RDMA/umem: Set iova in ODP flow

Fixing the ODP registration flow to set the iova correctly.
The calculation in ib_umem_num_dma_blocks() function assumes the iova of
the umem is set correctly.

When iova is not set, the calculation in ib_umem_num_dma_blocks() is
equivalent to length/page_size, which is true only when memory is aligned.
For unaligned memory, iova must be set for the ALIGN() in the
ib_umem_num_dma_blocks() to take effect and return a correct value.

mlx5_ib uses ib_umem_num_dma_blocks() to decide the mkey size to use for
the MR. Without this fix, when registering unaligned ODP MR, a wrong
size mkey might be chosen and this might cause the UMR to fail.

UMR would fail over insufficient size to update the mkey translation:
infiniband mlx5_0: dump_cqe:273:(pid 0): dump error cqe
00000000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00000010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00000030: 00 00 00 00 0f 00 78 06 25 00 00 58 00 da ac d2
infiniband mlx5_0: mlx5_ib_post_send_wait:806:(pid 20311): reg umr
failed (6)
infiniband mlx5_0: pagefault_real_mr:661:(pid 20311): Failed to update
mkey page tables

Fixes: f0093fb1a7 ("RDMA/mlx5: Move mlx5_ib_cont_pages() to the creation of the mlx5_ib_mr")
Fixes: a665aca89a ("RDMA/umem: Split ib_umem_num_pages() into ib_umem_num_dma_blocks()")
Signed-off-by: Artemy Kovalyov <artemyko@nvidia.com>
Signed-off-by: Michael Guralnik <michaelgur@nvidia.com>
Link: https://lore.kernel.org/r/3d4be7ca2155bf239dd8c00a2d25974a92c26ab8.1689757344.git.leon@kernel.org
Signed-off-by: Leon Romanovsky <leon@kernel.org>

drivers/infiniband/core/umem.c

@@ -85,6 +85,8 @@ unsigned long ib_umem_find_best_pgsz(struct ib_umem *umem,
 	dma_addr_t mask;
 	int i;
 
+	umem->iova = va = virt;
+
 	if (umem->is_odp) {
 		unsigned int page_size = BIT(to_ib_umem_odp(umem)->page_shift);
 
@@ -100,7 +102,6 @@ unsigned long ib_umem_find_best_pgsz(struct ib_umem *umem,
 	 */
 	pgsz_bitmap &= GENMASK(BITS_PER_LONG - 1, PAGE_SHIFT);
 
-	umem->iova = va = virt;
 	/* The best result is the smallest page size that results in the minimum
 	 * number of required pages. Compute the largest page size that could
 	 * work based on VA address bits that don't change.