| Message ID | 20230803165238.8798-2-dakr@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Nouveau VM_BIND UAPI & DRM GPUVA Manager (merged) | expand |
On Thu, 3 Aug 2023 18:52:20 +0200 Danilo Krummrich <dakr@redhat.com> wrote: > When no custom lock is set to protect a GEMs GPUVA list, lockdep checks > should fall back to the GEM objects dma-resv lock. With the current > implementation we're setting the lock_dep_map of the GEM objects 'resv' > pointer (in case no custom lock_dep_map is set yet) on > drm_gem_private_object_init(). > > However, the GEM objects 'resv' pointer might still change after > drm_gem_private_object_init() is called, e.g. through > ttm_bo_init_reserved(). This can result in the wrong lock being tracked. > > To fix this, call dma_resv_held() directly from > drm_gem_gpuva_assert_lock_held() and fall back to the GEMs lock_dep_map > pointer only if an actual custom lock is set. > > Fixes: e6303f323b1a ("drm: manager to keep track of GPUs VA mappings") > Signed-off-by: Danilo Krummrich <dakr@redhat.com> Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com> but I'm wondering if it wouldn't be a good thing to add a drm_gem_set_resv() helper, so the core can control drm_gem_object::resv re-assignments (block them if it's happening after the GEM has been exposed to the outside world or update auxiliary data if it's happening before that). > --- > include/drm/drm_gem.h | 15 +++++++++------ > 1 file changed, 9 insertions(+), 6 deletions(-) > > diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h > index c0b13c43b459..bc9f6aa2f3fe 100644 > --- a/include/drm/drm_gem.h > +++ b/include/drm/drm_gem.h > @@ -551,15 +551,17 @@ int drm_gem_evict(struct drm_gem_object *obj); > * @lock: the lock used to protect the gpuva list. The locking primitive > * must contain a dep_map field. > * > - * Call this if you're not proctecting access to the gpuva list > - * with the dma-resv lock, otherwise, drm_gem_gpuva_init() takes care > - * of initializing lock_dep_map for you. > + * Call this if you're not proctecting access to the gpuva list with the > + * dma-resv lock, but with a custom lock. > */ > #define drm_gem_gpuva_set_lock(obj, lock) \ > - if (!(obj)->gpuva.lock_dep_map) \ > + if (!WARN((obj)->gpuva.lock_dep_map, \ > + "GEM GPUVA lock should be set only once.")) \ > (obj)->gpuva.lock_dep_map = &(lock)->dep_map > #define drm_gem_gpuva_assert_lock_held(obj) \ > - lockdep_assert(lock_is_held((obj)->gpuva.lock_dep_map)) > + lockdep_assert((obj)->gpuva.lock_dep_map ? \ > + lock_is_held((obj)->gpuva.lock_dep_map) : \ > + dma_resv_held((obj)->resv)) > #else > #define drm_gem_gpuva_set_lock(obj, lock) do {} while (0) > #define drm_gem_gpuva_assert_lock_held(obj) do {} while (0) > @@ -573,11 +575,12 @@ int drm_gem_evict(struct drm_gem_object *obj); > * > * Calling this function is only necessary for drivers intending to support the > * &drm_driver_feature DRIVER_GEM_GPUVA. > + * > + * See also drm_gem_gpuva_set_lock(). > */ > static inline void drm_gem_gpuva_init(struct drm_gem_object *obj) > { > INIT_LIST_HEAD(&obj->gpuva.list); > - drm_gem_gpuva_set_lock(obj, &obj->resv->lock.base); > } > > /**
On 8/8/23 09:21, Boris Brezillon wrote: > On Thu, 3 Aug 2023 18:52:20 +0200 > Danilo Krummrich <dakr@redhat.com> wrote: > >> When no custom lock is set to protect a GEMs GPUVA list, lockdep checks >> should fall back to the GEM objects dma-resv lock. With the current >> implementation we're setting the lock_dep_map of the GEM objects 'resv' >> pointer (in case no custom lock_dep_map is set yet) on >> drm_gem_private_object_init(). >> >> However, the GEM objects 'resv' pointer might still change after >> drm_gem_private_object_init() is called, e.g. through >> ttm_bo_init_reserved(). This can result in the wrong lock being tracked. >> >> To fix this, call dma_resv_held() directly from >> drm_gem_gpuva_assert_lock_held() and fall back to the GEMs lock_dep_map >> pointer only if an actual custom lock is set. >> >> Fixes: e6303f323b1a ("drm: manager to keep track of GPUs VA mappings") >> Signed-off-by: Danilo Krummrich <dakr@redhat.com> > > Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com> > > but I'm wondering if it wouldn't be a good thing to add a > drm_gem_set_resv() helper, so the core can control drm_gem_object::resv > re-assignments (block them if it's happening after the GEM has been > exposed to the outside world or update auxiliary data if it's happening > before that). I agree, this might be a good idea. There are quite a few places where drm_gem_object::resv is set from external code. > >> --- >> include/drm/drm_gem.h | 15 +++++++++------ >> 1 file changed, 9 insertions(+), 6 deletions(-) >> >> diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h >> index c0b13c43b459..bc9f6aa2f3fe 100644 >> --- a/include/drm/drm_gem.h >> +++ b/include/drm/drm_gem.h >> @@ -551,15 +551,17 @@ int drm_gem_evict(struct drm_gem_object *obj); >> * @lock: the lock used to protect the gpuva list. The locking primitive >> * must contain a dep_map field. >> * >> - * Call this if you're not proctecting access to the gpuva list >> - * with the dma-resv lock, otherwise, drm_gem_gpuva_init() takes care >> - * of initializing lock_dep_map for you. >> + * Call this if you're not proctecting access to the gpuva list with the >> + * dma-resv lock, but with a custom lock. >> */ >> #define drm_gem_gpuva_set_lock(obj, lock) \ >> - if (!(obj)->gpuva.lock_dep_map) \ >> + if (!WARN((obj)->gpuva.lock_dep_map, \ >> + "GEM GPUVA lock should be set only once.")) \ >> (obj)->gpuva.lock_dep_map = &(lock)->dep_map >> #define drm_gem_gpuva_assert_lock_held(obj) \ >> - lockdep_assert(lock_is_held((obj)->gpuva.lock_dep_map)) >> + lockdep_assert((obj)->gpuva.lock_dep_map ? \ >> + lock_is_held((obj)->gpuva.lock_dep_map) : \ >> + dma_resv_held((obj)->resv)) >> #else >> #define drm_gem_gpuva_set_lock(obj, lock) do {} while (0) >> #define drm_gem_gpuva_assert_lock_held(obj) do {} while (0) >> @@ -573,11 +575,12 @@ int drm_gem_evict(struct drm_gem_object *obj); >> * >> * Calling this function is only necessary for drivers intending to support the >> * &drm_driver_feature DRIVER_GEM_GPUVA. >> + * >> + * See also drm_gem_gpuva_set_lock(). >> */ >> static inline void drm_gem_gpuva_init(struct drm_gem_object *obj) >> { >> INIT_LIST_HEAD(&obj->gpuva.list); >> - drm_gem_gpuva_set_lock(obj, &obj->resv->lock.base); >> } >> >> /** >
diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h index c0b13c43b459..bc9f6aa2f3fe 100644 --- a/include/drm/drm_gem.h +++ b/include/drm/drm_gem.h @@ -551,15 +551,17 @@ int drm_gem_evict(struct drm_gem_object *obj); * @lock: the lock used to protect the gpuva list. The locking primitive * must contain a dep_map field. * - * Call this if you're not proctecting access to the gpuva list - * with the dma-resv lock, otherwise, drm_gem_gpuva_init() takes care - * of initializing lock_dep_map for you. + * Call this if you're not proctecting access to the gpuva list with the + * dma-resv lock, but with a custom lock. */ #define drm_gem_gpuva_set_lock(obj, lock) \ - if (!(obj)->gpuva.lock_dep_map) \ + if (!WARN((obj)->gpuva.lock_dep_map, \ + "GEM GPUVA lock should be set only once.")) \ (obj)->gpuva.lock_dep_map = &(lock)->dep_map #define drm_gem_gpuva_assert_lock_held(obj) \ - lockdep_assert(lock_is_held((obj)->gpuva.lock_dep_map)) + lockdep_assert((obj)->gpuva.lock_dep_map ? \ + lock_is_held((obj)->gpuva.lock_dep_map) : \ + dma_resv_held((obj)->resv)) #else #define drm_gem_gpuva_set_lock(obj, lock) do {} while (0) #define drm_gem_gpuva_assert_lock_held(obj) do {} while (0) @@ -573,11 +575,12 @@ int drm_gem_evict(struct drm_gem_object *obj); * * Calling this function is only necessary for drivers intending to support the * &drm_driver_feature DRIVER_GEM_GPUVA. + * + * See also drm_gem_gpuva_set_lock(). */ static inline void drm_gem_gpuva_init(struct drm_gem_object *obj) { INIT_LIST_HEAD(&obj->gpuva.list); - drm_gem_gpuva_set_lock(obj, &obj->resv->lock.base); } /**
When no custom lock is set to protect a GEMs GPUVA list, lockdep checks should fall back to the GEM objects dma-resv lock. With the current implementation we're setting the lock_dep_map of the GEM objects 'resv' pointer (in case no custom lock_dep_map is set yet) on drm_gem_private_object_init(). However, the GEM objects 'resv' pointer might still change after drm_gem_private_object_init() is called, e.g. through ttm_bo_init_reserved(). This can result in the wrong lock being tracked. To fix this, call dma_resv_held() directly from drm_gem_gpuva_assert_lock_held() and fall back to the GEMs lock_dep_map pointer only if an actual custom lock is set. Fixes: e6303f323b1a ("drm: manager to keep track of GPUs VA mappings") Signed-off-by: Danilo Krummrich <dakr@redhat.com> --- include/drm/drm_gem.h | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-)