Reviewed-by: Felix Kuehling <Felix.Kuehling at amd.com>
Thanks,
Felix
On 2017-09-07 06:11 AM, Christian König wrote:
> From: Christian König <christian.koenig at amd.com>
>
> 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
>
> Signed-off-by: Christian König <christian.koenig at amd.com>
> Reviewed-by: Felix Kuehling <Felix.Kuehling at amd.com> (v1)
> ---
> drivers/gpu/drm/amd/amdgpu/amdgpu.h | 4 +-
> drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c | 78 ++++++++++++++++++++++++++++++++--
> 2 files changed, 76 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> index 0f2d903..28fae72 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> @@ -1202,11 +1202,11 @@ 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 99edb40..89743bb 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 {
> @@ -126,6 +128,53 @@ void amdgpu_mn_unlock(struct amdgpu_mn *mn)
> }
>
> /**
> + * 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_lock - take the write side lock of this mn
> + */
> +void amdgpu_mn_lock(struct amdgpu_mn *mn)
> +{
> + if (mn)
> + down_write(&mn->lock);
> +}
> +
> +/**
> + * amdgpu_mn_unlock - drop the write side lock for this mn
> + */
> +void amdgpu_mn_unlock(struct amdgpu_mn *mn)
> +{
> + if (mn)
> + up_write(&mn->lock);
> +}
> +
> +/**
> * amdgpu_mn_invalidate_node - unmap all BOs of a node
> *
> * @node: the node with the BOs to unmap
> @@ -171,7 +220,7 @@ 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 +230,7 @@ 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 +255,7 @@ 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 +266,33 @@ 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 +329,8 @@ 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)
