vhost: support interrupt mode

vhost currently supports only polling mode. This patch is to add
interrupt mode. When the interface is configured for interrupt
mode, our input node does not get called unless there is a packet
in the vring.

If a particular CPU has one interface configured for polling mode
and another in interrupt, the input node is set to polling for
that CPU.

This diffs also includes two crashes in vlib's dispatch_node. One is
included in https://gerrit.fd.io/r/#/c/5516. The other crash is in
the ASSERT. The ASSERT can become true when the caller of
dispatch_node is in a loop. The first call converted the node
to polling. The second call thereafter will hit the ASSERT.

Change-Id: If17b6d48b20d7d8605c6a161459828637173cd32
Signed-off-by: Steven <sluong@cisco.com>

1 files changed, 62 insertions, 5 deletions

diff --git a/src/vat/api_format.c b/src/vat/api_format.c
index 37b7f93e879..3b57ac61717 100644
--- a/src/vat/api_format.c
+++ b/src/vat/api_format.c
@@ -403,6 +403,46 @@ api_unformat_sw_if_index (unformat_input_t * input, va_list * args)
 }
 #endif /* VPP_API_TEST_BUILTIN */
 
+#define VHOST_USER_POLLING_MODE   0
+#define VHOST_USER_INTERRUPT_MODE 1
+#define VHOST_USER_ADAPTIVE_MODE  2
+
+static u8 *
+api_format_vhost_user_operation_mode (u8 * s, va_list * va)
+{
+  int operation_mode = va_arg (*va, int);
+
+  switch (operation_mode)
+    {
+    case VHOST_USER_POLLING_MODE:
+      s = format (s, "%-9s", "polling");
+      break;
+    case VHOST_USER_INTERRUPT_MODE:
+      s = format (s, "%-9s", "interrupt");
+      break;
+    default:
+      s = format (s, "%-9s", "invalid");
+    }
+  return s;
+}
+
+static uword
+api_unformat_vhost_user_operation_mode (unformat_input_t * input,
+					va_list * args)
+{
+  u8 *operation_mode = va_arg (*args, u8 *);
+  uword rc = 1;
+
+  if (unformat (input, "interrupt"))
+    *operation_mode = VHOST_USER_INTERRUPT_MODE;
+  else if (unformat (input, "polling"))
+    *operation_mode = VHOST_USER_POLLING_MODE;
+  else
+    rc = 0;
+
+  return rc;
+}
+
 static uword
 unformat_policer_rate_type (unformat_input_t * input, va_list * args)
 {
@@ -11174,6 +11214,7 @@ api_create_vhost_user_if (vat_main_t * vam)
   u8 use_custom_mac = 0;
   u8 *tag = 0;
   int ret;
+  u8 operation_mode = VHOST_USER_POLLING_MODE;
 
   /* Shut up coverity */
   memset (hwaddr, 0, sizeof (hwaddr));
@@ -11192,6 +11233,10 @@ api_create_vhost_user_if (vat_main_t * vam)
 	is_server = 1;
       else if (unformat (i, "tag %s", &tag))
 	;
+      else if (unformat (i, "mode %U",
+			 api_unformat_vhost_user_operation_mode,
+			 &operation_mode))
+	;
       else
 	break;
     }
@@ -11211,6 +11256,7 @@ api_create_vhost_user_if (vat_main_t * vam)
 
   M (CREATE_VHOST_USER_IF, mp);
 
+  mp->operation_mode = operation_mode;
   mp->is_server = is_server;
   clib_memcpy (mp->sock_filename, file_name, vec_len (file_name));
   vec_free (file_name);
@@ -11242,6 +11288,7 @@ api_modify_vhost_user_if (vat_main_t * vam)
   u8 sw_if_index_set = 0;
   u32 sw_if_index = (u32) ~ 0;
   int ret;
+  u8 operation_mode = VHOST_USER_POLLING_MODE;
 
   while (unformat_check_input (i) != UNFORMAT_END_OF_INPUT)
     {
@@ -11257,6 +11304,10 @@ api_modify_vhost_user_if (vat_main_t * vam)
 	;
       else if (unformat (i, "server"))
 	is_server = 1;
+      else if (unformat (i, "mode %U",
+			 api_unformat_vhost_user_operation_mode,
+			 &operation_mode))
+	;
       else
 	break;
     }
@@ -11282,6 +11333,7 @@ api_modify_vhost_user_if (vat_main_t * vam)
 
   M (MODIFY_VHOST_USER_IF, mp);
 
+  mp->operation_mode = operation_mode;
   mp->sw_if_index = ntohl (sw_if_index);
   mp->is_server = is_server;
   clib_memcpy (mp->sock_filename, file_name, vec_len (file_name));
@@ -11337,11 +11389,12 @@ static void vl_api_sw_interface_vhost_user_details_t_handler
 {
   vat_main_t *vam = &vat_main;
 
-  print (vam->ofp, "%-25s %3" PRIu32 " %6" PRIu32 " %8x %6d %7d %s",
+  print (vam->ofp, "%-25s %3" PRIu32 " %6" PRIu32 " %8x %6d %7d %U %s",
 	 (char *) mp->interface_name,
 	 ntohl (mp->sw_if_index), ntohl (mp->virtio_net_hdr_sz),
 	 clib_net_to_host_u64 (mp->features), mp->is_server,
-	 ntohl (mp->num_regions), (char *) mp->sock_filename);
+	 ntohl (mp->num_regions), api_format_vhost_user_operation_mode,
+	 mp->operation_mode, (char *) mp->sock_filename);
   print (vam->ofp, "    Status: '%s'", strerror (ntohl (mp->sock_errno)));
 }
 
@@ -11370,6 +11423,7 @@ static void vl_api_sw_interface_vhost_user_details_t_handler_json
   vat_json_object_add_string_copy (node, "sock_filename", mp->sock_filename);
   vat_json_object_add_uint (node, "num_regions", ntohl (mp->num_regions));
   vat_json_object_add_uint (node, "sock_errno", ntohl (mp->sock_errno));
+  vat_json_object_add_uint (node, "mode", mp->operation_mode);
 }
 
 static int
@@ -11379,7 +11433,8 @@ api_sw_interface_vhost_user_dump (vat_main_t * vam)
   vl_api_control_ping_t *mp_ping;
   int ret;
   print (vam->ofp,
-	 "Interface name           idx hdr_sz features server regions filename");
+	 "Interface name            idx hdr_sz features server regions mode"
+	 "      filename");
 
   /* Get list of vhost-user interfaces */
   M (SW_INTERFACE_VHOST_USER_DUMP, mp);
@@ -18492,10 +18547,12 @@ _(l2_interface_vlan_tag_rewrite,                                        \
   "[translate-2-[1|2]] [push_dot1q 0] tag1 <nn> tag2 <nn>")             \
 _(create_vhost_user_if,                                                 \
         "socket <filename> [server] [renumber <dev_instance>] "         \
-        "[mac <mac_address>]")                                          \
+        "[mac <mac_address>] "                                          \
+        "[mode <interrupt | polling>]")                                 \
 _(modify_vhost_user_if,                                                 \
         "<intfc> | sw_if_index <nn> socket <filename>\n"                \
-        "[server] [renumber <dev_instance>]")                           \
+        "[server] [renumber <dev_instance>] "                           \
+        "[mode <interrupt | polling>]")                                 \
 _(delete_vhost_user_if, "<intfc> | sw_if_index <nn>")                   \
 _(sw_interface_vhost_user_dump, "")                                     \
 _(show_version, "")                                                     \