IB/core: Enable ODP sync without faulting

Enable ODP sync without faulting, this improves performance by reducing
the number of page faults in the system.

The gain from this option is that the device page table can be aligned
with the presented pages in the CPU page table without causing page
faults.

As of that, the overhead on data path from hardware point of view to
trigger a fault which end-up by calling the driver to bring the pages
will be dropped.

Link: https://lore.kernel.org/r/20200930163828.1336747-3-leon@kernel.org
Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

diff --git a/drivers/infiniband/core/umem_odp.c b/drivers/infiniband/core/umem_odp.c
index ad3b2ec688e888d7f54d4ebec5f07dbde4e6b852..323f6cf006824e2946f79beccd828d8f38cc2faf 100644 (file)
--- a/drivers/infiniband/core/umem_odp.c
+++ b/drivers/infiniband/core/umem_odp.c
@@ -347,9 +347,10 @@ static int ib_umem_odp_map_dma_single_page(
  *        the return value.
  * @access_mask: bit mask of the requested access permissions for the given
  *               range.
+ * @fault: is faulting required for the given range
  */
 int ib_umem_odp_map_dma_and_lock(struct ib_umem_odp *umem_odp, u64 user_virt,
-                                u64 bcnt, u64 access_mask)
+                                u64 bcnt, u64 access_mask, bool fault)
                        __acquires(&umem_odp->umem_mutex)
 {
        struct task_struct *owning_process  = NULL;
@@ -385,10 +386,12 @@ int ib_umem_odp_map_dma_and_lock(struct ib_umem_odp *umem_odp, u64 user_virt,
        range.end = ALIGN(user_virt + bcnt, 1UL << page_shift);
        pfn_start_idx = (range.start - ib_umem_start(umem_odp)) >> PAGE_SHIFT;
        num_pfns = (range.end - range.start) >> PAGE_SHIFT;
-       range.default_flags = HMM_PFN_REQ_FAULT;
+       if (fault) {
+               range.default_flags = HMM_PFN_REQ_FAULT;
 
-       if (access_mask & ODP_WRITE_ALLOWED_BIT)
-               range.default_flags |= HMM_PFN_REQ_WRITE;
+               if (access_mask & ODP_WRITE_ALLOWED_BIT)
+                       range.default_flags |= HMM_PFN_REQ_WRITE;
+       }
 
        range.hmm_pfns = &(umem_odp->pfn_list[pfn_start_idx]);
        timeout = jiffies + msecs_to_jiffies(HMM_RANGE_DEFAULT_TIMEOUT);
@@ -417,12 +420,24 @@ retry:
 
        for (pfn_index = 0; pfn_index < num_pfns;
                pfn_index += 1 << (page_shift - PAGE_SHIFT), dma_index++) {
-               /*
-                * Since we asked for hmm_range_fault() to populate pages,
-                * it shouldn't return an error entry on success.
-                */
-               WARN_ON(range.hmm_pfns[pfn_index] & HMM_PFN_ERROR);
-               WARN_ON(!(range.hmm_pfns[pfn_index] & HMM_PFN_VALID));
+
+               if (fault) {
+                       /*
+                        * Since we asked for hmm_range_fault() to populate
+                        * pages it shouldn't return an error entry on success.
+                        */
+                       WARN_ON(range.hmm_pfns[pfn_index] & HMM_PFN_ERROR);
+                       WARN_ON(!(range.hmm_pfns[pfn_index] & HMM_PFN_VALID));
+               } else {
+                       if (!(range.hmm_pfns[pfn_index] & HMM_PFN_VALID)) {
+                               WARN_ON(umem_odp->dma_list[dma_index]);
+                               continue;
+                       }
+                       access_mask = ODP_READ_ALLOWED_BIT;
+                       if (range.hmm_pfns[pfn_index] & HMM_PFN_WRITE)
+                               access_mask |= ODP_WRITE_ALLOWED_BIT;
+               }
+
                hmm_order = hmm_pfn_to_map_order(range.hmm_pfns[pfn_index]);
                /* If a hugepage was detected and ODP wasn't set for, the umem
                 * page_shift will be used, the opposite case is an error.

diff --git a/drivers/infiniband/hw/mlx5/odp.c b/drivers/infiniband/hw/mlx5/odp.c
index cca9e85b2ea49eadc7fb2a1a69b86d3f09a2400d..4743ef78afe08625c073f6cb432b803953b9723c 100644 (file)
--- a/drivers/infiniband/hw/mlx5/odp.c
+++ b/drivers/infiniband/hw/mlx5/odp.c
@@ -681,7 +681,7 @@ 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;
 
-       np = ib_umem_odp_map_dma_and_lock(odp, user_va, bcnt, access_mask);
+       np = ib_umem_odp_map_dma_and_lock(odp, user_va, bcnt, access_mask, true);
        if (np < 0)
                return np;
 

diff --git a/include/rdma/ib_umem_odp.h b/include/rdma/ib_umem_odp.h
index a53b62ac8a9d8dfda16f8f2b1d76ab0da60b4b89..0844c1d05ac619b5d3c0c58263088d0f09fbdcc1 100644 (file)
--- a/include/rdma/ib_umem_odp.h
+++ b/include/rdma/ib_umem_odp.h
@@ -94,7 +94,7 @@ ib_umem_odp_alloc_child(struct ib_umem_odp *root_umem, unsigned long addr,
 void ib_umem_odp_release(struct ib_umem_odp *umem_odp);
 
 int ib_umem_odp_map_dma_and_lock(struct ib_umem_odp *umem_odp, u64 start_offset,
-                                u64 bcnt, u64 access_mask);
+                                u64 bcnt, u64 access_mask, bool fault);
 
 void ib_umem_odp_unmap_dma_pages(struct ib_umem_odp *umem_odp, u64 start_offset,
                                 u64 bound);