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Subject[PATCH 1/1] Drivers: hv: vmbus: enable VMBus protocol version 5.0
Date
From: Dexuan Cui <decui@microsoft.com>

With VMBus protocol 5.0, we're able to better support new features, e.g.
running two or more VMBus drivers simultaneously in a single VM -- note:
we can't simply load the current VMBus driver twice, instead, a secondary
VMBus driver must be implemented.

This patch adds the support for the new VMBus protocol, which is available
on new Windows hosts, by:

1) We still use SINT2 for compatibility;
2) We must use Connection ID 4 for the Initiate Contact Message, and for
subsequent messages, we must use the Message Connection ID field in
the host-returned VersionResponse Message.

Notes for developers of the secondary VMBus driver:
1) Must use VMBus protocol 5.0 as well;
2) Must use a different SINT number that is not in use.
3) Must use Connection ID 4 for the Initiate Contact Message, and for
subsequent messages, must use the Message Connection ID field in
the host-returned VersionResponse Message.
4) It's possible that the primary VMBus driver using protocol version 4.0
can work with a secondary VMBus driver using protocol version 5.0, but it's
recommended that both should use 5.0 for new Hyper-V features in the future.

Signed-off-by: Dexuan Cui <decui@microsoft.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: K. Y. Srinivasan <kys@microsoft.com>
Cc: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
---
drivers/hv/connection.c | 44 ++++++++++++++++++++++++++++++++++++++++++--
drivers/hv/hyperv_vmbus.h | 3 +++
include/linux/hyperv.h | 26 ++++++++++++++++++++++++--
3 files changed, 69 insertions(+), 4 deletions(-)

diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
index 72855182b191..19e046820fda 100644
--- a/drivers/hv/connection.c
+++ b/drivers/hv/connection.c
@@ -63,6 +63,9 @@ static __u32 vmbus_get_next_version(__u32 current_version)
case (VERSION_WIN10):
return VERSION_WIN8_1;

+ case (VERSION_WIN10_V5):
+ return VERSION_WIN10;
+
case (VERSION_WS2008):
default:
return VERSION_INVAL;
@@ -80,9 +83,29 @@ static int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo,

msg = (struct vmbus_channel_initiate_contact *)msginfo->msg;

+ memset(msg, 0, sizeof(*msg));
msg->header.msgtype = CHANNELMSG_INITIATE_CONTACT;
msg->vmbus_version_requested = version;
- msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
+
+ /*
+ * VMBus protocol 5.0 (VERSION_WIN10_V5) requires that we must use
+ * VMBUS_MESSAGE_CONNECTION_ID_4 for the Initiate Contact Message,
+ * and for subsequent messages, we must use the Message Connection ID
+ * field in the host-returned Version Response Message. And, with
+ * VERSION_WIN10_V5, we don't use msg->interrupt_page, but we tell
+ * the host explicitly that we still use VMBUS_MESSAGE_SINT(2) for
+ * compatibility.
+ *
+ * On old hosts, we should always use VMBUS_MESSAGE_CONNECTION_ID (1).
+ */
+ if (version >= VERSION_WIN10_V5) {
+ msg->msg_sint = VMBUS_MESSAGE_SINT;
+ vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID_4;
+ } else {
+ msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
+ vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID;
+ }
+
msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages[0]);
msg->monitor_page2 = virt_to_phys(vmbus_connection.monitor_pages[1]);
/*
@@ -137,6 +160,10 @@ static int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo,
/* Check if successful */
if (msginfo->response.version_response.version_supported) {
vmbus_connection.conn_state = CONNECTED;
+
+ if (version >= VERSION_WIN10_V5)
+ vmbus_connection.msg_conn_id =
+ msginfo->response.version_response.msg_conn_id;
} else {
return -ECONNREFUSED;
}
@@ -354,13 +381,14 @@ void vmbus_on_event(unsigned long data)
*/
int vmbus_post_msg(void *buffer, size_t buflen, bool can_sleep)
{
+ struct vmbus_channel_message_header *hdr;
union hv_connection_id conn_id;
int ret = 0;
int retries = 0;
u32 usec = 1;

conn_id.asu32 = 0;
- conn_id.u.id = VMBUS_MESSAGE_CONNECTION_ID;
+ conn_id.u.id = vmbus_connection.msg_conn_id;

/*
* hv_post_message() can have transient failures because of
@@ -372,6 +400,18 @@ int vmbus_post_msg(void *buffer, size_t buflen, bool can_sleep)

switch (ret) {
case HV_STATUS_INVALID_CONNECTION_ID:
+ /*
+ * See vmbus_negotiate_version(): VMBus protocol 5.0
+ * requires that we must use
+ * VMBUS_MESSAGE_CONNECTION_ID_4 for the Initiate
+ * Contact message, but on old hosts that only
+ * support VMBus protocol 4.0 or lower, here we get
+ * HV_STATUS_INVALID_CONNECTION_ID and we should
+ * return an error immediately without retrying.
+ */
+ hdr = (struct vmbus_channel_message_header *)buffer;
+ if (hdr->msgtype == CHANNELMSG_INITIATE_CONTACT)
+ return -EINVAL;
/*
* We could get this if we send messages too
* frequently.
diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
index f761bef36e77..72eaba3d50fc 100644
--- a/drivers/hv/hyperv_vmbus.h
+++ b/drivers/hv/hyperv_vmbus.h
@@ -187,6 +187,7 @@ struct hv_input_post_message {

enum {
VMBUS_MESSAGE_CONNECTION_ID = 1,
+ VMBUS_MESSAGE_CONNECTION_ID_4 = 4,
VMBUS_MESSAGE_PORT_ID = 1,
VMBUS_EVENT_CONNECTION_ID = 2,
VMBUS_EVENT_PORT_ID = 2,
@@ -302,6 +303,8 @@ struct vmbus_connection {
*/
int connect_cpu;

+ u32 msg_conn_id;
+
atomic_t offer_in_progress;

enum vmbus_connect_state conn_state;
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index 192ed8fbc403..11b5612dc066 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -163,6 +163,7 @@ static inline u32 hv_get_bytes_to_write(const struct hv_ring_buffer_info *rbi)
* 2 . 4 (Windows 8)
* 3 . 0 (Windows 8 R2)
* 4 . 0 (Windows 10)
+ * 5 . 0 (Newer Windows 10)
*/

#define VERSION_WS2008 ((0 << 16) | (13))
@@ -170,10 +171,11 @@ static inline u32 hv_get_bytes_to_write(const struct hv_ring_buffer_info *rbi)
#define VERSION_WIN8 ((2 << 16) | (4))
#define VERSION_WIN8_1 ((3 << 16) | (0))
#define VERSION_WIN10 ((4 << 16) | (0))
+#define VERSION_WIN10_V5 ((5 << 16) | (0))

#define VERSION_INVAL -1

-#define VERSION_CURRENT VERSION_WIN10
+#define VERSION_CURRENT VERSION_WIN10_V5

/* Make maximum size of pipe payload of 16K */
#define MAX_PIPE_DATA_PAYLOAD (sizeof(u8) * 16384)
@@ -570,7 +572,14 @@ struct vmbus_channel_initiate_contact {
struct vmbus_channel_message_header header;
u32 vmbus_version_requested;
u32 target_vcpu; /* The VCPU the host should respond to */
- u64 interrupt_page;
+ union {
+ u64 interrupt_page;
+ struct {
+ u8 msg_sint;
+ u8 padding1[3];
+ u32 padding2;
+ };
+ };
u64 monitor_page1;
u64 monitor_page2;
} __packed;
@@ -585,6 +594,19 @@ struct vmbus_channel_tl_connect_request {
struct vmbus_channel_version_response {
struct vmbus_channel_message_header header;
u8 version_supported;
+
+ u8 connection_state;
+ u16 padding;
+
+ /*
+ * On new hosts that support VMBus protocol 5.0, we must use
+ * VMBUS_MESSAGE_CONNECTION_ID_4 for the Initiate Contact Message,
+ * and for subsequent messages, we must use the Message Connection ID
+ * field in the host-returned Version Response Message.
+ *
+ * On old hosts, we should always use VMBUS_MESSAGE_CONNECTION_ID (1).
+ */
+ u32 msg_conn_id;
} __packed;

enum vmbus_channel_state {
--
2.15.1
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