vmbus: vmbus implementation

Add the VMBus infrastructure -- bus, devices, root bridge, vmbus state
machine, vmbus channel interactions, etc.

VMBus is a collection of technologies.  At its lowest layer, it's a message
passing and signaling mechanism, allowing efficient passing of messages to and
from guest VMs.  A layer higher, it's a mechanism for defining channels of
communication, where each channel is tagged with a type (which implies a
protocol) and a instance ID.  A layer higher than that, it's a bus driver,
serving as the basis of device enumeration within a VM, where a channel can
optionally be exposed as a paravirtual device.  When a server-side (paravirtual
back-end) component wishes to offer a channel to a guest VM, it does so by
specifying a channel type, a mode, and an instance ID.  VMBus then exposes this
in the guest.

More information about VMBus can be found in the file
vmbuskernelmodeclientlibapi.h in Microsoft's WDK.

TODO:
 - split into smaller palatable pieces
 - more comments
 - check and handle corner cases

Kudos to Evgeny Yakovlev (formerly eyakovlev@virtuozzo.com) and Andrey
Smetatin (formerly asmetanin@virtuozzo.com) for research and
prototyping.

Signed-off-by: Roman Kagan <rkagan@virtuozzo.com>
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Signed-off-by: Jon Doron <arilou@gmail.com>
Message-Id: <20200424123444.3481728-4-arilou@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 32 insertions, 0 deletions

diff --git a/include/hw/hyperv/vmbus-bridge.h b/include/hw/hyperv/vmbus-bridge.h
new file mode 100644
index 0000000..9cc8f78
--- /dev/null
+++ b/include/hw/hyperv/vmbus-bridge.h
@@ -0,0 +1,32 @@
+/*
+ * QEMU Hyper-V VMBus root bridge
+ *
+ * Copyright (c) 2017-2018 Virtuozzo International GmbH.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#ifndef HW_HYPERV_VMBUS_BRIDGE_H
+#define HW_HYPERV_VMBUS_BRIDGE_H
+
+#include "hw/sysbus.h"
+
+#define TYPE_VMBUS_BRIDGE "vmbus-bridge"
+
+typedef struct VMBus VMBus;
+
+typedef struct VMBusBridge {
+    SysBusDevice parent_obj;
+
+    VMBus *bus;
+} VMBusBridge;
+
+#define VMBUS_BRIDGE(obj) OBJECT_CHECK(VMBusBridge, (obj), TYPE_VMBUS_BRIDGE)
+
+static inline VMBusBridge *vmbus_bridge_find(void)
+{
+    return VMBUS_BRIDGE(object_resolve_path_type("", TYPE_VMBUS_BRIDGE, NULL));
+}
+
+#endif