[Qemu-devel] [PATCH COLO-Frame v5 21/29] COLO NIC: Some init work related with proxy module

[zhanghailiang]

Implement communication protocol with proxy module by using
nfnetlink, which requires libnfnetlink libs.

Tell proxy module to do initialization work and moreover ask
kernel to acknowledge the request. It's is necessary for the first
time because Netlink is not a reliable protocol.

Signed-off-by: zhanghailiang <address@hidden>
Signed-off-by: Li Zhijian <address@hidden>
---
 configure      |  22 +++++++-
 net/colo-nic.c | 156 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 176 insertions(+), 2 deletions(-)

diff --git a/configure b/configure
index 793fd12..6676823 100755
--- a/configure
+++ b/configure
@@ -2303,7 +2303,25 @@ EOF
     rdma="no"
   fi
 fi
-
+##########################################
+# COLO needs libnfnetlink libraries
+if test "$colo" != "no"; then
+  cat > $TMPC <<EOF
+#include <libnfnetlink/libnfnetlink.h>
+int main(void) { return 0; }
+EOF
+  colo_libs="-lnfnetlink"
+  if compile_prog "" "$colo_libs"; then
+    colo="yes"
+    libs_softmmu="$libs_softmmu $colo_libs"
+  else
+    if test "$colo" = "yes" ; then
+        error_exit "libnfnetlink is required for colo feature." \
+            "Make sure to have the libnfnetlink devel and headers installed."
+    fi
+    colo="no"
+  fi
+fi
 ##########################################
 # VNC TLS/WS detection
 if test "$vnc" = "yes" -a \( "$vnc_tls" != "no" -o "$vnc_ws" != "no" \) ; then
@@ -2610,7 +2628,7 @@ EOF
     if compile_prog "$cfl" "$lib" ; then
         :
     else
-        error_exit "$drv check failed" \
+        rror_exit "$drv check failed" \
             "Make sure to have the $drv libs and headers installed."
     fi
 }
diff --git a/net/colo-nic.c b/net/colo-nic.c
index fee2cfe..f4e04af 100644
--- a/net/colo-nic.c
+++ b/net/colo-nic.c
@@ -10,12 +10,64 @@
  * later.  See the COPYING file in the top-level directory.
  *
  */
+#include <sys/ioctl.h>
+#include <sys/socket.h>
+#include <linux/netlink.h>
+#include <libnfnetlink/libnfnetlink.h>
+#include <netinet/in.h>
+#include <sys/socket.h>
 #include "include/migration/migration.h"
 #include "migration/migration-colo.h"
 #include "net/net.h"
 #include "net/colo-nic.h"
 #include "qemu/error-report.h"
 
+/* Remove the follow define after proxy is merged into kernel,
+* using #include <libnfnetlink/libnfnetlink.h> instead.
+*/
+#define NFNL_SUBSYS_COLO 12
+
+/* Message Format
+* <---NLMSG_ALIGN(hlen)-----><-------------- NLMSG_ALIGN(len)----------------->
+* +--------------------+- - -+- - - - - - - - - - - - - - +- - - - - - + - - -+
+* |       Header       | Pad |   Netfilter Netlink Header | Attributes | Pad  |
+* |    struct nlmsghdr |     |     struct nfgenmsg        |            |      |
+* +--------------------+- - -+- - - - - - - - - - - - - - + - - - - - -+ - - -+
+*/
+
+enum nfnl_colo_msg_types {
+    NFCOLO_KERNEL_NOTIFY, /* Used by proxy module to notify qemu */
+
+    NFCOLO_DO_CHECKPOINT,
+    NFCOLO_DO_FAILOVER,
+    NFCOLO_PROXY_INIT,
+    NFCOLO_PROXY_RESET,
+
+    NFCOLO_MSG_MAX
+};
+
+enum nfnl_colo_kernel_notify_attributes {
+    NFNL_COLO_KERNEL_NOTIFY_UNSPEC,
+    NFNL_COLO_COMPARE_RESULT,
+    __NFNL_COLO_KERNEL_NOTIFY_MAX
+};
+
+#define NFNL_COLO_KERNEL_NOTIFY_MAX  (__NFNL_COLO_KERNEL_NOTIFY_MAX - 1)
+
+enum nfnl_colo_attributes {
+    NFNL_COLO_UNSPEC,
+    NFNL_COLO_MODE,
+    __NFNL_COLO_MAX
+};
+#define NFNL_COLO_MAX  (__NFNL_COLO_MAX - 1)
+
+struct nfcolo_msg_mode {
+    u_int8_t mode;
+};
+
+struct nfcolo_packet_compare { /* Unused */
+    int32_t different;
+};
 
 typedef struct nic_device {
     NetClientState *nc;
@@ -25,6 +77,9 @@ typedef struct nic_device {
     bool is_up;
 } nic_device;
 
+static struct nfnl_handle *nfnlh;
+static struct nfnl_subsys_handle *nfnlssh;
+
 QTAILQ_HEAD(, nic_device) nic_devices = QTAILQ_HEAD_INITIALIZER(nic_devices);
 
 /*
@@ -177,19 +232,120 @@ void colo_remove_nic_devices(NetClientState *nc)
     }
 }
 
+static int colo_proxy_send(enum nfnl_colo_msg_types msg_type,
+                           enum colo_mode mode, int flag, void *unused)
+{
+    struct nfcolo_msg_mode params;
+    union {
+        char buf[NFNL_HEADER_LEN
+                 + NFA_LENGTH(sizeof(struct nfcolo_msg_mode))];
+        struct nlmsghdr nmh;
+    } u;
+    int ret;
+
+    if (!nfnlssh || !nfnlh) {
+        error_report("nfnlssh and nfnlh are uninited");
+        return -1;
+    }
+    nfnl_fill_hdr(nfnlssh, &u.nmh, 0, AF_UNSPEC, 1,
+                  msg_type, NLM_F_REQUEST | flag);
+    params.mode = mode;
+    u.nmh.nlmsg_pid = nfnl_portid(nfnlh);
+    ret = nfnl_addattr_l(&u.nmh, sizeof(u),  NFNL_COLO_MODE, &params,
+                         sizeof(params));
+    if (ret < 0) {
+        error_report("call nfnl_addattr_l failed");
+        return ret;
+    }
+    ret = nfnl_send(nfnlh, &u.nmh);
+    if (ret < 0) {
+        error_report("call nfnl_send failed");
+    }
+    return ret;
+}
+
+static int check_proxy_ack(void)
+{
+    unsigned char *buf = g_malloc0(2048);
+    struct nlmsghdr *nlmsg;
+    int len;
+    int ret = -1;
+
+    len = nfnl_recv(nfnlh, buf, 2048);
+    if (len <= 0) {
+        error_report("nfnl_recv received nothing");
+        goto err;
+    }
+    nlmsg = (struct nlmsghdr *)buf;
+
+    if (nlmsg->nlmsg_type == NLMSG_ERROR) {
+        struct nlmsgerr *err = (struct nlmsgerr *)NLMSG_DATA(nlmsg);
+
+        if (err->error) {
+            error_report("Received error message:%d",  -err->error);
+            goto err;
+        }
+    }
+
+    ret = 0;
+err:
+    g_free(buf);
+    return ret;
+}
+
 int colo_proxy_init(enum colo_mode mode)
 {
     int ret = -1;
 
+    nfnlh = nfnl_open();
+    if (!nfnlh) {
+        error_report("call nfnl_open failed");
+        return -1;
+    }
+    /* Note:
+     *  Here we must ensure that the nl_pid (also nlmsg_pid in nlmsghdr ) equal
+     *  to the process ID of VM, becase we use it to identify the VM in proxy
+     *  module.
+     */
+    if (nfnl_portid(nfnlh) != getpid()) {
+        error_report("More than one netlink of NETLINK_NETFILTER type exist");
+        return -1;
+    }
+    /* disable netlink sequence tracking by default */
+    nfnl_unset_sequence_tracking(nfnlh);
+    nfnlssh = nfnl_subsys_open(nfnlh, NFNL_SUBSYS_COLO, NFCOLO_MSG_MAX, 0);
+    if (!nfnlssh) {
+        error_report("call nfnl_subsys_open failed");
+        goto err_out;
+    }
+
+    /* Netlink is not a reliable protocol, So it is necessary to request proxy
+     * module to acknowledge in the first time.
+     */
+    ret = colo_proxy_send(NFCOLO_PROXY_INIT, mode, NLM_F_ACK, NULL);
+    if (ret < 0) {
+        goto err_out;
+    }
+
+    ret = check_proxy_ack();
+    if (ret < 0) {
+        goto err_out;
+    }
+
     ret = configure_nic(mode, getpid());
     if (ret != 0) {
         error_report("excute colo-proxy-script failed");
+        goto err_out;
     }
 
+    return 0;
+err_out:
+    nfnl_close(nfnlh);
     return ret;
 }
 
 void colo_proxy_destroy(enum colo_mode mode)
 {
+    nfnl_close(nfnlh);
     teardown_nic(mode, getpid());
 }
-- 
1.7.12.4