Merge tag 'for-linus-hmm' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma

Pull hmm updates from Jason Gunthorpe:
 "This is another round of bug fixing and cleanup. This time the focus
  is on the driver pattern to use mmu notifiers to monitor a VA range.
  This code is lifted out of many drivers and hmm_mirror directly into
  the mmu_notifier core and written using the best ideas from all the
  driver implementations.

  This removes many bugs from the drivers and has a very pleasing
  diffstat. More drivers can still be converted, but that is for another
  cycle.

   - A shared branch with RDMA reworking the RDMA ODP implementation

   - New mmu_interval_notifier API. This is focused on the use case of
     monitoring a VA and simplifies the process for drivers

   - A common seq-count locking scheme built into the
     mmu_interval_notifier API usable by drivers that call
     get_user_pages() or hmm_range_fault() with the VA range

   - Conversion of mlx5 ODP, hfi1, radeon, nouveau, AMD GPU, and Xen
     GntDev drivers to the new API. This deletes a lot of wonky driver
     code.

   - Two improvements for hmm_range_fault(), from testing done by Ralph"

* tag 'for-linus-hmm' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma:
  mm/hmm: remove hmm_range_dma_map and hmm_range_dma_unmap
  mm/hmm: make full use of walk_page_range()
  xen/gntdev: use mmu_interval_notifier_insert
  mm/hmm: remove hmm_mirror and related
  drm/amdgpu: Use mmu_interval_notifier instead of hmm_mirror
  drm/amdgpu: Use mmu_interval_insert instead of hmm_mirror
  drm/amdgpu: Call find_vma under mmap_sem
  nouveau: use mmu_interval_notifier instead of hmm_mirror
  nouveau: use mmu_notifier directly for invalidate_range_start
  drm/radeon: use mmu_interval_notifier_insert
  RDMA/hfi1: Use mmu_interval_notifier_insert for user_exp_rcv
  RDMA/odp: Use mmu_interval_notifier_insert()
  mm/hmm: define the pre-processor related parts of hmm.h even if disabled
  mm/hmm: allow hmm_range to be used with a mmu_interval_notifier or hmm_mirror
  mm/mmu_notifier: add an interval tree notifier
  mm/mmu_notifier: define the header pre-processor parts even if disabled
  mm/hmm: allow snapshot of the special zero page

3 files changed, 27 insertions, 33 deletions

diff --git a/drivers/infiniband/hw/mlx5/mlx5_ib.h b/drivers/infiniband/hw/mlx5/mlx5_ib.h
index 03af54b53bf7..5986953ec2fa 100644
--- a/drivers/infiniband/hw/mlx5/mlx5_ib.h
+++ b/drivers/infiniband/hw/mlx5/mlx5_ib.h
@@ -1258,8 +1258,6 @@ int mlx5_ib_odp_init_one(struct mlx5_ib_dev *ibdev);
 void mlx5_ib_odp_cleanup_one(struct mlx5_ib_dev *ibdev);
 int __init mlx5_ib_odp_init(void);
 void mlx5_ib_odp_cleanup(void);
-void mlx5_ib_invalidate_range(struct ib_umem_odp *umem_odp, unsigned long start,
-			      unsigned long end);
 void mlx5_odp_init_mr_cache_entry(struct mlx5_cache_ent *ent);
 void mlx5_odp_populate_klm(struct mlx5_klm *pklm, size_t offset,
 			   size_t nentries, struct mlx5_ib_mr *mr, int flags);
@@ -1289,11 +1287,10 @@ mlx5_ib_advise_mr_prefetch(struct ib_pd *pd,
 {
 	return -EOPNOTSUPP;
 }
-static inline void mlx5_ib_invalidate_range(struct ib_umem_odp *umem_odp,
-					    unsigned long start,
-					    unsigned long end){};
 #endif /* CONFIG_INFINIBAND_ON_DEMAND_PAGING */
 
+extern const struct mmu_interval_notifier_ops mlx5_mn_ops;
+
 /* Needed for rep profile */
 void __mlx5_ib_remove(struct mlx5_ib_dev *dev,
 		      const struct mlx5_ib_profile *profile,
diff --git a/drivers/infiniband/hw/mlx5/mr.c b/drivers/infiniband/hw/mlx5/mr.c
index 60d39b9ec41c..ea8bfc3e2d8d 100644
--- a/drivers/infiniband/hw/mlx5/mr.c
+++ b/drivers/infiniband/hw/mlx5/mr.c
@@ -749,7 +749,8 @@ static int mr_umem_get(struct mlx5_ib_dev *dev, struct ib_udata *udata,
 	if (access_flags & IB_ACCESS_ON_DEMAND) {
 		struct ib_umem_odp *odp;
 
-		odp = ib_umem_odp_get(udata, start, length, access_flags);
+		odp = ib_umem_odp_get(udata, start, length, access_flags,
+				      &mlx5_mn_ops);
 		if (IS_ERR(odp)) {
 			mlx5_ib_dbg(dev, "umem get failed (%ld)\n",
 				    PTR_ERR(odp));
diff --git a/drivers/infiniband/hw/mlx5/odp.c b/drivers/infiniband/hw/mlx5/odp.c
index 45ee40c2f36e..f924250f80c2 100644
--- a/drivers/infiniband/hw/mlx5/odp.c
+++ b/drivers/infiniband/hw/mlx5/odp.c
@@ -241,18 +241,27 @@ out_unlock:
 	xa_unlock(&imr->implicit_children);
 }
 
-void mlx5_ib_invalidate_range(struct ib_umem_odp *umem_odp, unsigned long start,
-			      unsigned long end)
+static bool mlx5_ib_invalidate_range(struct mmu_interval_notifier *mni,
+				     const struct mmu_notifier_range *range,
+				     unsigned long cur_seq)
 {
+	struct ib_umem_odp *umem_odp =
+		container_of(mni, struct ib_umem_odp, notifier);
 	struct mlx5_ib_mr *mr;
 	const u64 umr_block_mask = (MLX5_UMR_MTT_ALIGNMENT /
 				    sizeof(struct mlx5_mtt)) - 1;
 	u64 idx = 0, blk_start_idx = 0;
 	u64 invalidations = 0;
+	unsigned long start;
+	unsigned long end;
 	int in_block = 0;
 	u64 addr;
 
+	if (!mmu_notifier_range_blockable(range))
+		return false;
+
 	mutex_lock(&umem_odp->umem_mutex);
+	mmu_interval_set_seq(mni, cur_seq);
 	/*
 	 * If npages is zero then umem_odp->private may not be setup yet. This
 	 * does not complete until after the first page is mapped for DMA.
@@ -261,8 +270,8 @@ void mlx5_ib_invalidate_range(struct ib_umem_odp *umem_odp, unsigned long start,
 		goto out;
 	mr = umem_odp->private;
 
-	start = max_t(u64, ib_umem_start(umem_odp), start);
-	end = min_t(u64, ib_umem_end(umem_odp), end);
+	start = max_t(u64, ib_umem_start(umem_odp), range->start);
+	end = min_t(u64, ib_umem_end(umem_odp), range->end);
 
 	/*
 	 * Iteration one - zap the HW's MTTs. The notifiers_count ensures that
@@ -319,8 +328,13 @@ void mlx5_ib_invalidate_range(struct ib_umem_odp *umem_odp, unsigned long start,
 		destroy_unused_implicit_child_mr(mr);
 out:
 	mutex_unlock(&umem_odp->umem_mutex);
+	return true;
 }
 
+const struct mmu_interval_notifier_ops mlx5_mn_ops = {
+	.invalidate = mlx5_ib_invalidate_range,
+};
+
 void mlx5_ib_internal_fill_odp_caps(struct mlx5_ib_dev *dev)
 {
 	struct ib_odp_caps *caps = &dev->odp_caps;
@@ -419,7 +433,7 @@ static struct mlx5_ib_mr *implicit_get_child_mr(struct mlx5_ib_mr *imr,
 
 	odp = ib_umem_odp_alloc_child(to_ib_umem_odp(imr->umem),
 				      idx * MLX5_IMR_MTT_SIZE,
-				      MLX5_IMR_MTT_SIZE);
+				      MLX5_IMR_MTT_SIZE, &mlx5_mn_ops);
 	if (IS_ERR(odp))
 		return ERR_CAST(odp);
 
@@ -606,8 +620,9 @@ static int pagefault_real_mr(struct mlx5_ib_mr *mr, struct ib_umem_odp *odp,
 			     u64 user_va, size_t bcnt, u32 *bytes_mapped,
 			     u32 flags)
 {
-	int current_seq, page_shift, ret, np;
+	int page_shift, ret, np;
 	bool downgrade = flags & MLX5_PF_FLAGS_DOWNGRADE;
+	unsigned long current_seq;
 	u64 access_mask;
 	u64 start_idx, page_mask;
 
@@ -619,12 +634,7 @@ static int pagefault_real_mr(struct mlx5_ib_mr *mr, struct ib_umem_odp *odp,
 	if (odp->umem.writable && !downgrade)
 		access_mask |= ODP_WRITE_ALLOWED_BIT;
 
-	current_seq = READ_ONCE(odp->notifiers_seq);
-	/*
-	 * Ensure the sequence number is valid for some time before we call
-	 * gup.
-	 */
-	smp_rmb();
+	current_seq = mmu_interval_read_begin(&odp->notifier);
 
 	np = ib_umem_odp_map_dma_pages(odp, user_va, bcnt, access_mask,
 				       current_seq);
@@ -632,7 +642,7 @@ static int pagefault_real_mr(struct mlx5_ib_mr *mr, struct ib_umem_odp *odp,
 		return np;
 
 	mutex_lock(&odp->umem_mutex);
-	if (!ib_umem_mmu_notifier_retry(odp, current_seq)) {
+	if (!mmu_interval_read_retry(&odp->notifier, current_seq)) {
 		/*
 		 * No need to check whether the MTTs really belong to
 		 * this MR, since ib_umem_odp_map_dma_pages already
@@ -662,19 +672,6 @@ static int pagefault_real_mr(struct mlx5_ib_mr *mr, struct ib_umem_odp *odp,
 	return np << (page_shift - PAGE_SHIFT);
 
 out:
-	if (ret == -EAGAIN) {
-		unsigned long timeout = msecs_to_jiffies(MMU_NOTIFIER_TIMEOUT);
-
-		if (!wait_for_completion_timeout(&odp->notifier_completion,
-						 timeout)) {
-			mlx5_ib_warn(
-				mr->dev,
-				"timeout waiting for mmu notifier. seq %d against %d. notifiers_count=%d\n",
-				current_seq, odp->notifiers_seq,
-				odp->notifiers_count);
-		}
-	}
-
 	return ret;
 }
 
@@ -1622,7 +1619,6 @@ void mlx5_odp_init_mr_cache_entry(struct mlx5_cache_ent *ent)
 
 static const struct ib_device_ops mlx5_ib_dev_odp_ops = {
 	.advise_mr = mlx5_ib_advise_mr,
-	.invalidate_range = mlx5_ib_invalidate_range,
 };
 
 int mlx5_ib_odp_init_one(struct mlx5_ib_dev *dev)