[PATCH 10/11] vmci_route.patch: VMCI routing implementation.

[George Zhang]

Signed-off-by: George Zhang <georgezhang@xxxxxxxxxx>
---
 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..dc98564
--- /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 fromGuest,
+              enum vmci_route *route)
+{
+       bool hasHostDevice = vmci_host_code_active();
+       bool hasGuestDevice = vmci_guest_code_active();
+
+       ASSERT(src);
+       ASSERT(dst);
+       ASSERT(route);
+
+       *route = VMCI_ROUTE_NONE;
+
+       /*
+        * "fromGuest" 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 (fromGuest)
+                       return VMCI_ERROR_DST_UNREACHABLE;
+
+               /*
+                * We must be acting as a guest in order to send to
+                * the hypervisor.
+                */
+               if (!hasGuestDevice)
+                       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 (hasHostDevice) {
+                               *route = VMCI_ROUTE_AS_HOST;
+                               return VMCI_SUCCESS;
+                       } else {
+                               return VMCI_ERROR_DEVICE_NOT_FOUND;
+                       }
+               }
+
+               if (!fromGuest && hasGuestDevice) {
+                       /* 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 (!hasHostDevice)
+                       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 (fromGuest)
+                               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 (hasHostDevice) {
+               /* 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 (fromGuest)
+                                       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 (!hasGuestDevice) {
+                       /*
+                        * 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 (!hasGuestDevice) {
+               /*
+                * 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..a62cf9b
--- /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 fromGuest, enum vmci_route *route);
+
+#endif /* _VMCI_ROUTE_H_ */

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