VMCI: routing implementation.

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>
Acked-by: Andy king <acking@vmware.com>
Acked-by: Dmitry Torokhov <dtor@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2 files changed, 256 insertions, 0 deletions

diff --git a/drivers/misc/vmw_vmci/vmci_route.c b/drivers/misc/vmw_vmci/vmci_route.c
new file mode 100644
index 000000000000..91090658b929
--- /dev/null
+++ b/drivers/misc/vmw_vmci/vmci_route.c
@@ -0,0 +1,226 @@
+/*
+ * 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_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();
+
+        *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.
+                                 */
+
+                                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.
+                 */
+                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 000000000000..3b30e82419c3
--- /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_ */