freebsd-skq/usr.sbin/bhyve/config.h
John Baldwin 621b509048 Refactor configuration management in bhyve.
Replace the existing ad-hoc configuration via various global variables
with a small database of key-value pairs.  The database supports
heirarchical keys using a MIB-like syntax to name the path to a given
key.  Values are always stored as strings.  The API used to manage
configuation values does include wrappers to handling boolean values.
Other values use non-string types require parsing by consumers.

The configuration values are stored in a tree using nvlists.  Leaf
nodes hold string values.  Configuration values are permitted to
reference other configuration values using '%(name)'.  This permits
constructing template configurations.

All existing command line arguments now set configuration values.  For
devices, the "-s" option parses its option argument to generate a list
of key-value pairs for the given device.

A new '-o' command line option permits setting an individual
configuration variable.  The key name is always given as a full path
of dot-separated components.

A new '-k' command line option parses a simple configuration file.
This configuration file holds a flat list of 'key=value' lines where
the 'key' is the full path of a configuration variable.  Lines
starting with a '#' are comments.

In general, bhyve starts by parsing command line options in sequence
and applying those settings to configuration values.  Once this is
complete, bhyve then begins initializing its state based on the
configuration values.  This means that subsequent configuration
options or files may override or supplement previously given settings.

A special 'config.dump' configuration value can be set to true to help
debug configuration issues.  When this value is set, bhyve will print
out the configuration variables as a flat list of 'key=value' lines.

Most command line argments map to a single configuration variable,
e.g.  '-w' sets the 'x86.strictmsr' value to false.  A few command
line arguments have less obvious effects:

- Multiple '-p' options append their values (as a comma-seperated
  list) to "vcpu.N.cpuset" values (where N is a decimal vcpu number).

- For '-s' options, a pci.<bus>.<slot>.<function> node is created.
  The first argument to '-s' (the device type) is used as the value of
  a "device" variable.  Additional comma-separated arguments are then
  parsed into 'key=value' pairs and used to set additional variables
  under the device node.  A PCI device emulation driver can provide
  its own hook to override the parsing of the additonal '-s' arguments
  after the device type.

  After the configuration phase as completed, the init_pci hook
  then walks the "pci.<bus>.<slot>.<func>" nodes.  It uses the
  "device" value to find the device model to use.  The device
  model's init routine is passed a reference to its nvlist node
  in the configuration tree which it can query for specific
  variables.

  The result is that a lot of the string parsing is removed from
  the device models and centralized.  In addition, adding a new
  variable just requires teaching the model to look for the new
  variable.

- For '-l' options, a similar model is used where the string is
  parsed into values that are later read during initialization.
  One key note here is that the serial ports use the commonly
  used lowercase names from existing documentation and examples
  (e.g. "lpc.com1") instead of the uppercase names previously
  used internally in bhyve.

Reviewed by:	grehan
MFC after:	3 months
Differential Revision:	https://reviews.freebsd.org/D26035
2021-03-18 16:30:26 -07:00

120 lines
4.3 KiB
C

/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* Copyright (c) 2021 John H. Baldwin <jhb@FreeBSD.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $FreeBSD$
*/
#ifndef __CONFIG_H__
#define __CONFIG_H__
#include <sys/nv.h>
/*-
* Manages a configuration database backed by an nv(9) list.
*
* The database only stores string values. Callers should parse
* values into other types if needed. String values can reference
* other configuration variables using a '%(name)' syntax. In this
* case, the name must be the the full path of the configuration
* variable. The % character can be escaped with a preceding \ to
* avoid expansion. Any \ characters must be escaped.
*
* Configuration variables are stored in a tree. The full path of a
* variable is specified as a dot-separated name similar to sysctl(8)
* OIDs.
*/
/*
* Fetches the value of a configuration variable. If the "raw" value
* contains references to other configuration variables, this function
* expands those references and returns a pointer to the parsed
* string. The string's storage is only stable until the next call to
* this function.
*
* If no node is found, returns NULL.
*
* If 'parent' is NULL, 'name' is assumed to be a top-level variable.
*/
const char *get_config_value_node(const nvlist_t *parent, const char *name);
/*
* Similar to get_config_value_node but expects a full path to the
* leaf node.
*/
const char *get_config_value(const char *path);
/* Initializes the tree to an empty state. */
void init_config(void);
/*
* Creates an existing configuration node via a dot-separated OID
* path. Will fail if the path names an existing leaf configuration
* variable. If the node already exists, this returns a pointer to
* the existing node.
*/
nvlist_t *create_config_node(const char *path);
/*
* Looks for an existing configuration node via a dot-separated OID
* path. Will fail if the path names an existing leaf configuration
* variable.
*/
nvlist_t *find_config_node(const char *path);
/*
* Similar to the above, but treats the path relative to an existing
* 'parent' node rather than as an absolute path.
*/
nvlist_t *create_relative_config_node(nvlist_t *parent, const char *path);
nvlist_t *find_relative_config_node(nvlist_t *parent, const char *path);
/*
* Adds or replaces the value of the specified variable.
*
* If 'parent' is NULL, 'name' is assumed to be a top-level variable.
*/
void set_config_value_node(nvlist_t *parent, const char *name,
const char *value);
/*
* Similar to set_config_value_node but expects a full path to the
* leaf node.
*/
void set_config_value(const char *path, const char *value);
/* Convenience wrappers for boolean variables. */
bool get_config_bool(const char *path);
bool get_config_bool_node(const nvlist_t *parent, const char *name);
bool get_config_bool_default(const char *path, bool def);
bool get_config_bool_node_default(const nvlist_t *parent, const char *name,
bool def);
void set_config_bool(const char *path, bool value);
void set_config_bool_node(nvlist_t *parent, const char *name, bool value);
void dump_config(void);
#endif /* !__CONFIG_H__ */