Drivers: hv: vss: full handshake support

Introduce VSS_OP_REGISTER1 to support kernel replying to the negotiation
message with its own version.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Tested-by: Alex Ng <alexng@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/hv/hv_snapshot.c b/drivers/hv/hv_snapshot.c
index 2c8c246d09eb7371d0c8711d6f4cf0b033dc00ef..ee1762b39bf2d66ad04d08b8bc64af1aed54fa88 100644 (file)
--- a/drivers/hv/hv_snapshot.c
+++ b/drivers/hv/hv_snapshot.c
@@ -59,6 +59,11 @@ static struct {
 
 static void vss_respond_to_host(int error);
 
+/*
+ * This state maintains the version number registered by the daemon.
+ */
+static int dm_reg_value;
+
 static const char vss_devname[] = "vmbus/hv_vss";
 static __u8 *recv_buffer;
 static struct hvutil_transport *hvt;
@@ -89,6 +94,29 @@ static void vss_timeout_func(struct work_struct *dummy)
                        hv_vss_onchannelcallback);
 }
 
+static int vss_handle_handshake(struct hv_vss_msg *vss_msg)
+{
+       u32 our_ver = VSS_OP_REGISTER1;
+
+       switch (vss_msg->vss_hdr.operation) {
+       case VSS_OP_REGISTER:
+               /* Daemon doesn't expect us to reply */
+               dm_reg_value = VSS_OP_REGISTER;
+               break;
+       case VSS_OP_REGISTER1:
+               /* Daemon expects us to reply with our own version*/
+               if (hvutil_transport_send(hvt, &our_ver, sizeof(our_ver)))
+                       return -EFAULT;
+               dm_reg_value = VSS_OP_REGISTER1;
+               break;
+       default:
+               return -EINVAL;
+       }
+       vss_transaction.state = HVUTIL_READY;
+       pr_info("VSS daemon registered\n");
+       return 0;
+}
+
 static int vss_on_msg(void *msg, int len)
 {
        struct hv_vss_msg *vss_msg = (struct hv_vss_msg *)msg;
@@ -96,18 +124,15 @@ static int vss_on_msg(void *msg, int len)
        if (len != sizeof(*vss_msg))
                return -EINVAL;
 
-       /*
-        * Don't process registration messages if we're in the middle of
-        * a transaction processing.
-        */
-       if (vss_transaction.state > HVUTIL_READY &&
-           vss_msg->vss_hdr.operation == VSS_OP_REGISTER)
-               return -EINVAL;
-
-       if (vss_transaction.state == HVUTIL_DEVICE_INIT &&
-           vss_msg->vss_hdr.operation == VSS_OP_REGISTER) {
-               pr_info("VSS daemon registered\n");
-               vss_transaction.state = HVUTIL_READY;
+       if (vss_msg->vss_hdr.operation == VSS_OP_REGISTER ||
+           vss_msg->vss_hdr.operation == VSS_OP_REGISTER1) {
+               /*
+                * Don't process registration messages if we're in the middle
+                * of a transaction processing.
+                */
+               if (vss_transaction.state > HVUTIL_READY)
+                       return -EINVAL;
+               return vss_handle_handshake(vss_msg);
        } else if (vss_transaction.state == HVUTIL_USERSPACE_REQ) {
                vss_transaction.state = HVUTIL_USERSPACE_RECV;
                if (cancel_delayed_work_sync(&vss_timeout_work)) {

diff --git a/include/uapi/linux/hyperv.h b/include/uapi/linux/hyperv.h
index bb1cb73c927ae78c84e3ea5a7f253be6040cfed7..66c76df2c32d4368d015c956c5b60ab433423b4e 100644 (file)
--- a/include/uapi/linux/hyperv.h
+++ b/include/uapi/linux/hyperv.h
@@ -45,6 +45,11 @@
 
 #define VSS_OP_REGISTER 128
 
+/*
+  Daemon code with full handshake support.
+ */
+#define VSS_OP_REGISTER1 129
+
 enum hv_vss_op {
        VSS_OP_CREATE = 0,
        VSS_OP_DELETE,

diff --git a/tools/hv/hv_vss_daemon.c b/tools/hv/hv_vss_daemon.c
index 36f18211afa7a1e18bee2fb757ce636fc6866936..96234b638249e6f7c2ecb1c4820b62a7abefdd4c 100644 (file)
--- a/tools/hv/hv_vss_daemon.c
+++ b/tools/hv/hv_vss_daemon.c
@@ -148,6 +148,8 @@ int main(int argc, char *argv[])
        int     op;
        struct hv_vss_msg vss_msg[1];
        int daemonize = 1, long_index = 0, opt;
+       int in_handshake = 1;
+       __u32 kernel_modver;
 
        static struct option long_options[] = {
                {"help",        no_argument,       0,  'h' },
@@ -211,6 +213,18 @@ int main(int argc, char *argv[])
 
                len = read(vss_fd, vss_msg, sizeof(struct hv_vss_msg));
 
+               if (in_handshake) {
+                       if (len != sizeof(kernel_modver)) {
+                               syslog(LOG_ERR, "invalid version negotiation");
+                               exit(EXIT_FAILURE);
+                       }
+                       kernel_modver = *(__u32 *)vss_msg;
+                       in_handshake = 0;
+                       syslog(LOG_INFO, "VSS: kernel module version: %d",
+                              kernel_modver);
+                       continue;
+               }
+
                if (len != sizeof(struct hv_vss_msg)) {
                        syslog(LOG_ERR, "read failed; error:%d %s",
                               errno, strerror(errno));