[PATCH 2 of 4 RFC] xl/remus: Network buffering cmdline switch, setup/teardown

[Shriram Rajagopalan <rshriram@cs.ubc.ca>]

Add appropriate code to xl_cmdline.c to setup network buffers for
each vif belonging to the guest.  Also provide a command line switch
to explicitly "enable" network buffering.

Signed-off-by: Shriram Rajagopalan <rshriram@cs.ubc.ca>

diff -r 3ae38cbe535c -r 3cd67f6ff63a tools/libxl/libxl_types.idl
--- a/tools/libxl/libxl_types.idl	Wed Jul 24 22:55:00 2013 -0700
+++ b/tools/libxl/libxl_types.idl	Thu Jul 25 00:02:19 2013 -0700
@@ -521,6 +521,7 @@ libxl_domain_remus_info = Struct("domain
     ("interval",     integer),
     ("blackhole",    bool),
     ("compression",  bool),
+    ("netbuf_iflist", libxl_string_list),
     ])
 
 libxl_event_type = Enumeration("event_type", [
diff -r 3ae38cbe535c -r 3cd67f6ff63a tools/libxl/xl_cmdimpl.c
--- a/tools/libxl/xl_cmdimpl.c	Wed Jul 24 22:55:00 2013 -0700
+++ b/tools/libxl/xl_cmdimpl.c	Thu Jul 25 00:02:19 2013 -0700
@@ -7039,10 +7039,109 @@ done:
     return ret;
 }
 
+static char **get_guest_vifnames(uint32_t domid, int *num_vifs)
+{
+    char **viflist;
+    libxl_device_nic *nics;
+    libxl_nicinfo nicinfo;
+    int nb, i;
+
+    nics = libxl_device_nic_list(ctx, domid, &nb);
+    if (!nics) { *num_vifs = 0; return NULL;}
+
+    viflist = calloc((nb + 1), sizeof(char *));
+    if (!viflist) {
+        perror("failed to allocate memory to hold vif names!");
+        exit(-1);
+    }
+
+    for (i = 0; i < nb; ++i) {
+        if (!libxl_device_nic_getinfo(ctx, domid, &nics[i], &nicinfo))  {
+            if (asprintf(&viflist[i], "vif%u.%d", domid, nicinfo.devid) < 0) {
+                perror("Cannot alloc memory while getting guest vif names");
+                exit(-1);
+            }
+            libxl_nicinfo_dispose(&nicinfo);
+        }
+        libxl_device_nic_dispose(&nics[i]);
+    }
+    free(nics);
+
+    *num_vifs = nb;
+    return viflist;
+}
+
+static int remus_setup_network_buffers(uint32_t domid,
+                                          char ***pifblist, int *num_ifbs)
+{
+
+    char **viflist, **ifblist;
+    int nb, i, j;
+
+    viflist = get_guest_vifnames(domid, &nb);
+    fprintf(stderr, "Domain %u has %d vifs\n", domid, nb);
+
+    if (!viflist) { *num_ifbs = 0; *ifblist = NULL; return 0;}
+
+    ifblist = calloc((nb + 1), sizeof(char *));
+    if (!ifblist) {
+        perror("failed to allocate memory for ifb list!");
+        exit(-1);
+    }
+
+    /* For each vif, install the network buffer */
+    for (i = 0; i < nb; ++i) {
+        ifblist[i] = remus_install_netbuf_on_dev(viflist[i]);
+        if (ifblist[i] == NULL) {
+            fprintf(stderr, "Failed to setup output buffer for interface %s\n",
+                    viflist[i]);
+            break;
+        }
+    }
+
+    if (i < nb) {
+        j = i;
+        remus_uninstall_netbufs(viflist, nb, ifblist, j);
+        for (i = 0; i < nb; i++)
+            free(viflist[i]);
+        free(viflist);
+
+        for (i = 0; i < j; i++)
+            free(ifblist[i]);
+        free(ifblist);
+        *num_ifbs = 0;
+        *pifblist = NULL;
+        return -1;
+    }
+
+    for (i = 0; i < nb; i++)
+        free(viflist[i]);
+    free(viflist);
+
+    *num_ifbs = nb;
+    *pifblist = ifblist;
+    return 0;
+}
+
+static void remus_teardown_network_buffers(uint32_t domid, char **ifblist,
+                                           int num_ifbs)
+{
+    int nb, i;
+    char **viflist;
+ 
+    viflist = get_guest_vifnames(domid, &nb);
+    remus_uninstall_netbufs(viflist, nb, ifblist, num_ifbs);
+
+    for (i = 0; i < nb; i++)
+        free(viflist[i]);
+    free(viflist);
+
+}
+
 int main_remus(int argc, char **argv)
 {
     uint32_t domid;
-    int opt, rc, daemonize = 1;
+    int opt, rc, daemonize = 1, netbuf = 0, num_ifbs = 0;
     const char *ssh_command = "ssh";
     char *host = NULL, *rune = NULL;
     libxl_domain_remus_info r_info;
@@ -7057,7 +7156,7 @@ int main_remus(int argc, char **argv)
     r_info.blackhole = 0;
     r_info.compression = 1;
 
-    SWITCH_FOREACH_OPT(opt, "bui:s:e", NULL, "remus", 2) {
+    SWITCH_FOREACH_OPT(opt, "bui:s:en", NULL, "remus", 2) {
     case 'i':
         r_info.interval = atoi(optarg);
         break;
@@ -7073,6 +7172,9 @@ int main_remus(int argc, char **argv)
     case 'e':
         daemonize = 0;
         break;
+    case 'n':
+        netbuf = 1;
+        break;
     }
 
     domid = find_domain(argv[optind]);
@@ -7109,6 +7211,19 @@ int main_remus(int argc, char **argv)
                             rune);
     }
 
+    if (netbuf) {
+        rc = remus_setup_network_buffers(domid,
+                                         (char ***)(&r_info.netbuf_iflist),
+                                         &num_ifbs);
+        if (rc) {
+            fprintf(stderr, "Failed to properly setup network "
+                    "buffering. Exiting..\n");
+            close(send_fd);
+            return -ERROR_FAIL;
+        } else
+            fprintf(stderr, "Network buffers setup on %d interfaces\n", num_ifbs);
+    }
+
     /* Point of no return */
     rc = libxl_domain_remus_start(ctx, &r_info, domid, send_fd, recv_fd, 0);
 
@@ -7126,6 +7241,9 @@ int main_remus(int argc, char **argv)
         libxl_domain_resume(ctx, domid, 1, 0);
     }
 
+    if (netbuf)
+        remus_teardown_network_buffers(domid, (char **)r_info.netbuf_iflist, num_ifbs);
+
     close(send_fd);
     return -ERROR_FAIL;
 }
diff -r 3ae38cbe535c -r 3cd67f6ff63a tools/libxl/xl_cmdtable.c
--- a/tools/libxl/xl_cmdtable.c	Wed Jul 24 22:55:00 2013 -0700
+++ b/tools/libxl/xl_cmdtable.c	Thu Jul 25 00:02:19 2013 -0700
@@ -485,8 +485,8 @@ struct cmd_spec cmd_table[] = {
       "                        to sh. If empty, run <host> instead of \n"
       "                        ssh <host> xl migrate-receive -r [-e]\n"
       "-e                      Do not wait in the background (on <host>) for the death\n"
-      "                        of the domain."
-
+      "                        of the domain.\n"
+      "-n                      Enable Remus network buffering\n"
     },
 };