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* An implementation of HyperV key value pair (KVP) functionality for Linux.
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* Copyright (C) 2010, Novell, Inc.
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* Author : K. Y. Srinivasan <ksrinivasan@novell.com>
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 as published
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* by the Free Software Foundation.
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
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* NON INFRINGEMENT. See the GNU General Public License for more
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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* Maximum value size - used for both key names and value data, and includes
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* any applicable NULL terminators.
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* Note: This limit is somewhat arbitrary, but falls easily within what is
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* supported for all native guests (back to Win 2000) and what is reasonable
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* for the IC KVP exchange functionality. Note that Windows Me/98/95 are
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* limited to 255 character key names.
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* MSDN recommends not storing data values larger than 2048 bytes in the
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* Note: This value is used in defining the KVP exchange message - this value
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* cannot be modified without affecting the message size and compatibility.
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* bytes, including any null terminators
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#define HV_KVP_EXCHANGE_MAX_VALUE_SIZE (2048)
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* Maximum key size - the registry limit for the length of an entry name
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* is 256 characters, including the null terminator
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#define HV_KVP_EXCHANGE_MAX_KEY_SIZE (512)
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* In Linux, we implement the KVP functionality in two components:
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* 1) The kernel component which is packaged as part of the hv_utils driver
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* is responsible for communicating with the host and responsible for
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* implementing the host/guest protocol. 2) A user level daemon that is
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* responsible for data gathering.
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* Host/Guest Protocol: The host iterates over an index and expects the guest
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* to assign a key name to the index and also return the value corresponding to
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* the key. The host will have atmost one KVP transaction outstanding at any
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* given point in time. The host side iteration stops when the guest returns
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* an error. Microsoft has specified the following mapping of key names to
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* host specified index:
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* 0 FullyQualifiedDomainName
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* 1 IntegrationServicesVersion
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* 2 NetworkAddressIPv4
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* 3 NetworkAddressIPv6
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* 9 ProcessorArchitecture
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* The Windows host expects the Key Name and Key Value to be encoded in utf16.
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* Guest Kernel/KVP Daemon Protocol: As noted earlier, we implement all of the
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* data gathering functionality in a user mode daemon. The user level daemon
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* is also responsible for binding the key name to the index as well. The
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* kernel and user-level daemon communicate using a connector channel.
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* The user mode component first registers with the
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* the kernel component. Subsequently, the kernel component requests, data
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* for the specified keys. In response to this message the user mode component
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* fills in the value corresponding to the specified key. We overload the
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* sequence field in the cn_msg header to define our KVP message types.
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* The kernel component simply acts as a conduit for communication between the
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* Windows host and the user-level daemon. The kernel component passes up the
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* index received from the Host to the user-level daemon. If the index is
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* valid (supported), the corresponding key as well as its
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* value (both are strings) is returned. If the index is invalid
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* (not supported), a NULL key string is returned.
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* The following definitions are shared with the user-mode component; do not
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* change any of this without making the corresponding changes in
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* the KVP user-mode component.
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#define CN_KVP_VAL 0x1 /* This supports queries from the kernel */
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#define CN_KVP_USER_VAL 0x2 /* This supports queries from the user */
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KVP_REGISTER = 0, /* Register the user mode component */
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KVP_KERNEL_GET, /* Kernel is requesting the value */
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KVP_KERNEL_SET, /* Kernel is providing the value */
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KVP_USER_GET, /* User is requesting the value */
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KVP_USER_SET /* User is providing the value */
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__u32 kvp_index; /* Key index */
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__u8 kvp_key[HV_KVP_EXCHANGE_MAX_KEY_SIZE]; /* Key name */
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__u8 kvp_value[HV_KVP_EXCHANGE_MAX_VALUE_SIZE]; /* Key value */
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* Registry value types.
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enum hv_kvp_exchg_op {
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KVP_OP_COUNT /* Number of operations, must be last. */
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enum hv_kvp_exchg_pool {
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KVP_POOL_EXTERNAL = 0,
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KVP_POOL_AUTO_EXTERNAL,
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KVP_POOL_AUTO_INTERNAL,
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KVP_POOL_COUNT /* Number of pools, must be last. */
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struct hv_kvp_exchg_msg_value {
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u8 key[HV_KVP_EXCHANGE_MAX_KEY_SIZE];
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u8 value[HV_KVP_EXCHANGE_MAX_VALUE_SIZE];
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struct hv_kvp_msg_enumerate {
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struct hv_kvp_exchg_msg_value data;
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struct hv_kvp_hdr kvp_hdr;
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struct hv_kvp_msg_enumerate kvp_data;
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int hv_kvp_init(struct hv_util_service *);
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void hv_kvp_deinit(void);
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void hv_kvp_onchannelcallback(void *);
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#endif /* __KERNEL__ */