IB/mlx5: Add mlx5_ib_update_mtt to update page tables after creation
authorHaggai Eran <haggaie@mellanox.com>
Thu, 11 Dec 2014 15:04:22 +0000 (17:04 +0200)
committerRoland Dreier <roland@purestorage.com>
Tue, 16 Dec 2014 02:19:02 +0000 (18:19 -0800)
The new function allows updating the page tables of a memory region
after it was created. This can be used to handle page faults and page
invalidations.

Since mlx5_ib_update_mtt will need to work from within page invalidation,
so it must not block on memory allocation. It employs an atomic memory
allocation mechanism that is used as a fallback when kmalloc(GFP_ATOMIC) fails.

In order to reuse code from mlx5_ib_populate_pas, the patch splits
this function and add the needed parameters.

Signed-off-by: Haggai Eran <haggaie@mellanox.com>
Signed-off-by: Shachar Raindel <raindel@mellanox.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>
drivers/infiniband/hw/mlx5/mem.c
drivers/infiniband/hw/mlx5/mlx5_ib.h
drivers/infiniband/hw/mlx5/mr.c
include/linux/mlx5/device.h

index 5f7b301..b56e4c5 100644 (file)
@@ -140,12 +140,16 @@ static u64 umem_dma_to_mtt(dma_addr_t umem_dma)
  * dev - mlx5_ib device
  * umem - umem to use to fill the pages
  * page_shift - determines the page size used in the resulting array
+ * offset - offset into the umem to start from,
+ *          only implemented for ODP umems
+ * num_pages - total number of pages to fill
  * pas - bus addresses array to fill
  * access_flags - access flags to set on all present pages.
                  use enum mlx5_ib_mtt_access_flags for this.
  */
-void mlx5_ib_populate_pas(struct mlx5_ib_dev *dev, struct ib_umem *umem,
-                         int page_shift, __be64 *pas, int access_flags)
+void __mlx5_ib_populate_pas(struct mlx5_ib_dev *dev, struct ib_umem *umem,
+                           int page_shift, size_t offset, size_t num_pages,
+                           __be64 *pas, int access_flags)
 {
        unsigned long umem_page_shift = ilog2(umem->page_size);
        int shift = page_shift - umem_page_shift;
@@ -160,13 +164,11 @@ void mlx5_ib_populate_pas(struct mlx5_ib_dev *dev, struct ib_umem *umem,
        const bool odp = umem->odp_data != NULL;
 
        if (odp) {
-               int num_pages = ib_umem_num_pages(umem);
-
                WARN_ON(shift != 0);
                WARN_ON(access_flags != (MLX5_IB_MTT_READ | MLX5_IB_MTT_WRITE));
 
                for (i = 0; i < num_pages; ++i) {
-                       dma_addr_t pa = umem->odp_data->dma_list[i];
+                       dma_addr_t pa = umem->odp_data->dma_list[offset + i];
 
                        pas[i] = cpu_to_be64(umem_dma_to_mtt(pa));
                }
@@ -194,6 +196,13 @@ void mlx5_ib_populate_pas(struct mlx5_ib_dev *dev, struct ib_umem *umem,
        }
 }
 
+void mlx5_ib_populate_pas(struct mlx5_ib_dev *dev, struct ib_umem *umem,
+                         int page_shift, __be64 *pas, int access_flags)
+{
+       return __mlx5_ib_populate_pas(dev, umem, page_shift, 0,
+                                     ib_umem_num_pages(umem), pas,
+                                     access_flags);
+}
 int mlx5_ib_get_buf_offset(u64 addr, int page_shift, u32 *offset)
 {
        u64 page_size;
index 83c1690..6856e27 100644 (file)
@@ -527,6 +527,8 @@ struct ib_mr *mlx5_ib_get_dma_mr(struct ib_pd *pd, int acc);
 struct ib_mr *mlx5_ib_reg_user_mr(struct ib_pd *pd, u64 start, u64 length,
                                  u64 virt_addr, int access_flags,
                                  struct ib_udata *udata);
+int mlx5_ib_update_mtt(struct mlx5_ib_mr *mr, u64 start_page_index,
+                      int npages, int zap);
 int mlx5_ib_dereg_mr(struct ib_mr *ibmr);
 int mlx5_ib_destroy_mr(struct ib_mr *ibmr);
 struct ib_mr *mlx5_ib_create_mr(struct ib_pd *pd,
@@ -558,6 +560,9 @@ int mlx5_ib_init_fmr(struct mlx5_ib_dev *dev);
 void mlx5_ib_cleanup_fmr(struct mlx5_ib_dev *dev);
 void mlx5_ib_cont_pages(struct ib_umem *umem, u64 addr, int *count, int *shift,
                        int *ncont, int *order);
+void __mlx5_ib_populate_pas(struct mlx5_ib_dev *dev, struct ib_umem *umem,
+                           int page_shift, size_t offset, size_t num_pages,
+                           __be64 *pas, int access_flags);
 void mlx5_ib_populate_pas(struct mlx5_ib_dev *dev, struct ib_umem *umem,
                          int page_shift, __be64 *pas, int access_flags);
 void mlx5_ib_copy_pas(u64 *old, u64 *new, int step, int num);
index 49fc3ca..38b0626 100644 (file)
@@ -44,9 +44,13 @@ enum {
        MAX_PENDING_REG_MR = 8,
 };
 
-enum {
-       MLX5_UMR_ALIGN  = 2048
-};
+#define MLX5_UMR_ALIGN 2048
+#ifdef CONFIG_INFINIBAND_ON_DEMAND_PAGING
+static __be64 mlx5_ib_update_mtt_emergency_buffer[
+               MLX5_UMR_MTT_MIN_CHUNK_SIZE/sizeof(__be64)]
+       __aligned(MLX5_UMR_ALIGN);
+static DEFINE_MUTEX(mlx5_ib_update_mtt_emergency_buffer_mutex);
+#endif
 
 static int order2idx(struct mlx5_ib_dev *dev, int order)
 {
@@ -822,6 +826,128 @@ free_mr:
        return mr;
 }
 
+#ifdef CONFIG_INFINIBAND_ON_DEMAND_PAGING
+int mlx5_ib_update_mtt(struct mlx5_ib_mr *mr, u64 start_page_index, int npages,
+                      int zap)
+{
+       struct mlx5_ib_dev *dev = mr->dev;
+       struct device *ddev = dev->ib_dev.dma_device;
+       struct umr_common *umrc = &dev->umrc;
+       struct mlx5_ib_umr_context umr_context;
+       struct ib_umem *umem = mr->umem;
+       int size;
+       __be64 *pas;
+       dma_addr_t dma;
+       struct ib_send_wr wr, *bad;
+       struct mlx5_umr_wr *umrwr = (struct mlx5_umr_wr *)&wr.wr.fast_reg;
+       struct ib_sge sg;
+       int err = 0;
+       const int page_index_alignment = MLX5_UMR_MTT_ALIGNMENT / sizeof(u64);
+       const int page_index_mask = page_index_alignment - 1;
+       size_t pages_mapped = 0;
+       size_t pages_to_map = 0;
+       size_t pages_iter = 0;
+       int use_emergency_buf = 0;
+
+       /* UMR copies MTTs in units of MLX5_UMR_MTT_ALIGNMENT bytes,
+        * so we need to align the offset and length accordingly */
+       if (start_page_index & page_index_mask) {
+               npages += start_page_index & page_index_mask;
+               start_page_index &= ~page_index_mask;
+       }
+
+       pages_to_map = ALIGN(npages, page_index_alignment);
+
+       if (start_page_index + pages_to_map > MLX5_MAX_UMR_PAGES)
+               return -EINVAL;
+
+       size = sizeof(u64) * pages_to_map;
+       size = min_t(int, PAGE_SIZE, size);
+       /* We allocate with GFP_ATOMIC to avoid recursion into page-reclaim
+        * code, when we are called from an invalidation. The pas buffer must
+        * be 2k-aligned for Connect-IB. */
+       pas = (__be64 *)get_zeroed_page(GFP_ATOMIC);
+       if (!pas) {
+               mlx5_ib_warn(dev, "unable to allocate memory during MTT update, falling back to slower chunked mechanism.\n");
+               pas = mlx5_ib_update_mtt_emergency_buffer;
+               size = MLX5_UMR_MTT_MIN_CHUNK_SIZE;
+               use_emergency_buf = 1;
+               mutex_lock(&mlx5_ib_update_mtt_emergency_buffer_mutex);
+               memset(pas, 0, size);
+       }
+       pages_iter = size / sizeof(u64);
+       dma = dma_map_single(ddev, pas, size, DMA_TO_DEVICE);
+       if (dma_mapping_error(ddev, dma)) {
+               mlx5_ib_err(dev, "unable to map DMA during MTT update.\n");
+               err = -ENOMEM;
+               goto free_pas;
+       }
+
+       for (pages_mapped = 0;
+            pages_mapped < pages_to_map && !err;
+            pages_mapped += pages_iter, start_page_index += pages_iter) {
+               dma_sync_single_for_cpu(ddev, dma, size, DMA_TO_DEVICE);
+
+               npages = min_t(size_t,
+                              pages_iter,
+                              ib_umem_num_pages(umem) - start_page_index);
+
+               if (!zap) {
+                       __mlx5_ib_populate_pas(dev, umem, PAGE_SHIFT,
+                                              start_page_index, npages, pas,
+                                              MLX5_IB_MTT_PRESENT);
+                       /* Clear padding after the pages brought from the
+                        * umem. */
+                       memset(pas + npages, 0, size - npages * sizeof(u64));
+               }
+
+               dma_sync_single_for_device(ddev, dma, size, DMA_TO_DEVICE);
+
+               memset(&wr, 0, sizeof(wr));
+               wr.wr_id = (u64)(unsigned long)&umr_context;
+
+               sg.addr = dma;
+               sg.length = ALIGN(npages * sizeof(u64),
+                               MLX5_UMR_MTT_ALIGNMENT);
+               sg.lkey = dev->umrc.mr->lkey;
+
+               wr.send_flags = MLX5_IB_SEND_UMR_FAIL_IF_FREE |
+                               MLX5_IB_SEND_UMR_UPDATE_MTT;
+               wr.sg_list = &sg;
+               wr.num_sge = 1;
+               wr.opcode = MLX5_IB_WR_UMR;
+               umrwr->npages = sg.length / sizeof(u64);
+               umrwr->page_shift = PAGE_SHIFT;
+               umrwr->mkey = mr->mmr.key;
+               umrwr->target.offset = start_page_index;
+
+               mlx5_ib_init_umr_context(&umr_context);
+               down(&umrc->sem);
+               err = ib_post_send(umrc->qp, &wr, &bad);
+               if (err) {
+                       mlx5_ib_err(dev, "UMR post send failed, err %d\n", err);
+               } else {
+                       wait_for_completion(&umr_context.done);
+                       if (umr_context.status != IB_WC_SUCCESS) {
+                               mlx5_ib_err(dev, "UMR completion failed, code %d\n",
+                                           umr_context.status);
+                               err = -EFAULT;
+                       }
+               }
+               up(&umrc->sem);
+       }
+       dma_unmap_single(ddev, dma, size, DMA_TO_DEVICE);
+
+free_pas:
+       if (!use_emergency_buf)
+               free_page((unsigned long)pas);
+       else
+               mutex_unlock(&mlx5_ib_update_mtt_emergency_buffer_mutex);
+
+       return err;
+}
+#endif
+
 static struct mlx5_ib_mr *reg_create(struct ib_pd *pd, u64 virt_addr,
                                     u64 length, struct ib_umem *umem,
                                     int npages, int page_shift,
index 64512a7..4e5bd81 100644 (file)
@@ -200,6 +200,7 @@ enum {
 
 #define MLX5_UMR_MTT_ALIGNMENT 0x40
 #define MLX5_UMR_MTT_MASK      (MLX5_UMR_MTT_ALIGNMENT - 1)
+#define MLX5_UMR_MTT_MIN_CHUNK_SIZE MLX5_UMR_MTT_ALIGNMENT
 
 enum mlx5_event {
        MLX5_EVENT_TYPE_COMP               = 0x0,