[PATCH 09/10] VMCI: routing implementation.

George Zhang
2012-10-16T00:29:50Z

VMCI routing code is responsible for routing between various hosts/guests
as well as routing in nested scenarios.

Signed-off-by: George Zhang <georgezhang@vmware.com>
---
drivers/misc/vmw_vmci/vmci_route.c | 237 ++++++++++++++++++++++++++++++++++++
drivers/misc/vmw_vmci/vmci_route.h | 30 +++++
2 files changed, 267 insertions(+), 0 deletions(-)
create mode 100644 drivers/misc/vmw_vmci/vmci_route.c
create mode 100644 drivers/misc/vmw_vmci/vmci_route.h

diff --git a/drivers/misc/vmw_vmci/vmci_route.c b/drivers/misc/vmw_vmci/vmci_route.c
new file mode 100644
index 0000000..8aa43ee
--- /dev/null
+++ b/drivers/misc/vmw_vmci/vmci_route.c
@@ -0,0 +1,237 @@
+/*
+ * VMware VMCI Driver
+ *
+ * Copyright (C) 2012 VMware, Inc. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation version 2 and no later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * for more details.
+ */
+
+#include <linux/vmw_vmci_defs.h>
+#include <linux/vmw_vmci_api.h>
+
+#include "vmci_common_int.h"
+#include "vmci_context.h"
+#include "vmci_driver.h"
+#include "vmci_route.h"
+
+/*
+ * Make a routing decision for the given source and destination handles.
+ * This will try to determine the route using the handles and the available
+ * devices. Will set the source context if it is invalid.
+ */
+int vmci_route(struct vmci_handle *src,
+ const struct vmci_handle *dst,
+ bool from_guest,
+ enum vmci_route *route)
+{
+ bool has_host_device = vmci_host_code_active();
+ bool has_guest_device = vmci_guest_code_active();
+
+ ASSERT(src);
+ ASSERT(dst);
+ ASSERT(route);
+
+ *route = VMCI_ROUTE_NONE;
+
+ /*
+ * "from_guest" is only ever set to true by
+ * IOCTL_VMCI_DATAGRAM_SEND (or by the vmkernel equivalent),
+ * which comes from the VMX, so we know it is coming from a
+ * guest.
+ *
+ * To avoid inconsistencies, test these once. We will test
+ * them again when we do the actual send to ensure that we do
+ * not touch a non-existent device.
+ */
+
+ /* Must have a valid destination context. */
+ if (VMCI_INVALID_ID == dst->context)
+ return VMCI_ERROR_INVALID_ARGS;
+
+ /* Anywhere to hypervisor. */
+ if (VMCI_HYPERVISOR_CONTEXT_ID == dst->context) {
+
+ /*
+ * If this message already came from a guest then we
+ * cannot send it to the hypervisor. It must come
+ * from a local client.
+ */
+ if (from_guest)
+ return VMCI_ERROR_DST_UNREACHABLE;
+
+ /*
+ * We must be acting as a guest in order to send to
+ * the hypervisor.
+ */
+ if (!has_guest_device)
+ return VMCI_ERROR_DEVICE_NOT_FOUND;
+
+ /* And we cannot send if the source is the host context. */
+ if (VMCI_HOST_CONTEXT_ID == src->context)
+ return VMCI_ERROR_INVALID_ARGS;
+
+ /*
+ * If the client passed the ANON source handle then
+ * respect it (both context and resource are invalid).
+ * However, if they passed only an invalid context,
+ * then they probably mean ANY, in which case we
+ * should set the real context here before passing it
+ * down.
+ */
+ if (VMCI_INVALID_ID == src->context &&
+ VMCI_INVALID_ID != src->resource)
+ src->context = vmci_get_context_id();
+
+ /* Send from local client down to the hypervisor. */
+ *route = VMCI_ROUTE_AS_GUEST;
+ return VMCI_SUCCESS;
+ }
+
+ /* Anywhere to local client on host. */
+ if (VMCI_HOST_CONTEXT_ID == dst->context) {
+ /*
+ * If it is not from a guest but we are acting as a
+ * guest, then we need to send it down to the host.
+ * Note that if we are also acting as a host then this
+ * will prevent us from sending from local client to
+ * local client, but we accept that restriction as a
+ * way to remove any ambiguity from the host context.
+ */
+ if (src->context == VMCI_HYPERVISOR_CONTEXT_ID) {
+ /*
+ * If the hypervisor is the source, this is
+ * host local communication. The hypervisor
+ * may send vmci event datagrams to the host
+ * itself, but it will never send datagrams to
+ * an "outer host" through the guest device.
+ */
+
+ if (has_host_device) {
+ *route = VMCI_ROUTE_AS_HOST;
+ return VMCI_SUCCESS;
+ } else {
+ return VMCI_ERROR_DEVICE_NOT_FOUND;
+ }
+ }
+
+ if (!from_guest && has_guest_device) {
+ /* If no source context then use the current. */
+ if (VMCI_INVALID_ID == src->context)
+ src->context = vmci_get_context_id();
+
+ /* Send it from local client down to the host. */
+ *route = VMCI_ROUTE_AS_GUEST;
+ return VMCI_SUCCESS;
+ }
+
+ /*
+ * Otherwise we already received it from a guest and
+ * it is destined for a local client on this host, or
+ * it is from another local client on this host. We
+ * must be acting as a host to service it.
+ */
+ if (!has_host_device)
+ return VMCI_ERROR_DEVICE_NOT_FOUND;
+
+ if (VMCI_INVALID_ID == src->context) {
+ /*
+ * If it came from a guest then it must have a
+ * valid context. Otherwise we can use the
+ * host context.
+ */
+ if (from_guest)
+ return VMCI_ERROR_INVALID_ARGS;
+
+ src->context = VMCI_HOST_CONTEXT_ID;
+ }
+
+ /* Route to local client. */
+ *route = VMCI_ROUTE_AS_HOST;
+ return VMCI_SUCCESS;
+ }
+
+ /*
+ * If we are acting as a host then this might be destined for
+ * a guest.
+ */
+ if (has_host_device) {
+ /* It will have a context if it is meant for a guest. */
+ if (vmci_ctx_exists(dst->context)) {
+ if (VMCI_INVALID_ID == src->context) {
+ /*
+ * If it came from a guest then it
+ * must have a valid context.
+ * Otherwise we can use the host
+ * context.
+ */
+
+ if (from_guest)
+ return VMCI_ERROR_INVALID_ARGS;
+
+ src->context = VMCI_HOST_CONTEXT_ID;
+ } else if (VMCI_CONTEXT_IS_VM(src->context) &&
+ src->context != dst->context) {
+ /*
+ * VM to VM communication is not
+ * allowed. Since we catch all
+ * communication destined for the host
+ * above, this must be destined for a
+ * VM since there is a valid context.
+ */
+
+ ASSERT(VMCI_CONTEXT_IS_VM(dst->context));
+
+ return VMCI_ERROR_DST_UNREACHABLE;
+ }
+
+ /* Pass it up to the guest. */
+ *route = VMCI_ROUTE_AS_HOST;
+ return VMCI_SUCCESS;
+ } else if (!has_guest_device) {
+ /*
+ * The host is attempting to reach a CID
+ * without an active context, and we can't
+ * send it down, since we have no guest
+ * device.
+ */
+
+ return VMCI_ERROR_DST_UNREACHABLE;
+ }
+ }
+
+ /*
+ * We must be a guest trying to send to another guest, which means
+ * we need to send it down to the host. We do not filter out VM to
+ * VM communication here, since we want to be able to use the guest
+ * driver on older versions that do support VM to VM communication.
+ */
+ if (!has_guest_device) {
+ /*
+ * Ending up here means we have neither guest nor host
+ * device. That shouldn't happen, since any VMCI
+ * client in the kernel should have done a successful
+ * VMCI_DeviceGet.
+ */
+
+ ASSERT(false);
+ return VMCI_ERROR_DEVICE_NOT_FOUND;
+ }
+
+ /* If no source context then use the current context. */
+ if (VMCI_INVALID_ID == src->context)
+ src->context = vmci_get_context_id();
+
+ /*
+ * Send it from local client down to the host, which will
+ * route it to the other guest for us.
+ */
+ *route = VMCI_ROUTE_AS_GUEST;
+ return VMCI_SUCCESS;
+}
diff --git a/drivers/misc/vmw_vmci/vmci_route.h b/drivers/misc/vmw_vmci/vmci_route.h
new file mode 100644
index 0000000..3b30e82
--- /dev/null
+++ b/drivers/misc/vmw_vmci/vmci_route.h
@@ -0,0 +1,30 @@
+/*
+ * VMware VMCI Driver
+ *
+ * Copyright (C) 2012 VMware, Inc. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation version 2 and no later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * for more details.
+ */
+
+#ifndef _VMCI_ROUTE_H_
+#define _VMCI_ROUTE_H_
+
+#include <linux/vmw_vmci_defs.h>
+
+enum vmci_route {
+ VMCI_ROUTE_NONE,
+ VMCI_ROUTE_AS_HOST,
+ VMCI_ROUTE_AS_GUEST,
+};
+
+int vmci_route(struct vmci_handle *src, const struct vmci_handle *dst,
+ bool from_guest, enum vmci_route *route);
+
+#endif /* _VMCI_ROUTE_H_ */