qemu-patch-raspberry4/hw/xen/xen-bus-helper.c
Paul Durrant 82a29e3048 xen: add xenstore watcher infrastructure
A Xen PV frontend communicates its state to the PV backend by writing to
the 'state' key in the frontend area in xenstore. It is therefore
necessary for a XenDevice implementation to be notified whenever the
value of this key changes.

This patch adds code to do this as follows:

- an 'fd handler' is registered on the libxenstore handle which will be
  triggered whenever a 'watch' event occurs
- primitives are added to xen-bus-helper to add or remove watch events
- a list of Notifier objects is added to XenBus to provide a mechanism
  to call the appropriate 'watch handler' when its associated event
  occurs

The xen-block implementation is extended with a 'frontend_changed' method,
which calls as-yet stub 'connect' and 'disconnect' functions when the
relevant frontend state transitions occur. A subsequent patch will supply
a full implementation for these functions.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Anthony Perard <anthony.perard@citrix.com>
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
2019-01-14 13:45:40 +00:00

185 lines
4.6 KiB
C

/*
* Copyright (c) 2018 Citrix Systems Inc.
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*/
#include "qemu/osdep.h"
#include "hw/hw.h"
#include "hw/sysbus.h"
#include "hw/xen/xen.h"
#include "hw/xen/xen-bus.h"
#include "hw/xen/xen-bus-helper.h"
#include "qapi/error.h"
#include <glib/gprintf.h>
struct xs_state {
enum xenbus_state statenum;
const char *statestr;
};
#define XS_STATE(state) { state, #state }
static struct xs_state xs_state[] = {
XS_STATE(XenbusStateUnknown),
XS_STATE(XenbusStateInitialising),
XS_STATE(XenbusStateInitWait),
XS_STATE(XenbusStateInitialised),
XS_STATE(XenbusStateConnected),
XS_STATE(XenbusStateClosing),
XS_STATE(XenbusStateClosed),
XS_STATE(XenbusStateReconfiguring),
XS_STATE(XenbusStateReconfigured),
};
#undef XS_STATE
const char *xs_strstate(enum xenbus_state state)
{
unsigned int i;
for (i = 0; i < ARRAY_SIZE(xs_state); i++) {
if (xs_state[i].statenum == state) {
return xs_state[i].statestr;
}
}
return "INVALID";
}
void xs_node_create(struct xs_handle *xsh, xs_transaction_t tid,
const char *node, struct xs_permissions perms[],
unsigned int nr_perms, Error **errp)
{
trace_xs_node_create(node);
if (!xs_write(xsh, tid, node, "", 0)) {
error_setg_errno(errp, errno, "failed to create node '%s'", node);
return;
}
if (!xs_set_permissions(xsh, tid, node, perms, nr_perms)) {
error_setg_errno(errp, errno, "failed to set node '%s' permissions",
node);
}
}
void xs_node_destroy(struct xs_handle *xsh, xs_transaction_t tid,
const char *node, Error **errp)
{
trace_xs_node_destroy(node);
if (!xs_rm(xsh, tid, node)) {
error_setg_errno(errp, errno, "failed to destroy node '%s'", node);
}
}
void xs_node_vprintf(struct xs_handle *xsh, xs_transaction_t tid,
const char *node, const char *key, Error **errp,
const char *fmt, va_list ap)
{
char *path, *value;
int len;
path = (strlen(node) != 0) ? g_strdup_printf("%s/%s", node, key) :
g_strdup(key);
len = g_vasprintf(&value, fmt, ap);
trace_xs_node_vprintf(path, value);
if (!xs_write(xsh, tid, path, value, len)) {
error_setg_errno(errp, errno, "failed to write '%s' to '%s'",
value, path);
}
g_free(value);
g_free(path);
}
void xs_node_printf(struct xs_handle *xsh, xs_transaction_t tid,
const char *node, const char *key, Error **errp,
const char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
xs_node_vprintf(xsh, tid, node, key, errp, fmt, ap);
va_end(ap);
}
int xs_node_vscanf(struct xs_handle *xsh, xs_transaction_t tid,
const char *node, const char *key, Error **errp,
const char *fmt, va_list ap)
{
char *path, *value;
int rc;
path = (strlen(node) != 0) ? g_strdup_printf("%s/%s", node, key) :
g_strdup(key);
value = xs_read(xsh, tid, path, NULL);
trace_xs_node_vscanf(path, value);
if (value) {
rc = vsscanf(value, fmt, ap);
} else {
error_setg_errno(errp, errno, "failed to read from '%s'",
path);
rc = EOF;
}
free(value);
g_free(path);
return rc;
}
int xs_node_scanf(struct xs_handle *xsh, xs_transaction_t tid,
const char *node, const char *key, Error **errp,
const char *fmt, ...)
{
va_list ap;
int rc;
va_start(ap, fmt);
rc = xs_node_vscanf(xsh, tid, node, key, errp, fmt, ap);
va_end(ap);
return rc;
}
void xs_node_watch(struct xs_handle *xsh, const char *node, const char *key,
char *token, Error **errp)
{
char *path;
path = (strlen(node) != 0) ? g_strdup_printf("%s/%s", node, key) :
g_strdup(key);
trace_xs_node_watch(path);
if (!xs_watch(xsh, path, token)) {
error_setg_errno(errp, errno, "failed to watch node '%s'", path);
}
g_free(path);
}
void xs_node_unwatch(struct xs_handle *xsh, const char *node,
const char *key, const char *token, Error **errp)
{
char *path;
path = (strlen(node) != 0) ? g_strdup_printf("%s/%s", node, key) :
g_strdup(key);
trace_xs_node_unwatch(path);
if (!xs_unwatch(xsh, path, token)) {
error_setg_errno(errp, errno, "failed to unwatch node '%s'", path);
}
g_free(path);
}