X-Git-Url: https://gerrit.fd.io/r/gitweb?a=blobdiff_plain;f=src%2Fvnet%2Fdevices%2Fvirtio%2Fvhost-user.c;h=9244776572627234363121b7ff8790f27c6f62b6;hb=d723161;hp=5fe378cb771f3a3e2ecb13d6ebad6c33ef5d8a9f;hpb=49a04b9545de22beaef5218d3985896d6ba37982;p=vpp.git

diff --git a/src/vnet/devices/virtio/vhost-user.c b/src/vnet/devices/virtio/vhost-user.c
index 5fe378cb771..92447765726 100644
--- a/src/vnet/devices/virtio/vhost-user.c
+++ b/src/vnet/devices/virtio/vhost-user.c
@@ -86,11 +86,22 @@
  * The value 64 was obtained by testing (48 and 128 were not as good).
  */
 #define VHOST_USER_RX_COPY_THRESHOLD 64
+/*
+ * On the transmit side, we keep processing the buffers from vlib in the while
+ * loop and prepare the copy order to be executed later. However, the static
+ * array which we keep the copy order is limited to VHOST_USER_COPY_ARRAY_N
+ * entries. In order to not corrupt memory, we have to do the copy when the
+ * static array reaches the copy threshold. We subtract 40 in case the code
+ * goes into the inner loop for a maximum of 64k frames which may require
+ * more array entries.
+ */
+#define VHOST_USER_TX_COPY_THRESHOLD (VHOST_USER_COPY_ARRAY_N - 40)
 
-#define UNIX_GET_FD(unixfd_idx) \
-    (unixfd_idx != ~0) ? \
-	pool_elt_at_index (unix_main.file_pool, \
-			   unixfd_idx)->file_descriptor : -1;
+#define UNIX_GET_FD(unixfd_idx) ({ \
+    typeof(unixfd_idx) __unixfd_idx = (unixfd_idx); \
+    (__unixfd_idx != ~0) ? \
+	pool_elt_at_index (file_main.file_pool, \
+			   __unixfd_idx)->file_descriptor : -1; })
 
 #define foreach_virtio_trace_flags \
   _ (SIMPLE_CHAINED, 0, "Simple descriptor chaining") \
@@ -237,8 +248,8 @@ map_guest_mem (vhost_user_intf_t * vui, uword addr, u32 * hint)
   r = _mm_blend_epi16 (r, _mm_and_si128 (rl, rh), 0x88);
 
   r = _mm_shuffle_epi8 (r, _mm_set_epi64x (0, 0x0e060c040a020800));
-  i = __builtin_ctzll (_mm_movemask_epi8 (r) |
-		       (1 << VHOST_MEMORY_MAX_NREGIONS));
+  i = count_trailing_zeros (_mm_movemask_epi8 (r) |
+			    (1 << VHOST_MEMORY_MAX_NREGIONS));
 
   if (i < vui->nregions)
     {
@@ -246,7 +257,76 @@ map_guest_mem (vhost_user_intf_t * vui, uword addr, u32 * hint)
       return (void *) (vui->region_mmap_addr[i] + addr -
 		       vui->regions[i].guest_phys_addr);
     }
+#elif __aarch64__ && __ARM_NEON
+  uint64x2_t al, ah, rl, rh, r;
+  uint32_t u32 = 0;
+
+  al = vdupq_n_u64 (addr + 1);
+  ah = vdupq_n_u64 (addr);
+
+  /*First Iteration */
+  rl = vld1q_u64 (&vui->region_guest_addr_lo[0]);
+  rl = vcgtq_u64 (al, rl);
+  rh = vld1q_u64 (&vui->region_guest_addr_hi[0]);
+  rh = vcgtq_u64 (rh, ah);
+  r = vandq_u64 (rl, rh);
+  u32 |= (vgetq_lane_u8 (vreinterpretq_u8_u64 (r), 0) & 0x1);
+  u32 |= ((vgetq_lane_u8 (vreinterpretq_u8_u64 (r), 8) & 0x1) << 1);
+
+  if (u32)
+    {
+      i = count_trailing_zeros (u32);
+      goto vhost_map_guest_mem_done;
+    }
+
+  /*Second Iteration */
+  rl = vld1q_u64 (&vui->region_guest_addr_lo[2]);
+  rl = vcgtq_u64 (al, rl);
+  rh = vld1q_u64 (&vui->region_guest_addr_hi[2]);
+  rh = vcgtq_u64 (rh, ah);
+  r = vandq_u64 (rl, rh);
+  u32 |= ((vgetq_lane_u8 (vreinterpretq_u8_u64 (r), 0) & 0x1) << 2);
+  u32 |= ((vgetq_lane_u8 (vreinterpretq_u8_u64 (r), 8) & 0x1) << 3);
+
+  if (u32)
+    {
+      i = count_trailing_zeros (u32);
+      goto vhost_map_guest_mem_done;
+    }
 
+  /*Third Iteration */
+  rl = vld1q_u64 (&vui->region_guest_addr_lo[4]);
+  rl = vcgtq_u64 (al, rl);
+  rh = vld1q_u64 (&vui->region_guest_addr_hi[4]);
+  rh = vcgtq_u64 (rh, ah);
+  r = vandq_u64 (rl, rh);
+  u32 |= ((vgetq_lane_u8 (vreinterpretq_u8_u64 (r), 0) & 0x1) << 4);
+  u32 |= ((vgetq_lane_u8 (vreinterpretq_u8_u64 (r), 8) & 0x1) << 5);
+
+  if (u32)
+    {
+      i = count_trailing_zeros (u32);
+      goto vhost_map_guest_mem_done;
+    }
+
+  /*Fourth Iteration */
+  rl = vld1q_u64 (&vui->region_guest_addr_lo[6]);
+  rl = vcgtq_u64 (al, rl);
+  rh = vld1q_u64 (&vui->region_guest_addr_hi[6]);
+  rh = vcgtq_u64 (rh, ah);
+  r = vandq_u64 (rl, rh);
+  u32 |= ((vgetq_lane_u8 (vreinterpretq_u8_u64 (r), 0) & 0x1) << 6);
+  u32 |= ((vgetq_lane_u8 (vreinterpretq_u8_u64 (r), 8) & 0x1) << 7);
+
+  i = count_trailing_zeros (u32 | (1 << VHOST_MEMORY_MAX_NREGIONS));
+
+vhost_map_guest_mem_done:
+  if (i < vui->nregions)
+    {
+      *hint = i;
+      return (void *) (vui->region_mmap_addr[i] + addr -
+		       vui->regions[i].guest_phys_addr);
+    }
 #else
   for (i = 0; i < vui->nregions; i++)
     {
@@ -296,7 +376,7 @@ unmap_all_mem_regions (vhost_user_intf_t * vui)
   int i, r;
   for (i = 0; i < vui->nregions; i++)
     {
-      if (vui->region_mmap_addr[i] != (void *) -1)
+      if (vui->region_mmap_addr[i] != MAP_FAILED)
 	{
 
 	  long page_sz = get_huge_page_size (vui->region_mmap_fd[i]);
@@ -313,7 +393,7 @@ unmap_all_mem_regions (vhost_user_intf_t * vui)
 	    ("unmap memory region %d addr 0x%lx len 0x%lx page_sz 0x%x", i,
 	     vui->region_mmap_addr[i], map_sz, page_sz);
 
-	  vui->region_mmap_addr[i] = (void *) -1;
+	  vui->region_mmap_addr[i] = MAP_FAILED;
 
 	  if (r == -1)
 	    {
@@ -477,7 +557,7 @@ vhost_user_set_interrupt_pending (vhost_user_intf_t * vui, u32 ifq)
 }
 
 static clib_error_t *
-vhost_user_callfd_read_ready (unix_file_t * uf)
+vhost_user_callfd_read_ready (clib_file_t * uf)
 {
   __attribute__ ((unused)) int n;
   u8 buff[8];
@@ -488,7 +568,7 @@ vhost_user_callfd_read_ready (unix_file_t * uf)
 }
 
 static clib_error_t *
-vhost_user_kickfd_read_ready (unix_file_t * uf)
+vhost_user_kickfd_read_ready (clib_file_t * uf)
 {
   __attribute__ ((unused)) int n;
   u8 buff[8];
@@ -569,16 +649,16 @@ vhost_user_vring_close (vhost_user_intf_t * vui, u32 qid)
   vhost_user_vring_t *vring = &vui->vrings[qid];
   if (vring->kickfd_idx != ~0)
     {
-      unix_file_t *uf = pool_elt_at_index (unix_main.file_pool,
+      clib_file_t *uf = pool_elt_at_index (file_main.file_pool,
 					   vring->kickfd_idx);
-      unix_file_del (&unix_main, uf);
+      clib_file_del (&file_main, uf);
       vring->kickfd_idx = ~0;
     }
   if (vring->callfd_idx != ~0)
     {
-      unix_file_t *uf = pool_elt_at_index (unix_main.file_pool,
+      clib_file_t *uf = pool_elt_at_index (file_main.file_pool,
 					   vring->callfd_idx);
-      unix_file_del (&unix_main, uf);
+      clib_file_del (&file_main, uf);
       vring->callfd_idx = ~0;
     }
   if (vring->errfd != -1)
@@ -597,10 +677,10 @@ vhost_user_if_disconnect (vhost_user_intf_t * vui)
 
   vnet_hw_interface_set_flags (vnm, vui->hw_if_index, 0);
 
-  if (vui->unix_file_index != ~0)
+  if (vui->clib_file_index != ~0)
     {
-      unix_file_del (&unix_main, unix_main.file_pool + vui->unix_file_index);
-      vui->unix_file_index = ~0;
+      clib_file_del (&file_main, file_main.file_pool + vui->clib_file_index);
+      vui->clib_file_index = ~0;
     }
 
   vui->is_up = 0;
@@ -654,7 +734,7 @@ vhost_user_log_dirty_pages (vhost_user_intf_t * vui, u64 addr, u64 len)
   }
 
 static clib_error_t *
-vhost_user_socket_read (unix_file_t * uf)
+vhost_user_socket_read (clib_file_t * uf)
 {
   int n, i;
   int fd, number_of_fds = 0;
@@ -666,7 +746,7 @@ vhost_user_socket_read (unix_file_t * uf)
   vhost_user_intf_t *vui;
   struct cmsghdr *cmsg;
   u8 q;
-  unix_file_t template = { 0 };
+  clib_file_t template = { 0 };
   vnet_main_t *vnm = vnet_get_main ();
 
   vui = pool_elt_at_index (vum->vhost_user_interfaces, uf->private_data);
@@ -819,7 +899,7 @@ vhost_user_socket_read (unix_file_t * uf)
 
 	  long page_sz = get_huge_page_size (fds[i]);
 
-	  /* align size to 2M page */
+	  /* align size to page */
 	  ssize_t map_sz = (vui->regions[i].memory_size +
 			    vui->regions[i].mmap_offset +
 			    page_sz - 1) & ~(page_sz - 1);
@@ -842,8 +922,9 @@ vhost_user_socket_read (unix_file_t * uf)
 	    }
 	  vui->region_mmap_addr[i] += vui->regions[i].mmap_offset;
 	  vui->region_mmap_fd[i] = fds[i];
+
+	  vui->nregions++;
 	}
-      vui->nregions = msg.memory.nregions;
       break;
 
     case VHOST_USER_SET_VRING_NUM:
@@ -927,9 +1008,9 @@ vhost_user_socket_read (unix_file_t * uf)
       /* if there is old fd, delete and close it */
       if (vui->vrings[q].callfd_idx != ~0)
 	{
-	  unix_file_t *uf = pool_elt_at_index (unix_main.file_pool,
+	  clib_file_t *uf = pool_elt_at_index (file_main.file_pool,
 					       vui->vrings[q].callfd_idx);
-	  unix_file_del (&unix_main, uf);
+	  clib_file_del (&file_main, uf);
 	  vui->vrings[q].callfd_idx = ~0;
 	}
 
@@ -945,7 +1026,7 @@ vhost_user_socket_read (unix_file_t * uf)
 	  template.file_descriptor = fds[0];
 	  template.private_data =
 	    ((vui - vhost_user_main.vhost_user_interfaces) << 8) + q;
-	  vui->vrings[q].callfd_idx = unix_file_add (&unix_main, &template);
+	  vui->vrings[q].callfd_idx = clib_file_add (&file_main, &template);
 	}
       else
 	vui->vrings[q].callfd_idx = ~0;
@@ -959,9 +1040,9 @@ vhost_user_socket_read (unix_file_t * uf)
 
       if (vui->vrings[q].kickfd_idx != ~0)
 	{
-	  unix_file_t *uf = pool_elt_at_index (unix_main.file_pool,
+	  clib_file_t *uf = pool_elt_at_index (file_main.file_pool,
 					       vui->vrings[q].kickfd_idx);
-	  unix_file_del (&unix_main, uf);
+	  clib_file_del (&file_main, uf);
 	  vui->vrings[q].kickfd_idx = ~0;
 	}
 
@@ -978,7 +1059,7 @@ vhost_user_socket_read (unix_file_t * uf)
 	  template.private_data =
 	    (((uword) (vui - vhost_user_main.vhost_user_interfaces)) << 8) +
 	    q;
-	  vui->vrings[q].kickfd_idx = unix_file_add (&unix_main, &template);
+	  vui->vrings[q].kickfd_idx = clib_file_add (&file_main, &template);
 	}
       else
 	{
@@ -1065,7 +1146,7 @@ vhost_user_socket_read (unix_file_t * uf)
 	  }
 
 	fd = fds[0];
-	/* align size to 2M page */
+	/* align size to page */
 	long page_sz = get_huge_page_size (fd);
 	ssize_t map_sz =
 	  (msg.log.size + msg.log.offset + page_sz - 1) & ~(page_sz - 1);
@@ -1168,7 +1249,7 @@ close_socket:
 }
 
 static clib_error_t *
-vhost_user_socket_error (unix_file_t * uf)
+vhost_user_socket_error (clib_file_t * uf)
 {
   vlib_main_t *vm = vlib_get_main ();
   vhost_user_main_t *vum = &vhost_user_main;
@@ -1184,11 +1265,11 @@ vhost_user_socket_error (unix_file_t * uf)
 }
 
 static clib_error_t *
-vhost_user_socksvr_accept_ready (unix_file_t * uf)
+vhost_user_socksvr_accept_ready (clib_file_t * uf)
 {
   int client_fd, client_len;
   struct sockaddr_un client;
-  unix_file_t template = { 0 };
+  clib_file_t template = { 0 };
   vhost_user_main_t *vum = &vhost_user_main;
   vhost_user_intf_t *vui;
 
@@ -1202,12 +1283,20 @@ vhost_user_socksvr_accept_ready (unix_file_t * uf)
   if (client_fd < 0)
     return clib_error_return_unix (0, "accept");
 
-  DBG_SOCK ("New client socket for vhost interface %d", vui->sw_if_index);
+  if (vui->clib_file_index != ~0)
+    {
+      DBG_SOCK ("Close client socket for vhost interface %d, fd %d",
+		vui->sw_if_index, UNIX_GET_FD (vui->clib_file_index));
+      clib_file_del (&file_main, file_main.file_pool + vui->clib_file_index);
+    }
+
+  DBG_SOCK ("New client socket for vhost interface %d, fd %d",
+	    vui->sw_if_index, client_fd);
   template.read_function = vhost_user_socket_read;
   template.error_function = vhost_user_socket_error;
   template.file_descriptor = client_fd;
   template.private_data = vui - vhost_user_main.vhost_user_interfaces;
-  vui->unix_file_index = unix_file_add (&unix_main, &template);
+  vui->clib_file_index = clib_file_add (&file_main, &template);
   return 0;
 }
 
@@ -1257,7 +1346,7 @@ format_vhost_trace (u8 * s, va_list * va)
 
   vnet_sw_interface_t *sw = vnet_get_sw_interface (vnm, vui->sw_if_index);
 
-  uword indent = format_get_indent (s);
+  u32 indent = format_get_indent (s);
 
   s = format (s, "%U %U queue %d\n", format_white_space, indent,
 	      format_vnet_sw_interface_name, vnm, sw, t->qid);
@@ -1545,8 +1634,10 @@ vhost_user_if_input (vlib_main_t * vm,
    * per packet. In case packets are bigger, we will just yeld at some point
    * in the loop and come back later. This is not an issue as for big packet,
    * processing cost really comes from the memory copy.
+   * The assumption is that big packets will fit in 40 buffers.
    */
-  if (PREDICT_FALSE (vum->cpus[thread_index].rx_buffers_len < n_left + 1))
+  if (PREDICT_FALSE (vum->cpus[thread_index].rx_buffers_len < n_left + 1 ||
+		     vum->cpus[thread_index].rx_buffers_len < 40))
     {
       u32 curr_len = vum->cpus[thread_index].rx_buffers_len;
       vum->cpus[thread_index].rx_buffers_len +=
@@ -1998,7 +2089,7 @@ vhost_user_tx (vlib_main_t * vm,
 
   qid =
     VHOST_VRING_IDX_RX (*vec_elt_at_index
-			(vui->per_cpu_tx_qid, vlib_get_thread_index ()));
+			(vui->per_cpu_tx_qid, thread_index));
   rxvq = &vui->vrings[qid];
   if (PREDICT_FALSE (vui->use_tx_spinlock))
     vhost_user_vring_lock (vui, qid);
@@ -2210,6 +2301,27 @@ retry:
 	}
 
       n_left--;			//At the end for error counting when 'goto done' is invoked
+
+      /*
+       * Do the copy periodically to prevent
+       * vum->cpus[thread_index].copy array overflow and corrupt memory
+       */
+      if (PREDICT_FALSE (copy_len >= VHOST_USER_TX_COPY_THRESHOLD))
+	{
+	  if (PREDICT_FALSE
+	      (vhost_user_tx_copy (vui, vum->cpus[thread_index].copy,
+				   copy_len, &map_hint)))
+	    {
+	      vlib_error_count (vm, node->node_index,
+				VHOST_USER_TX_FUNC_ERROR_MMAP_FAIL, 1);
+	    }
+	  copy_len = 0;
+
+	  /* give buffers back to driver */
+	  CLIB_MEMORY_BARRIER ();
+	  rxvq->used->idx = rxvq->last_used_idx;
+	  vhost_user_log_dirty_ring (vui, rxvq, idx);
+	}
       buffers++;
     }
 
@@ -2264,7 +2376,7 @@ done3:
       vlib_increment_simple_counter
 	(vnet_main.interface_main.sw_if_counters
 	 + VNET_INTERFACE_COUNTER_DROP,
-	 vlib_get_thread_index (), vui->sw_if_index, n_left);
+	 thread_index, vui->sw_if_index, n_left);
     }
 
   vlib_buffer_free (vm, vlib_frame_args (frame), frame->n_vectors);
@@ -2436,16 +2548,14 @@ vhost_user_interface_admin_up_down (vnet_main_t * vnm, u32 hw_if_index,
 				    u32 flags)
 {
   vnet_hw_interface_t *hif = vnet_get_hw_interface (vnm, hw_if_index);
-  uword is_up = (flags & VNET_SW_INTERFACE_FLAG_ADMIN_UP) != 0;
   vhost_user_main_t *vum = &vhost_user_main;
   vhost_user_intf_t *vui =
     pool_elt_at_index (vum->vhost_user_interfaces, hif->dev_instance);
+  u32 hw_flags = 0;
+  vui->admin_up = (flags & VNET_SW_INTERFACE_FLAG_ADMIN_UP) != 0;
+  hw_flags = vui->admin_up ? VNET_HW_INTERFACE_FLAG_LINK_UP : 0;
 
-  vui->admin_up = is_up;
-
-  if (is_up)
-    vnet_hw_interface_set_flags (vnm, vui->hw_if_index,
-				 VNET_HW_INTERFACE_FLAG_LINK_UP);
+  vnet_hw_interface_set_flags (vnm, vui->hw_if_index, hw_flags);
 
   return /* no error */ 0;
 }
@@ -2475,7 +2585,7 @@ vhost_user_process (vlib_main_t * vm,
   vhost_user_intf_t *vui;
   struct sockaddr_un sun;
   int sockfd;
-  unix_file_t template = { 0 };
+  clib_file_t template = { 0 };
   f64 timeout = 3153600000.0 /* 100 years */ ;
   uword *event_data = 0;
 
@@ -2496,7 +2606,7 @@ vhost_user_process (vlib_main_t * vm,
       pool_foreach (vui, vum->vhost_user_interfaces, {
 
 	  if (vui->unix_server_index == ~0) { //Nothing to do for server sockets
-	      if (vui->unix_file_index == ~0)
+	      if (vui->clib_file_index == ~0)
 		{
 		  if ((sockfd < 0) &&
 		      ((sockfd = socket (AF_UNIX, SOCK_STREAM, 0)) < 0))
@@ -2534,7 +2644,7 @@ vhost_user_process (vlib_main_t * vm,
 		      template.file_descriptor = sockfd;
 		      template.private_data =
 			  vui - vhost_user_main.vhost_user_interfaces;
-		      vui->unix_file_index = unix_file_add (&unix_main, &template);
+		      vui->clib_file_index = clib_file_add (&file_main, &template);
 
 		      /* This sockfd is considered consumed */
 		      sockfd = -1;
@@ -2549,7 +2659,7 @@ vhost_user_process (vlib_main_t * vm,
 		  /* check if socket is alive */
 		  int error = 0;
 		  socklen_t len = sizeof (error);
-		  int fd = UNIX_GET_FD(vui->unix_file_index);
+		  int fd = UNIX_GET_FD(vui->clib_file_index);
 		  int retval =
 		      getsockopt (fd, SOL_SOCKET, SO_ERROR, &error, &len);
 
@@ -2596,9 +2706,9 @@ vhost_user_term_if (vhost_user_intf_t * vui)
   if (vui->unix_server_index != ~0)
     {
       //Close server socket
-      unix_file_t *uf = pool_elt_at_index (unix_main.file_pool,
+      clib_file_t *uf = pool_elt_at_index (file_main.file_pool,
 					   vui->unix_server_index);
-      unix_file_del (&unix_main, uf);
+      clib_file_del (&file_main, uf);
       vui->unix_server_index = ~0;
       unlink (vui->sock_filename);
     }
@@ -2757,8 +2867,7 @@ vhost_user_create_ethernet (vnet_main_t * vnm, vlib_main_t * vm,
   if (error)
     clib_error_report (error);
 
-  vnet_hw_interface_t *hi = vnet_get_hw_interface (vnm, vui->hw_if_index);
-  hi->max_l3_packet_bytes[VLIB_RX] = hi->max_l3_packet_bytes[VLIB_TX] = 9000;
+  vnet_sw_interface_set_mtu (vnm, vui->sw_if_index, 9000);
 }
 
 /*
@@ -2780,11 +2889,11 @@ vhost_user_vui_init (vnet_main_t * vnm,
   sw = vnet_get_hw_sw_interface (vnm, vui->hw_if_index);
   if (server_sock_fd != -1)
     {
-      unix_file_t template = { 0 };
+      clib_file_t template = { 0 };
       template.read_function = vhost_user_socksvr_accept_ready;
       template.file_descriptor = server_sock_fd;
       template.private_data = vui - vum->vhost_user_interfaces;	//hw index
-      vui->unix_server_index = unix_file_add (&unix_main, &template);
+      vui->unix_server_index = clib_file_add (&file_main, &template);
     }
   else
     {
@@ -2797,7 +2906,7 @@ vhost_user_vui_init (vnet_main_t * vnm,
   vui->sock_errno = 0;
   vui->is_up = 0;
   vui->feature_mask = feature_mask;
-  vui->unix_file_index = ~0;
+  vui->clib_file_index = ~0;
   vui->log_base_addr = 0;
   vui->if_index = vui - vum->vhost_user_interfaces;
   mhash_set_mem (&vum->if_index_by_sock_name, vui->sock_filename,
@@ -3141,6 +3250,13 @@ show_vhost_user_command_fn (vlib_main_t * vm,
       if (unformat
 	  (input, "%U", unformat_vnet_hw_interface, vnm, &hw_if_index))
 	{
+	  hi = vnet_get_hw_interface (vnm, hw_if_index);
+	  if (vhost_user_dev_class.index != hi->dev_class_index)
+	    {
+	      error = clib_error_return (0, "unknown input `%U'",
+					 format_unformat_error, input);
+	      goto done;
+	    }
 	  vec_add1 (hw_if_indices, hw_if_index);
 	}
       else if (unformat (input, "descriptors") || unformat (input, "desc"))
@@ -3321,16 +3437,23 @@ done:
  *
  * There are several parameters associated with a vHost interface:
  *
- * - <b>socket <socket-filename></b> - Name of the linux socket used by QEMU/VM and
- * VPP to manage the vHost interface. If socket does not already exist, VPP will
- * create the socket.
+ * - <b>socket <socket-filename></b> - Name of the linux socket used by hypervisor
+ * and VPP to manage the vHost interface. If in '<em>server</em>' mode, VPP will
+ * create the socket if it does not already exist. If in '<em>client</em>' mode,
+ * hypervisor will create the socket if it does not already exist. The VPP code
+ * is indifferent to the file location. However, if SELinux is enabled, then the
+ * socket needs to be created in '<em>/var/run/vpp/</em>'.
  *
- * - <b>server</b> - Optional flag to indicate that VPP should be the server for the
- * linux socket. If not provided, VPP will be the client.
+ * - <b>server</b> - Optional flag to indicate that VPP should be the server for
+ * the linux socket. If not provided, VPP will be the client. In '<em>server</em>'
+ *  mode, the VM can be reset without tearing down the vHost Interface. In
+ * '<em>client</em>' mode, VPP can be reset without bringing down the VM and
+ * tearing down the vHost Interface.
  *
  * - <b>feature-mask <hex></b> - Optional virtio/vhost feature set negotiated at
- * startup. By default, all supported features will be advertised. Otherwise,
- * provide the set of features desired.
+ * startup. <b>This is intended for degugging only.</b> It is recommended that this
+ * parameter not be used except by experienced users. By default, all supported
+ * features will be advertised. Otherwise, provide the set of features desired.
  *   - 0x000008000 (15) - VIRTIO_NET_F_MRG_RXBUF
  *   - 0x000020000 (17) - VIRTIO_NET_F_CTRL_VQ
  *   - 0x000200000 (21) - VIRTIO_NET_F_GUEST_ANNOUNCE
@@ -3348,17 +3471,14 @@ done:
  * in the name to be specified. If instance already exists, name will be used
  * anyway and multiple instances will have the same name. Use with caution.
  *
- * - <b>mode [interrupt | polling]</b> - Optional parameter specifying
- * the input thread polling policy.
- *
  * @cliexpar
  * Example of how to create a vhost interface with VPP as the client and all features enabled:
- * @cliexstart{create vhost-user socket /tmp/vhost1.sock}
+ * @cliexstart{create vhost-user socket /var/run/vpp/vhost1.sock}
  * VirtualEthernet0/0/0
  * @cliexend
  * Example of how to create a vhost interface with VPP as the server and with just
  * multiple queues enabled:
- * @cliexstart{create vhost-user socket /tmp/vhost2.sock server feature-mask 0x40400000}
+ * @cliexstart{create vhost-user socket /var/run/vpp/vhost2.sock server feature-mask 0x40400000}
  * VirtualEthernet0/0/1
  * @cliexend
  * Once the vHost interface is created, enable the interface using:
@@ -3417,7 +3537,7 @@ VLIB_CLI_COMMAND (vhost_user_delete_command, static) = {
  *    VHOST_USER_PROTOCOL_F_MQ (0)
  *    VHOST_USER_PROTOCOL_F_LOG_SHMFD (1)
  *
- *  socket filename /tmp/vhost1.sock type client errno "Success"
+ *  socket filename /var/run/vpp/vhost1.sock type client errno "Success"
  *
  * rx placement:
  *    thread 1 on vring 1