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Subject[PATCH 19/21] Drivers: hv: vss: full handshake support
Date
From: Vitaly Kuznetsov <vkuznets@redhat.com>

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>
---
drivers/hv/hv_snapshot.c | 49 ++++++++++++++++++++++++++++++++----------
include/uapi/linux/hyperv.h | 5 ++++
tools/hv/hv_vss_daemon.c | 14 ++++++++++++
3 files changed, 56 insertions(+), 12 deletions(-)

diff --git a/drivers/hv/hv_snapshot.c b/drivers/hv/hv_snapshot.c
index 2c8c246..ee1762b 100644
--- 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 bb1cb73..66c76df 100644
--- 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 36f1821..96234b6 100644
--- 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));
--
1.7.4.1


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