[PATCH v2 16/17] IB/mlx5: Add support for RDMA read/write responder page faults

Haggai Eran
2014-11-11T16:36:22Z

Signed-off-by: Shachar Raindel <raindel-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
Signed-off-by: Haggai Eran <haggaie-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
---
drivers/infiniband/hw/mlx5/odp.c | 79 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 79 insertions(+)

diff --git a/drivers/infiniband/hw/mlx5/odp.c b/drivers/infiniband/hw/mlx5/odp.c
index bd1dbe5ebc15..936a6cd4ecc7 100644
--- a/drivers/infiniband/hw/mlx5/odp.c
+++ b/drivers/infiniband/hw/mlx5/odp.c
@@ -35,6 +35,8 @@

#include "mlx5_ib.h"

+#define MAX_PREFETCH_LEN (4*1024*1024U)
+
struct workqueue_struct *mlx5_ib_page_fault_wq;

#define COPY_ODP_BIT_MLX_TO_IB(reg, ib_caps, field_name, bit_name) do { \
@@ -490,6 +492,80 @@ resolve_page_fault:
free_page((unsigned long)buffer);
}

+static int pages_in_range(u64 address, u32 length)
+{
+ return (ALIGN(address + length, PAGE_SIZE) -
+ (address & PAGE_MASK)) >> PAGE_SHIFT;
+}
+
+static void mlx5_ib_mr_rdma_pfault_handler(struct mlx5_ib_qp *qp,
+ struct mlx5_ib_pfault *pfault)
+{
+ struct mlx5_pagefault *mpfault = &pfault->mpfault;
+ u64 address;
+ u32 length;
+ u32 prefetch_len = mpfault->bytes_committed;
+ int prefetch_activated = 0;
+ u32 rkey = mpfault->rdma.r_key;
+ int ret;
+
+ /* The RDMA responder handler handles the page fault in two parts.
+ * First it brings the necessary pages for the current packet
+ * (and uses the pfault context), and then (after resuming the QP)
+ * prefetches more pages. The second operation cannot use the pfault
+ * context and therefore uses the dummy_pfault context allocated on
+ * the stack */
+ struct mlx5_ib_pfault dummy_pfault = {};
+
+ dummy_pfault.mpfault.bytes_committed = 0;
+
+ mpfault->rdma.rdma_va += mpfault->bytes_committed;
+ mpfault->rdma.rdma_op_len -= min(mpfault->bytes_committed,
+ mpfault->rdma.rdma_op_len);
+ mpfault->bytes_committed = 0;
+
+ address = mpfault->rdma.rdma_va;
+ length = mpfault->rdma.rdma_op_len;
+
+ /* For some operations, the hardware cannot tell the exact message
+ * length, and in those cases it reports zero. Use prefetch
+ * logic. */
+ if (length == 0) {
+ prefetch_activated = 1;
+ length = mpfault->rdma.packet_size;
+ prefetch_len = min(MAX_PREFETCH_LEN, prefetch_len);
+ }
+
+ ret = pagefault_single_data_segment(qp, pfault, rkey, address, length,
+ NULL);
+ if (ret == -EAGAIN) {
+ /* We're racing with an invalidation, don't prefetch */
+ prefetch_activated = 0;
+ } else if (ret < 0 || pages_in_range(address, length) > ret) {
+ mlx5_ib_page_fault_resume(qp, pfault, 1);
+ return;
+ }
+
+ mlx5_ib_page_fault_resume(qp, pfault, 0);
+
+ /* At this point, there might be a new pagefault already arriving in
+ * the eq, switch to the dummy pagefault for the rest of the
+ * processing. We're still OK with the objects being alive as the
+ * work-queue is being fenced. */
+
+ if (prefetch_activated) {
+ ret = pagefault_single_data_segment(qp, &dummy_pfault, rkey,
+ address,
+ prefetch_len,
+ NULL);
+ if (ret < 0) {
+ pr_warn("Prefetch failed (ret = %d, prefetch_activated = %d) for QPN %d, address: 0x%.16llx, length = 0x%.16x\n",
+ ret, prefetch_activated,
+ qp->ibqp.qp_num, address, prefetch_len);
+ }
+ }
+}
+
void mlx5_ib_mr_pfault_handler(struct mlx5_ib_qp *qp,
struct mlx5_ib_pfault *pfault)
{
@@ -499,6 +575,9 @@ void mlx5_ib_mr_pfault_handler(struct mlx5_ib_qp *qp,
case MLX5_PFAULT_SUBTYPE_WQE:
mlx5_ib_mr_wqe_pfault_handler(qp, pfault);
break;
+ case MLX5_PFAULT_SUBTYPE_RDMA:
+ mlx5_ib_mr_rdma_pfault_handler(qp, pfault);
+ break;
default:
pr_warn("Invalid page fault event subtype: 0x%x\n",
event_subtype);