vlib: introduce DMA infrastructure

This patch introduces DMA infrastructure into vlib. This is well known
that large amount of memory movements will drain core resource. Nowadays
more and more hardware accelerators were designed out for freeing core
from this burden. Meanwhile some restrictions still remained when
utilizing hardware accelerators, e.g. cross numa throughput will have a
significant drop compared to same node. Normally the number of hardware
accelerator instances will less than cores number, not to mention that
applications number will even beyond the number of cores. Some hardware
may support share virtual address with cores, while others are not.

Here we introduce new DMA infrastructure which can fulfill the
requirements of vpp applications like session and memif and in the
meantime dealing with hardware limitations.

Here is some design backgrounds:

  Backend is the abstract of resource which allocated from DMA device
  and can do some basic operations like configuration, DMA copy and
  result query.

  Config is the abstract of application DMA requirement. Application
  need to request an unique config index from DMA infrastructure. This
  unique config index is associated with backend resource. Two options
  cpu fallback and barrier before last can be specified in config.
  DMA transfer will be performed by CPU when backend is busy if cpu
  fallback option is enabled. DMA transfer callback will be in order
  if barrier before last option is enabled.

  We constructs all the stuffs that DMA transfer request needed into
  DMA batch. It contains the pattern of DMA descriptors and function
  pointers for submission and callback. One DMA transfer request need
  multiple times batch update and one time batch submission.

  DMA backends will assigned to config's workers threads equally. Lock
  will be used for thread-safety if same backends assigned to multiple
  threads. Backend node will check all the pending requests in worker
  thread and do callback with the pointer of DMA batch if transfer
  completed. Application can utilize cookie in DMA batch for selves
  usage.

DMA architecture:

   +----------+   +----------+           +----------+   +----------+
   | Config1  |   | Config2  |           | Config1  |   | Config2  |
   +----------+   +----------+           +----------+   +----------+
        ||             ||                     ||             ||
   +-------------------------+           +-------------------------+
   |  DMA polling thread A   |           |  DMA polling thread B   |
   +-------------------------+           +-------------------------+
               ||                                     ||
           +----------+                          +----------+
           | Backend1 |                          | Backend2 |
           +----------+                          +----------+

Type: feature

Signed-off-by: Marvin Liu <yong.liu@intel.com>
Change-Id: I1725e0c26687985aac29618c9abe4f5e0de08ebf

1 files changed, 131 insertions, 0 deletions

diff --git a/src/vlib/dma/dma.h b/src/vlib/dma/dma.h
new file mode 100644
index 00000000000..eaeba8b13b7
--- /dev/null
+++ b/src/vlib/dma/dma.h
@@ -0,0 +1,131 @@
+/* SPDX-License-Identifier: Apache-2.0
+ * Copyright (c) 2022 Cisco Systems, Inc.
+ */
+
+#ifndef included_vlib_dma_h
+#define included_vlib_dma_h
+#include <vlib/vlib.h>
+
+#define dma_log_debug(f, ...)                                                 \
+  vlib_log (VLIB_LOG_LEVEL_DEBUG, dma_log.class, "%s: " f, __func__,          \
+	    ##__VA_ARGS__)
+
+#define dma_log_info(f, ...)                                                  \
+  vlib_log (VLIB_LOG_LEVEL_INFO, dma_log.class, "%s: " f, __func__,           \
+	    ##__VA_ARGS__)
+
+struct vlib_dma_batch;
+struct vlib_dma_config_data;
+
+typedef int (vlib_dma_config_add_fn) (vlib_main_t *vm,
+				      struct vlib_dma_config_data *cfg);
+typedef void (vlib_dma_config_del_fn) (vlib_main_t *vm,
+				       struct vlib_dma_config_data *cfg);
+typedef struct vlib_dma_batch *(vlib_dma_batch_new_fn) (
+  vlib_main_t *vm, struct vlib_dma_config_data *);
+typedef int (vlib_dma_batch_submit_fn) (vlib_main_t *vm,
+					struct vlib_dma_batch *b);
+typedef void (vlib_dma_batch_callback_fn) (vlib_main_t *vm,
+					   struct vlib_dma_batch *b);
+typedef struct
+{
+  union
+  {
+    struct
+    {
+      u32 barrier_before_last : 1;
+      u32 sw_fallback : 1;
+    };
+    u32 features;
+  };
+  u16 max_transfers;
+  u32 max_transfer_size;
+  vlib_dma_batch_callback_fn *callback_fn;
+} vlib_dma_config_t;
+
+typedef struct vlib_dma_batch
+{
+  vlib_dma_batch_submit_fn *submit_fn;
+  vlib_dma_batch_callback_fn *callback_fn;
+  uword cookie;
+  u16 src_ptr_off;
+  u16 dst_ptr_off;
+  u16 size_off;
+  u16 stride;
+  u16 n_enq;
+} vlib_dma_batch_t;
+
+typedef struct
+{
+  char *name;
+  vlib_dma_config_add_fn *config_add_fn;
+  vlib_dma_config_del_fn *config_del_fn;
+  format_function_t *info_fn;
+} vlib_dma_backend_t;
+
+typedef struct vlib_dma_config_data
+{
+  vlib_dma_config_t cfg;
+  vlib_dma_batch_new_fn *batch_new_fn;
+  uword private_data;
+  u32 backend_index;
+  u32 config_index;
+} vlib_dma_config_data_t;
+
+typedef struct
+{
+  vlib_dma_backend_t *backends;
+  vlib_dma_config_data_t *configs;
+} vlib_dma_main_t;
+
+extern vlib_dma_main_t vlib_dma_main;
+
+clib_error_t *vlib_dma_register_backend (vlib_main_t *vm,
+					 vlib_dma_backend_t *b);
+
+int vlib_dma_config_add (vlib_main_t *vm, vlib_dma_config_t *b);
+void vlib_dma_config_del (vlib_main_t *vm, u32 config_index);
+u8 *vlib_dma_config_info (u8 *s, va_list *args);
+
+static_always_inline vlib_dma_batch_t *
+vlib_dma_batch_new (vlib_main_t *vm, u32 config_index)
+{
+  vlib_dma_main_t *dm = &vlib_dma_main;
+  vlib_dma_config_data_t *cd = pool_elt_at_index (dm->configs, config_index);
+
+  return cd->batch_new_fn (vm, cd);
+}
+
+static_always_inline void
+vlib_dma_batch_set_cookie (vlib_main_t *vm, vlib_dma_batch_t *batch,
+			   uword cookie)
+{
+  batch->cookie = cookie;
+}
+
+static_always_inline uword
+vlib_dma_batch_get_cookie (vlib_main_t *vm, vlib_dma_batch_t *batch)
+{
+  return batch->cookie;
+}
+
+static_always_inline void
+vlib_dma_batch_add (vlib_main_t *vm, vlib_dma_batch_t *batch, void *dst,
+		    void *src, u32 size)
+{
+  u8 *p = (u8 *) batch + batch->n_enq * batch->stride;
+
+  *((void **) (p + batch->dst_ptr_off)) = dst;
+  *((void **) (p + batch->src_ptr_off)) = src;
+  *((u32 *) (p + batch->size_off)) = size;
+
+  batch->n_enq++;
+}
+
+static_always_inline void
+vlib_dma_batch_submit (vlib_main_t *vm, vlib_dma_batch_t *batch)
+{
+  batch->submit_fn (vm, batch);
+}
+
+#endif