a reference")
Signed-off-by: Zack Rusin <zackr@vmware.com>
Reviewed-by: Martin Krastev <krastevm@vmware.com>
Reviewed-by: Maaz Mombasawala <mombasawalam@vmware.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221207172907.959037-1-zack@kde.org
This is part of an effort to move from the vmwgfx_open_hash hashtable to
linux/hashtable implementation.
Refactor the ref_hash hashtable, used for fast lookup of reference objects
associated with a ttm file.
This also exposed a problem related to inconsistently using 32-bit and
64-bit keys with this hashtable. The hash function used changes depending
on the size of the type, and results are not consistent across numbers,
for example, hash_32(329) = 329, but hash_long(329) = 328. This would
cause the lookup to fail for objects already in the hashtable, since keys
of different sizes were being passed during adding and lookup. This was
not an issue before because vmwgfx_open_hash always used hash_long.
Fix this by always using 64-bit keys for this hashtable, which means that
hash_long is always used.
Signed-off-by: Maaz Mombasawala <mombasawalam@vmware.com>
Reviewed-by: Zack Rusin <zackr@vmware.com>
Signed-off-by: Zack Rusin <zackr@vmware.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221022040236.616490-11-zack@kde.org
This is initial change adding support for DRIVER_GEM to vmwgfx. vmwgfx
was written before GEM and has always used TTM. Over the years the
TTM buffers started inherting from GEM objects but vmwgfx never
implemented GEM making it quite awkward. We were directly setting
variables in GEM objects to not make DRM crash.
This change brings vmwgfx inline with other DRM drivers and allows us
to use a lot of DRM helpers which have depended on drivers with GEM
support.
Due to historical reasons vmwgfx splits the idea of a buffer and surface
which makes it a littly tricky since either one can be used in most
of our ioctl's which take user space handles. For now our BO's are
GEM objects and our surfaces are opaque objects which are backed by
GEM objects. In the future I'd like to combine those into a single
BO but we don't want to break any of our existing ioctl's so it will
take time to do it in a non-destructive way.
Signed-off-by: Zack Rusin <zackr@vmware.com>
Reviewed-by: Martin Krastev <krastevm@vmware.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211206172620.3139754-5-zack@kde.org
vmwgfx shared very elaborate memory accounting with ttm. It was moved
from ttm to vmwgfx in change
f07069da6b ("drm/ttm: move memory accounting into vmwgfx v4")
but because of complexity it was hard to maintain. Some parts of the code
weren't freeing memory correctly and some were missing accounting all
together. While those would be fairly easy to fix the fundamental reason
for memory accounting in the driver was the ability to invoke shrinker
which is part of TTM code as well (with support for unified memory
hopefully coming soon).
That meant that vmwgfx had a lot of code that was either unused or
duplicating code from TTM. Removing this code also prevents excessive
calls to global swapout which were common during memory pressure
because both vmwgfx and TTM would invoke the shrinker when memory
usage reached half of RAM.
Fixes: f07069da6b ("drm/ttm: move memory accounting into vmwgfx v4")
Signed-off-by: Zack Rusin <zackr@vmware.com>
Reviewed-by: Martin Krastev <krastevm@vmware.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211206172620.3139754-2-zack@kde.org
idr_init() uses base 0 which is an invalid identifier for this driver.
The idr_alloc for this driver uses 1 as start value for ID range. The
new function idr_init_base allows IDR to set the ID lookup from base 1.
This avoids all lookups that otherwise starts from 0 since 0 is always
unused / available.
References: commit 6ce711f275 ("idr: Make 1-based IDRs more efficient")
Signed-off-by: Deepak R Varma <mh12gx2825@gmail.com>
Signed-off-by: Zack Rusin <zackr@vmware.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201105190718.GA89863@localhost
Fixes the following W=1 kernel build warning(s):
drivers/gpu/drm/vmwgfx/ttm_object.c:60: error: Cannot parse struct or union!
drivers/gpu/drm/vmwgfx/ttm_object.c:97: warning: Function parameter or member 'mem_glob' not described in 'ttm_object_device'
drivers/gpu/drm/vmwgfx/ttm_object.c:97: warning: Function parameter or member 'ops' not described in 'ttm_object_device'
drivers/gpu/drm/vmwgfx/ttm_object.c:97: warning: Function parameter or member 'dmabuf_release' not described in 'ttm_object_device'
drivers/gpu/drm/vmwgfx/ttm_object.c:97: warning: Function parameter or member 'dma_buf_size' not described in 'ttm_object_device'
drivers/gpu/drm/vmwgfx/ttm_object.c:97: warning: Function parameter or member 'idr' not described in 'ttm_object_device'
drivers/gpu/drm/vmwgfx/ttm_object.c:128: warning: Function parameter or member 'rcu_head' not described in 'ttm_ref_object'
drivers/gpu/drm/vmwgfx/ttm_object.c:128: warning: Function parameter or member 'tfile' not described in 'ttm_ref_object'
drivers/gpu/drm/vmwgfx/ttm_object.c:582: warning: Function parameter or member 'dmabuf' not described in 'get_dma_buf_unless_doomed'
drivers/gpu/drm/vmwgfx/ttm_object.c:582: warning: Excess function parameter 'dma_buf' description in 'get_dma_buf_unless_doomed'
Cc: VMware Graphics <linux-graphics-maintainer@vmware.com>
Cc: Roland Scheidegger <sroland@vmware.com>
Cc: Zack Rusin <zackr@vmware.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: "Christian König" <christian.koenig@amd.com>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Rob Clark <rob.clark@linaro.org>
Cc: dri-devel@lists.freedesktop.org
Cc: linux-media@vger.kernel.org
Cc: linaro-mm-sig@lists.linaro.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Zack Rusin <zackr@vmware.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210115181601.3432599-10-lee.jones@linaro.org
User-space handles equal to zero are interpreted as uninitialized or
illegal by some drm systems (most notably kms). This means that a
dumb buffer or surface with a zero user-space handle can never be
used as a kms frame-buffer.
Cc: <stable@vger.kernel.org>
Fixes: c7eae62666 ("drm/vmwgfx: Make the object handles idr-generated")
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Deepak Rawat <drawat@vmware.com>
Typically when we look up objects under the rcu lock, we take a reference
to make sure the returned object pointer is valid.
Now provide a function to look up an object and instead of taking a
reference to it, keep the rcu lock held when returning the object pointer.
This means that the object pointer is valid as long as the rcu lock is
held, but the object may be doomed (its refcount may be zero). Any
persistent usage of the object pointer outside of the rcu lock requires
a reference to be taken using kref_get_unless_zero().
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Sinclair Yeh <syeh@vmware.com>
Instead of generating user-space object handles based on a, possibly
processed, hash of the kernel address of the object, use idr to generate
and lookup those handles. This might improve somewhat on security since
we loose all connections to the object's kernel address. Also idr is
designed to do just this.
As a todo-item, since user-space handles are now generated in sequence,
we can probably use a much simpler hash function to hash them.
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Sinclair Yeh <syeh@vmware.com>
Reviewed-by: Deepak Rawat <drawat@vmware.com>
No other driver is using this functionality so move it out of TTM and
into the vmwgfx driver. Update includes and remove exports.
Also annotate to remove false static analyzer lock balance warnings.
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
