um: virtio: Implement VHOST_USER_PROTOCOL_F_SLAVE_REQ

Implement the communication channel for the device to notify
us of some events, and notably implement the handling of the
config updates needed for the combination of this feature
and VHOST_USER_PROTOCOL_F_CONFIG.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

1 files changed, 15 insertions, 3 deletions

diff --git a/arch/um/drivers/vhost_user.h b/arch/um/drivers/vhost_user.h
index 2a9829b0782b..8aee9919581e 100644
--- a/arch/um/drivers/vhost_user.h
+++ b/arch/um/drivers/vhost_user.h
@@ -9,7 +9,8 @@
 /* Feature bits */
 #define VHOST_USER_F_PROTOCOL_FEATURES	30
 /* Protocol feature bits */
-#define VHOST_USER_PROTOCOL_F_CONFIG	9
+#define VHOST_USER_PROTOCOL_F_SLAVE_REQ		5
+#define VHOST_USER_PROTOCOL_F_CONFIG		9
 /* Vring state index masks */
 #define VHOST_USER_VRING_INDEX_MASK	0xff
 #define VHOST_USER_VRING_POLL_MASK	BIT(8)
@@ -19,7 +20,8 @@
 /* Supported transport features */
 #define VHOST_USER_SUPPORTED_F		BIT_ULL(VHOST_USER_F_PROTOCOL_FEATURES)
 /* Supported protocol features */
-#define VHOST_USER_SUPPORTED_PROTOCOL_F	BIT_ULL(VHOST_USER_PROTOCOL_F_CONFIG)
+#define VHOST_USER_SUPPORTED_PROTOCOL_F	(BIT_ULL(VHOST_USER_PROTOCOL_F_SLAVE_REQ) | \
+					 BIT_ULL(VHOST_USER_PROTOCOL_F_CONFIG))
 
 enum vhost_user_request {
 	VHOST_USER_GET_FEATURES = 1,
@@ -49,8 +51,18 @@ enum vhost_user_request {
 	VHOST_USER_SET_CONFIG = 25,
 };
 
+enum vhost_user_slave_request {
+	VHOST_USER_SLAVE_IOTLB_MSG = 1,
+	VHOST_USER_SLAVE_CONFIG_CHANGE_MSG = 2,
+	VHOST_USER_SLAVE_VRING_HOST_NOTIFIER_MSG = 3,
+};
+
 struct vhost_user_header {
-	u32 request; /* Use enum vhost_user_request */
+	/*
+	 * Use enum vhost_user_request for outgoing messages,
+	 * uses enum vhost_user_slave_request for incoming ones.
+	 */
+	u32 request;
 	u32 flags;
 	u32 size;
 } __packed;