From 1ed3d2567c800eca053ef86fdd3fc27b72d0192e Mon Sep 17 00:00:00 2001 From: =?utf8?q?Christian=20K=C3=B6nig?= Date: Tue, 5 Sep 2017 17:30:46 +0200 Subject: [PATCH] drm/amdgpu: keep the MMU lock until the update ends v4 MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit This is quite controversial because it adds another lock which is held during page table updates, but I don't see much other option. v2: allow multiple updates to be in flight at the same time v3: simplify the patch, take the read side only once v4: correctly fix rebase conflict Signed-off-by: Christian König Reviewed-by: Felix Kuehling Signed-off-by: Alex Deucher --- drivers/gpu/drm/amd/amdgpu/amdgpu.h | 4 +- drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c | 59 ++++++++++++++++++++++++-- 2 files changed, 57 insertions(+), 6 deletions(-) diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h index 5ee6cea8caaf..0758d9176ea1 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h @@ -1204,11 +1204,11 @@ void amdgpu_test_moves(struct amdgpu_device *adev); * MMU Notifier */ #if defined(CONFIG_MMU_NOTIFIER) +void amdgpu_mn_lock(struct amdgpu_mn *mn); +void amdgpu_mn_unlock(struct amdgpu_mn *mn); struct amdgpu_mn *amdgpu_mn_get(struct amdgpu_device *adev); int amdgpu_mn_register(struct amdgpu_bo *bo, unsigned long addr); void amdgpu_mn_unregister(struct amdgpu_bo *bo); -void amdgpu_mn_lock(struct amdgpu_mn *mn); -void amdgpu_mn_unlock(struct amdgpu_mn *mn); #else static inline void amdgpu_mn_lock(struct amdgpu_mn *mn) {} static inline void amdgpu_mn_unlock(struct amdgpu_mn *mn) {} diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c index 99edb40b5f99..521a51b37f5d 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c @@ -52,6 +52,8 @@ struct amdgpu_mn { /* objects protected by lock */ struct rw_semaphore lock; struct rb_root objects; + struct mutex read_lock; + atomic_t recursion; }; struct amdgpu_mn_node { @@ -125,6 +127,34 @@ void amdgpu_mn_unlock(struct amdgpu_mn *mn) up_write(&mn->lock); } +/** + * amdgpu_mn_read_lock - take the rmn read lock + * + * @rmn: our notifier + * + * Take the rmn read side lock. + */ +static void amdgpu_mn_read_lock(struct amdgpu_mn *rmn) +{ + mutex_lock(&rmn->read_lock); + if (atomic_inc_return(&rmn->recursion) == 1) + down_read_non_owner(&rmn->lock); + mutex_unlock(&rmn->read_lock); +} + +/** + * amdgpu_mn_read_unlock - drop the rmn read lock + * + * @rmn: our notifier + * + * Drop the rmn read side lock. + */ +static void amdgpu_mn_read_unlock(struct amdgpu_mn *rmn) +{ + if (atomic_dec_return(&rmn->recursion) == 0) + up_read_non_owner(&rmn->lock); +} + /** * amdgpu_mn_invalidate_node - unmap all BOs of a node * @@ -171,7 +201,7 @@ static void amdgpu_mn_invalidate_page(struct mmu_notifier *mn, struct amdgpu_mn *rmn = container_of(mn, struct amdgpu_mn, mn); struct interval_tree_node *it; - down_read(&rmn->lock); + amdgpu_mn_read_lock(rmn); it = interval_tree_iter_first(&rmn->objects, address, address); if (it) { @@ -181,7 +211,7 @@ static void amdgpu_mn_invalidate_page(struct mmu_notifier *mn, amdgpu_mn_invalidate_node(node, address, address); } - up_read(&rmn->lock); + amdgpu_mn_read_unlock(rmn); } /** @@ -206,7 +236,7 @@ static void amdgpu_mn_invalidate_range_start(struct mmu_notifier *mn, /* notification is exclusive, but interval is inclusive */ end -= 1; - down_read(&rmn->lock); + amdgpu_mn_read_lock(rmn); it = interval_tree_iter_first(&rmn->objects, start, end); while (it) { @@ -217,14 +247,33 @@ static void amdgpu_mn_invalidate_range_start(struct mmu_notifier *mn, amdgpu_mn_invalidate_node(node, start, end); } +} + +/** + * amdgpu_mn_invalidate_range_end - callback to notify about mm change + * + * @mn: our notifier + * @mn: the mm this callback is about + * @start: start of updated range + * @end: end of updated range + * + * Release the lock again to allow new command submissions. + */ +static void amdgpu_mn_invalidate_range_end(struct mmu_notifier *mn, + struct mm_struct *mm, + unsigned long start, + unsigned long end) +{ + struct amdgpu_mn *rmn = container_of(mn, struct amdgpu_mn, mn); - up_read(&rmn->lock); + amdgpu_mn_read_unlock(rmn); } static const struct mmu_notifier_ops amdgpu_mn_ops = { .release = amdgpu_mn_release, .invalidate_page = amdgpu_mn_invalidate_page, .invalidate_range_start = amdgpu_mn_invalidate_range_start, + .invalidate_range_end = amdgpu_mn_invalidate_range_end, }; /** @@ -261,6 +310,8 @@ struct amdgpu_mn *amdgpu_mn_get(struct amdgpu_device *adev) rmn->mn.ops = &amdgpu_mn_ops; init_rwsem(&rmn->lock); rmn->objects = RB_ROOT; + mutex_init(&rmn->read_lock); + atomic_set(&rmn->recursion, 0); r = __mmu_notifier_register(&rmn->mn, mm); if (r) -- 2.39.2