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qemu/hw/i386/kvm/xen_xenstore.c
Stefan Hajnoczi 195801d700 system/cpus: rename qemu_mutex_lock_iothread() to bql_lock() 
The Big QEMU Lock (BQL) has many names and they are confusing. The
actual QemuMutex variable is called qemu_global_mutex but it's commonly
referred to as the BQL in discussions and some code comments. The
locking APIs, however, are called qemu_mutex_lock_iothread() and
qemu_mutex_unlock_iothread().

The "iothread" name is historic and comes from when the main thread was
split into into KVM vcpu threads and the "iothread" (now called the main
loop thread). I have contributed to the confusion myself by introducing
a separate --object iothread, a separate concept unrelated to the BQL.

The "iothread" name is no longer appropriate for the BQL. Rename the
locking APIs to:
- void bql_lock(void)
- void bql_unlock(void)
- bool bql_locked(void)

There are more APIs with "iothread" in their names. Subsequent patches
will rename them. There are also comments and documentation that will be
updated in later patches.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Paul Durrant <paul@xen.org>
Acked-by: Fabiano Rosas <farosas@suse.de>
Acked-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Acked-by: Peter Xu <peterx@redhat.com>
Acked-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
Acked-by: Hyman Huang <yong.huang@smartx.com>
Reviewed-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Message-id: 20240102153529.486531-2-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2024-01-08 10:45:43 -05:00

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/*
* QEMU Xen emulation: Shared/overlay pages support
*
* Copyright © 2022 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Authors: David Woodhouse <dwmw2@infradead.org>
*
* 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 "qemu/host-utils.h"
#include "qemu/module.h"
#include "qemu/main-loop.h"
#include "qemu/cutils.h"
#include "qemu/error-report.h"
#include "qapi/error.h"
#include "qom/object.h"
#include "migration/vmstate.h"
#include "hw/sysbus.h"
#include "hw/xen/xen.h"
#include "hw/xen/xen_backend_ops.h"
#include "xen_overlay.h"
#include "xen_evtchn.h"
#include "xen_primary_console.h"
#include "xen_xenstore.h"
#include "sysemu/kvm.h"
#include "sysemu/kvm_xen.h"
#include "trace.h"
#include "xenstore_impl.h"
#include "hw/xen/interface/io/xs_wire.h"
#include "hw/xen/interface/event_channel.h"
#include "hw/xen/interface/grant_table.h"
#define TYPE_XEN_XENSTORE "xen-xenstore"
OBJECT_DECLARE_SIMPLE_TYPE(XenXenstoreState, XEN_XENSTORE)
#define ENTRIES_PER_FRAME_V1 (XEN_PAGE_SIZE / sizeof(grant_entry_v1_t))
#define ENTRIES_PER_FRAME_V2 (XEN_PAGE_SIZE / sizeof(grant_entry_v2_t))
#define XENSTORE_HEADER_SIZE ((unsigned int)sizeof(struct xsd_sockmsg))
struct XenXenstoreState {
/*< private >*/
SysBusDevice busdev;
/*< public >*/
XenstoreImplState *impl;
GList *watch_events; /* for the guest */
MemoryRegion xenstore_page;
struct xenstore_domain_interface *xs;
uint8_t req_data[XENSTORE_HEADER_SIZE + XENSTORE_PAYLOAD_MAX];
uint8_t rsp_data[XENSTORE_HEADER_SIZE + XENSTORE_PAYLOAD_MAX];
uint32_t req_offset;
uint32_t rsp_offset;
bool rsp_pending;
bool fatal_error;
evtchn_port_t guest_port;
evtchn_port_t be_port;
struct xenevtchn_handle *eh;
uint8_t *impl_state;
uint32_t impl_state_size;
struct xengntdev_handle *gt;
void *granted_xs;
};
struct XenXenstoreState *xen_xenstore_singleton;
static void xen_xenstore_event(void *opaque);
static void fire_watch_cb(void *opaque, const char *path, const char *token);
static struct xenstore_backend_ops emu_xenstore_backend_ops;
static void G_GNUC_PRINTF (4, 5) relpath_printf(XenXenstoreState *s,
GList *perms,
const char *relpath,
const char *fmt, ...)
{
gchar *abspath;
gchar *value;
va_list args;
GByteArray *data;
int err;
abspath = g_strdup_printf("/local/domain/%u/%s", xen_domid, relpath);
va_start(args, fmt);
value = g_strdup_vprintf(fmt, args);
va_end(args);
data = g_byte_array_new_take((void *)value, strlen(value));
err = xs_impl_write(s->impl, DOMID_QEMU, XBT_NULL, abspath, data);
assert(!err);
g_byte_array_unref(data);
err = xs_impl_set_perms(s->impl, DOMID_QEMU, XBT_NULL, abspath, perms);
assert(!err);
g_free(abspath);
}
static void xen_xenstore_realize(DeviceState *dev, Error **errp)
{
XenXenstoreState *s = XEN_XENSTORE(dev);
GList *perms;
if (xen_mode != XEN_EMULATE) {
error_setg(errp, "Xen xenstore support is for Xen emulation");
return;
}
memory_region_init_ram(&s->xenstore_page, OBJECT(dev), "xen:xenstore_page",
XEN_PAGE_SIZE, &error_abort);
memory_region_set_enabled(&s->xenstore_page, true);
s->xs = memory_region_get_ram_ptr(&s->xenstore_page);
memset(s->xs, 0, XEN_PAGE_SIZE);
/* We can't map it this early as KVM isn't ready */
xen_xenstore_singleton = s;
s->eh = xen_be_evtchn_open();
if (!s->eh) {
error_setg(errp, "Xenstore evtchn port init failed");
return;
}
aio_set_fd_handler(qemu_get_aio_context(), xen_be_evtchn_fd(s->eh),
xen_xenstore_event, NULL, NULL, NULL, s);
s->impl = xs_impl_create(xen_domid);
/* Populate the default nodes */
/* Nodes owned by 'dom0' but readable by the guest */
perms = g_list_append(NULL, xs_perm_as_string(XS_PERM_NONE, DOMID_QEMU));
perms = g_list_append(perms, xs_perm_as_string(XS_PERM_READ, xen_domid));
relpath_printf(s, perms, "", "%s", "");
relpath_printf(s, perms, "domid", "%u", xen_domid);
relpath_printf(s, perms, "control/platform-feature-xs_reset_watches", "%u", 1);
relpath_printf(s, perms, "control/platform-feature-multiprocessor-suspend", "%u", 1);
relpath_printf(s, perms, "platform/acpi", "%u", 1);
relpath_printf(s, perms, "platform/acpi_s3", "%u", 1);
relpath_printf(s, perms, "platform/acpi_s4", "%u", 1);
relpath_printf(s, perms, "platform/acpi_laptop_slate", "%u", 0);
g_list_free_full(perms, g_free);
/* Nodes owned by the guest */
perms = g_list_append(NULL, xs_perm_as_string(XS_PERM_NONE, xen_domid));
relpath_printf(s, perms, "attr", "%s", "");
relpath_printf(s, perms, "control/shutdown", "%s", "");
relpath_printf(s, perms, "control/feature-poweroff", "%u", 1);
relpath_printf(s, perms, "control/feature-reboot", "%u", 1);
relpath_printf(s, perms, "control/feature-suspend", "%u", 1);
relpath_printf(s, perms, "control/feature-s3", "%u", 1);
relpath_printf(s, perms, "control/feature-s4", "%u", 1);
relpath_printf(s, perms, "data", "%s", "");
relpath_printf(s, perms, "device", "%s", "");
relpath_printf(s, perms, "drivers", "%s", "");
relpath_printf(s, perms, "error", "%s", "");
relpath_printf(s, perms, "feature", "%s", "");
g_list_free_full(perms, g_free);
xen_xenstore_ops = &emu_xenstore_backend_ops;
}
static bool xen_xenstore_is_needed(void *opaque)
{
return xen_mode == XEN_EMULATE;
}
static int xen_xenstore_pre_save(void *opaque)
{
XenXenstoreState *s = opaque;
GByteArray *save;
if (s->eh) {
s->guest_port = xen_be_evtchn_get_guest_port(s->eh);
}
g_free(s->impl_state);
save = xs_impl_serialize(s->impl);
s->impl_state = save->data;
s->impl_state_size = save->len;
g_byte_array_free(save, false);
return 0;
}
static int xen_xenstore_post_load(void *opaque, int ver)
{
XenXenstoreState *s = opaque;
GByteArray *save;
int ret;
/*
* As qemu/dom0, rebind to the guest's port. The Windows drivers may
* unbind the XenStore evtchn and rebind to it, having obtained the
* "remote" port through EVTCHNOP_status. In the case that migration
* occurs while it's unbound, the "remote" port needs to be the same
* as before so that the guest can find it, but should remain unbound.
*/
if (s->guest_port) {
int be_port = xen_be_evtchn_bind_interdomain(s->eh, xen_domid,
s->guest_port);
if (be_port < 0) {
return be_port;
}
s->be_port = be_port;
}
save = g_byte_array_new_take(s->impl_state, s->impl_state_size);
s->impl_state = NULL;
s->impl_state_size = 0;
ret = xs_impl_deserialize(s->impl, save, xen_domid, fire_watch_cb, s);
return ret;
}
static const VMStateDescription xen_xenstore_vmstate = {
.name = "xen_xenstore",
.unmigratable = 1, /* The PV back ends don't migrate yet */
.version_id = 1,
.minimum_version_id = 1,
.needed = xen_xenstore_is_needed,
.pre_save = xen_xenstore_pre_save,
.post_load = xen_xenstore_post_load,
.fields = (const VMStateField[]) {
VMSTATE_UINT8_ARRAY(req_data, XenXenstoreState,
sizeof_field(XenXenstoreState, req_data)),
VMSTATE_UINT8_ARRAY(rsp_data, XenXenstoreState,
sizeof_field(XenXenstoreState, rsp_data)),
VMSTATE_UINT32(req_offset, XenXenstoreState),
VMSTATE_UINT32(rsp_offset, XenXenstoreState),
VMSTATE_BOOL(rsp_pending, XenXenstoreState),
VMSTATE_UINT32(guest_port, XenXenstoreState),
VMSTATE_BOOL(fatal_error, XenXenstoreState),
VMSTATE_UINT32(impl_state_size, XenXenstoreState),
VMSTATE_VARRAY_UINT32_ALLOC(impl_state, XenXenstoreState,
impl_state_size, 0,
vmstate_info_uint8, uint8_t),
VMSTATE_END_OF_LIST()
}
};
static void xen_xenstore_class_init(ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS(klass);
dc->realize = xen_xenstore_realize;
dc->vmsd = &xen_xenstore_vmstate;
}
static const TypeInfo xen_xenstore_info = {
.name = TYPE_XEN_XENSTORE,
.parent = TYPE_SYS_BUS_DEVICE,
.instance_size = sizeof(XenXenstoreState),
.class_init = xen_xenstore_class_init,
};
void xen_xenstore_create(void)
{
DeviceState *dev = sysbus_create_simple(TYPE_XEN_XENSTORE, -1, NULL);
xen_xenstore_singleton = XEN_XENSTORE(dev);
/*
* Defer the init (xen_xenstore_reset()) until KVM is set up and the
* overlay page can be mapped.
*/
}
static void xen_xenstore_register_types(void)
{
type_register_static(&xen_xenstore_info);
}
type_init(xen_xenstore_register_types)
uint16_t xen_xenstore_get_port(void)
{
XenXenstoreState *s = xen_xenstore_singleton;
if (!s) {
return 0;
}
return s->guest_port;
}
static bool req_pending(XenXenstoreState *s)
{
struct xsd_sockmsg *req = (struct xsd_sockmsg *)s->req_data;
return s->req_offset == XENSTORE_HEADER_SIZE + req->len;
}
static void reset_req(XenXenstoreState *s)
{
memset(s->req_data, 0, sizeof(s->req_data));
s->req_offset = 0;
}
static void reset_rsp(XenXenstoreState *s)
{
s->rsp_pending = false;
memset(s->rsp_data, 0, sizeof(s->rsp_data));
s->rsp_offset = 0;
}
static void xs_error(XenXenstoreState *s, unsigned int id,
xs_transaction_t tx_id, int errnum)
{
struct xsd_sockmsg *rsp = (struct xsd_sockmsg *)s->rsp_data;
const char *errstr = NULL;
for (unsigned int i = 0; i < ARRAY_SIZE(xsd_errors); i++) {
const struct xsd_errors *xsd_error = &xsd_errors[i];
if (xsd_error->errnum == errnum) {
errstr = xsd_error->errstring;
break;
}
}
assert(errstr);
trace_xenstore_error(id, tx_id, errstr);
rsp->type = XS_ERROR;
rsp->req_id = id;
rsp->tx_id = tx_id;
rsp->len = (uint32_t)strlen(errstr) + 1;
memcpy(&rsp[1], errstr, rsp->len);
}
static void xs_ok(XenXenstoreState *s, unsigned int type, unsigned int req_id,
xs_transaction_t tx_id)
{
struct xsd_sockmsg *rsp = (struct xsd_sockmsg *)s->rsp_data;
const char *okstr = "OK";
rsp->type = type;
rsp->req_id = req_id;
rsp->tx_id = tx_id;
rsp->len = (uint32_t)strlen(okstr) + 1;
memcpy(&rsp[1], okstr, rsp->len);
}
/*
* The correct request and response formats are documented in xen.git:
* docs/misc/xenstore.txt. A summary is given below for convenience.
* The '|' symbol represents a NUL character.
*
* ---------- Database read, write and permissions operations ----------
*
* READ <path>| <value|>
* WRITE <path>|<value|>
* Store and read the octet string <value> at <path>.
* WRITE creates any missing parent paths, with empty values.
*
* MKDIR <path>|
* Ensures that the <path> exists, by necessary by creating
* it and any missing parents with empty values. If <path>
* or any parent already exists, its value is left unchanged.
*
* RM <path>|
* Ensures that the <path> does not exist, by deleting
* it and all of its children. It is not an error if <path> does
* not exist, but it _is_ an error if <path>'s immediate parent
* does not exist either.
*
* DIRECTORY <path>| <child-leaf-name>|*
* Gives a list of the immediate children of <path>, as only the
* leafnames. The resulting children are each named
* <path>/<child-leaf-name>.
*
* DIRECTORY_PART <path>|<offset> <gencnt>|<child-leaf-name>|*
* Same as DIRECTORY, but to be used for children lists longer than
* XENSTORE_PAYLOAD_MAX. Input are <path> and the byte offset into
* the list of children to return. Return values are the generation
* count <gencnt> of the node (to be used to ensure the node hasn't
* changed between two reads: <gencnt> being the same for multiple
* reads guarantees the node hasn't changed) and the list of children
* starting at the specified <offset> of the complete list.
*
* GET_PERMS <path>| <perm-as-string>|+
* SET_PERMS <path>|<perm-as-string>|+?
* <perm-as-string> is one of the following
* w<domid> write only
* r<domid> read only
* b<domid> both read and write
* n<domid> no access
* See https://wiki.xen.org/wiki/XenBus section
* `Permissions' for details of the permissions system.
* It is possible to set permissions for the special watch paths
* "@introduceDomain" and "@releaseDomain" to enable receiving those
* watches in unprivileged domains.
*
* ---------- Watches ----------
*
* WATCH <wpath>|<token>|?
* Adds a watch.
*
* When a <path> is modified (including path creation, removal,
* contents change or permissions change) this generates an event
* on the changed <path>. Changes made in transactions cause an
* event only if and when committed. Each occurring event is
* matched against all the watches currently set up, and each
* matching watch results in a WATCH_EVENT message (see below).
*
* The event's path matches the watch's <wpath> if it is an child
* of <wpath>.
*
* <wpath> can be a <path> to watch or @<wspecial>. In the
* latter case <wspecial> may have any syntax but it matches
* (according to the rules above) only the following special
* events which are invented by xenstored:
* @introduceDomain occurs on INTRODUCE
* @releaseDomain occurs on any domain crash or
* shutdown, and also on RELEASE
* and domain destruction
* <wspecial> events are sent to privileged callers or explicitly
* via SET_PERMS enabled domains only.
*
* When a watch is first set up it is triggered once straight
* away, with <path> equal to <wpath>. Watches may be triggered
* spuriously. The tx_id in a WATCH request is ignored.
*
* Watches are supposed to be restricted by the permissions
* system but in practice the implementation is imperfect.
* Applications should not rely on being sent a notification for
* paths that they cannot read; however, an application may rely
* on being sent a watch when a path which it _is_ able to read
* is deleted even if that leaves only a nonexistent unreadable
* parent. A notification may omitted if a node's permissions
* are changed so as to make it unreadable, in which case future
* notifications may be suppressed (and if the node is later made
* readable, some notifications may have been lost).
*
* WATCH_EVENT <epath>|<token>|
* Unsolicited `reply' generated for matching modification events
* as described above. req_id and tx_id are both 0.
*
* <epath> is the event's path, ie the actual path that was
* modified; however if the event was the recursive removal of an
* parent of <wpath>, <epath> is just
* <wpath> (rather than the actual path which was removed). So
* <epath> is a child of <wpath>, regardless.
*
* Iff <wpath> for the watch was specified as a relative pathname,
* the <epath> path will also be relative (with the same base,
* obviously).
*
* UNWATCH <wpath>|<token>|?
*
* RESET_WATCHES |
* Reset all watches and transactions of the caller.
*
* ---------- Transactions ----------
*
* TRANSACTION_START | <transid>|
* <transid> is an opaque uint32_t allocated by xenstored
* represented as unsigned decimal. After this, transaction may
* be referenced by using <transid> (as 32-bit binary) in the
* tx_id request header field. When transaction is started whole
* db is copied; reads and writes happen on the copy.
* It is not legal to send non-0 tx_id in TRANSACTION_START.
*
* TRANSACTION_END T|
* TRANSACTION_END F|
* tx_id must refer to existing transaction. After this
* request the tx_id is no longer valid and may be reused by
* xenstore. If F, the transaction is discarded. If T,
* it is committed: if there were any other intervening writes
* then our END gets get EAGAIN.
*
* The plan is that in the future only intervening `conflicting'
* writes cause EAGAIN, meaning only writes or other commits
* which changed paths which were read or written in the
* transaction at hand.
*
*/
static void xs_read(XenXenstoreState *s, unsigned int req_id,
xs_transaction_t tx_id, uint8_t *req_data, unsigned int len)
{
const char *path = (const char *)req_data;
struct xsd_sockmsg *rsp = (struct xsd_sockmsg *)s->rsp_data;
uint8_t *rsp_data = (uint8_t *)&rsp[1];
g_autoptr(GByteArray) data = g_byte_array_new();
int err;
if (len == 0 || req_data[len - 1] != '\0') {
xs_error(s, req_id, tx_id, EINVAL);
return;
}
trace_xenstore_read(tx_id, path);
err = xs_impl_read(s->impl, xen_domid, tx_id, path, data);
if (err) {
xs_error(s, req_id, tx_id, err);
return;
}
rsp->type = XS_READ;
rsp->req_id = req_id;
rsp->tx_id = tx_id;
rsp->len = 0;
len = data->len;
if (len > XENSTORE_PAYLOAD_MAX) {
xs_error(s, req_id, tx_id, E2BIG);
return;
}
memcpy(&rsp_data[rsp->len], data->data, len);
rsp->len += len;
}
static void xs_write(XenXenstoreState *s, unsigned int req_id,
xs_transaction_t tx_id, uint8_t *req_data,
unsigned int len)
{
g_autoptr(GByteArray) data = g_byte_array_new();
const char *path;
int err;
if (len == 0) {
xs_error(s, req_id, tx_id, EINVAL);
return;
}
path = (const char *)req_data;
while (len--) {
if (*req_data++ == '\0') {
break;
}
if (len == 0) {
xs_error(s, req_id, tx_id, EINVAL);
return;
}
}
g_byte_array_append(data, req_data, len);
trace_xenstore_write(tx_id, path);
err = xs_impl_write(s->impl, xen_domid, tx_id, path, data);
if (err) {
xs_error(s, req_id, tx_id, err);
return;
}
xs_ok(s, XS_WRITE, req_id, tx_id);
}
static void xs_mkdir(XenXenstoreState *s, unsigned int req_id,
xs_transaction_t tx_id, uint8_t *req_data,
unsigned int len)
{
g_autoptr(GByteArray) data = g_byte_array_new();
const char *path;
int err;
if (len == 0 || req_data[len - 1] != '\0') {
xs_error(s, req_id, tx_id, EINVAL);
return;
}
path = (const char *)req_data;
trace_xenstore_mkdir(tx_id, path);
err = xs_impl_read(s->impl, xen_domid, tx_id, path, data);
if (err == ENOENT) {
err = xs_impl_write(s->impl, xen_domid, tx_id, path, data);
}
if (!err) {
xs_error(s, req_id, tx_id, err);
return;
}
xs_ok(s, XS_MKDIR, req_id, tx_id);
}
static void xs_append_strings(XenXenstoreState *s, struct xsd_sockmsg *rsp,
GList *strings, unsigned int start, bool truncate)
{
uint8_t *rsp_data = (uint8_t *)&rsp[1];
GList *l;
for (l = strings; l; l = l->next) {
size_t len = strlen(l->data) + 1; /* Including the NUL termination */
char *str = l->data;
if (rsp->len + len > XENSTORE_PAYLOAD_MAX) {
if (truncate) {
len = XENSTORE_PAYLOAD_MAX - rsp->len;
if (!len) {
return;
}
} else {
xs_error(s, rsp->req_id, rsp->tx_id, E2BIG);
return;
}
}
if (start) {
if (start >= len) {
start -= len;
continue;
}
str += start;
len -= start;
start = 0;
}
memcpy(&rsp_data[rsp->len], str, len);
rsp->len += len;
}
/* XS_DIRECTORY_PART wants an extra NUL to indicate the end */
if (truncate && rsp->len < XENSTORE_PAYLOAD_MAX) {
rsp_data[rsp->len++] = '\0';
}
}
static void xs_directory(XenXenstoreState *s, unsigned int req_id,
xs_transaction_t tx_id, uint8_t *req_data,
unsigned int len)
{
struct xsd_sockmsg *rsp = (struct xsd_sockmsg *)s->rsp_data;
GList *items = NULL;
const char *path;
int err;
if (len == 0 || req_data[len - 1] != '\0') {
xs_error(s, req_id, tx_id, EINVAL);
return;
}
path = (const char *)req_data;
trace_xenstore_directory(tx_id, path);
err = xs_impl_directory(s->impl, xen_domid, tx_id, path, NULL, &items);
if (err != 0) {
xs_error(s, req_id, tx_id, err);
return;
}
rsp->type = XS_DIRECTORY;
rsp->req_id = req_id;
rsp->tx_id = tx_id;
rsp->len = 0;
xs_append_strings(s, rsp, items, 0, false);
g_list_free_full(items, g_free);
}
static void xs_directory_part(XenXenstoreState *s, unsigned int req_id,
xs_transaction_t tx_id, uint8_t *req_data,
unsigned int len)
{
const char *offset_str, *path = (const char *)req_data;
struct xsd_sockmsg *rsp = (struct xsd_sockmsg *)s->rsp_data;
char *rsp_data = (char *)&rsp[1];
uint64_t gencnt = 0;
unsigned int offset;
GList *items = NULL;
int err;
if (len == 0) {
xs_error(s, req_id, tx_id, EINVAL);
return;
}
while (len--) {
if (*req_data++ == '\0') {
break;
}
if (len == 0) {
xs_error(s, req_id, tx_id, EINVAL);
return;
}
}
offset_str = (const char *)req_data;
while (len--) {
if (*req_data++ == '\0') {
break;
}
if (len == 0) {
xs_error(s, req_id, tx_id, EINVAL);
return;
}
}
if (len) {
xs_error(s, req_id, tx_id, EINVAL);
return;
}
if (qemu_strtoui(offset_str, NULL, 10, &offset) < 0) {
xs_error(s, req_id, tx_id, EINVAL);
return;
}
trace_xenstore_directory_part(tx_id, path, offset);
err = xs_impl_directory(s->impl, xen_domid, tx_id, path, &gencnt, &items);
if (err != 0) {
xs_error(s, req_id, tx_id, err);
return;
}
rsp->type = XS_DIRECTORY_PART;
rsp->req_id = req_id;
rsp->tx_id = tx_id;
rsp->len = snprintf(rsp_data, XENSTORE_PAYLOAD_MAX, "%" PRIu64, gencnt) + 1;
xs_append_strings(s, rsp, items, offset, true);
g_list_free_full(items, g_free);
}
static void xs_transaction_start(XenXenstoreState *s, unsigned int req_id,
xs_transaction_t tx_id, uint8_t *req_data,
unsigned int len)
{
struct xsd_sockmsg *rsp = (struct xsd_sockmsg *)s->rsp_data;
char *rsp_data = (char *)&rsp[1];
int err;
if (len != 1 || req_data[0] != '\0') {
xs_error(s, req_id, tx_id, EINVAL);
return;
}
rsp->type = XS_TRANSACTION_START;
rsp->req_id = req_id;
rsp->tx_id = tx_id;
rsp->len = 0;
err = xs_impl_transaction_start(s->impl, xen_domid, &tx_id);
if (err) {
xs_error(s, req_id, tx_id, err);
return;
}
trace_xenstore_transaction_start(tx_id);
rsp->len = snprintf(rsp_data, XENSTORE_PAYLOAD_MAX, "%u", tx_id);
assert(rsp->len < XENSTORE_PAYLOAD_MAX);
rsp->len++;
}
static void xs_transaction_end(XenXenstoreState *s, unsigned int req_id,
xs_transaction_t tx_id, uint8_t *req_data,
unsigned int len)
{
bool commit;
int err;
if (len != 2 || req_data[1] != '\0') {
xs_error(s, req_id, tx_id, EINVAL);
return;
}
switch (req_data[0]) {
case 'T':
commit = true;
break;
case 'F':
commit = false;
break;
default:
xs_error(s, req_id, tx_id, EINVAL);
return;
}
trace_xenstore_transaction_end(tx_id, commit);
err = xs_impl_transaction_end(s->impl, xen_domid, tx_id, commit);
if (err) {
xs_error(s, req_id, tx_id, err);
return;
}
xs_ok(s, XS_TRANSACTION_END, req_id, tx_id);
}
static void xs_rm(XenXenstoreState *s, unsigned int req_id,
xs_transaction_t tx_id, uint8_t *req_data, unsigned int len)
{
const char *path = (const char *)req_data;
int err;
if (len == 0 || req_data[len - 1] != '\0') {
xs_error(s, req_id, tx_id, EINVAL);
return;
}
trace_xenstore_rm(tx_id, path);
err = xs_impl_rm(s->impl, xen_domid, tx_id, path);
if (err) {
xs_error(s, req_id, tx_id, err);
return;
}
xs_ok(s, XS_RM, req_id, tx_id);
}
static void xs_get_perms(XenXenstoreState *s, unsigned int req_id,
xs_transaction_t tx_id, uint8_t *req_data,
unsigned int len)
{
const char *path = (const char *)req_data;
struct xsd_sockmsg *rsp = (struct xsd_sockmsg *)s->rsp_data;
GList *perms = NULL;
int err;
if (len == 0 || req_data[len - 1] != '\0') {
xs_error(s, req_id, tx_id, EINVAL);
return;
}
trace_xenstore_get_perms(tx_id, path);
err = xs_impl_get_perms(s->impl, xen_domid, tx_id, path, &perms);
if (err) {
xs_error(s, req_id, tx_id, err);
return;
}
rsp->type = XS_GET_PERMS;
rsp->req_id = req_id;
rsp->tx_id = tx_id;
rsp->len = 0;
xs_append_strings(s, rsp, perms, 0, false);
g_list_free_full(perms, g_free);
}
static void xs_set_perms(XenXenstoreState *s, unsigned int req_id,
xs_transaction_t tx_id, uint8_t *req_data,
unsigned int len)
{
const char *path = (const char *)req_data;
uint8_t *perm;
GList *perms = NULL;
int err;
if (len == 0) {
xs_error(s, req_id, tx_id, EINVAL);
return;
}
while (len--) {
if (*req_data++ == '\0') {
break;
}
if (len == 0) {
xs_error(s, req_id, tx_id, EINVAL);
return;
}
}
perm = req_data;
while (len--) {
if (*req_data++ == '\0') {
perms = g_list_append(perms, perm);
perm = req_data;
}
}
/*
* Note that there may be trailing garbage at the end of the buffer.
* This is explicitly permitted by the '?' at the end of the definition:
*
* SET_PERMS <path>|<perm-as-string>|+?
*/
trace_xenstore_set_perms(tx_id, path);
err = xs_impl_set_perms(s->impl, xen_domid, tx_id, path, perms);
g_list_free(perms);
if (err) {
xs_error(s, req_id, tx_id, err);
return;
}
xs_ok(s, XS_SET_PERMS, req_id, tx_id);
}
static void xs_watch(XenXenstoreState *s, unsigned int req_id,
xs_transaction_t tx_id, uint8_t *req_data,
unsigned int len)
{
const char *token, *path = (const char *)req_data;
int err;
if (len == 0) {
xs_error(s, req_id, tx_id, EINVAL);
return;
}
while (len--) {
if (*req_data++ == '\0') {
break;
}
if (len == 0) {
xs_error(s, req_id, tx_id, EINVAL);
return;
}
}
token = (const char *)req_data;
while (len--) {
if (*req_data++ == '\0') {
break;
}
if (len == 0) {
xs_error(s, req_id, tx_id, EINVAL);
return;
}
}
/*
* Note that there may be trailing garbage at the end of the buffer.
* This is explicitly permitted by the '?' at the end of the definition:
*
* WATCH <wpath>|<token>|?
*/
trace_xenstore_watch(path, token);
err = xs_impl_watch(s->impl, xen_domid, path, token, fire_watch_cb, s);
if (err) {
xs_error(s, req_id, tx_id, err);
return;
}
xs_ok(s, XS_WATCH, req_id, tx_id);
}
static void xs_unwatch(XenXenstoreState *s, unsigned int req_id,
xs_transaction_t tx_id, uint8_t *req_data,
unsigned int len)
{
const char *token, *path = (const char *)req_data;
int err;
if (len == 0) {
xs_error(s, req_id, tx_id, EINVAL);
return;
}
while (len--) {
if (*req_data++ == '\0') {
break;
}
if (len == 0) {
xs_error(s, req_id, tx_id, EINVAL);
return;
}
}
token = (const char *)req_data;
while (len--) {
if (*req_data++ == '\0') {
break;
}
if (len == 0) {
xs_error(s, req_id, tx_id, EINVAL);
return;
}
}
trace_xenstore_unwatch(path, token);
err = xs_impl_unwatch(s->impl, xen_domid, path, token, fire_watch_cb, s);
if (err) {
xs_error(s, req_id, tx_id, err);
return;
}
xs_ok(s, XS_UNWATCH, req_id, tx_id);
}
static void xs_reset_watches(XenXenstoreState *s, unsigned int req_id,
xs_transaction_t tx_id, uint8_t *req_data,
unsigned int len)
{
if (len == 0 || req_data[len - 1] != '\0') {
xs_error(s, req_id, tx_id, EINVAL);
return;
}
trace_xenstore_reset_watches();
xs_impl_reset_watches(s->impl, xen_domid);
xs_ok(s, XS_RESET_WATCHES, req_id, tx_id);
}
static void xs_priv(XenXenstoreState *s, unsigned int req_id,
xs_transaction_t tx_id, uint8_t *data,
unsigned int len)
{
xs_error(s, req_id, tx_id, EACCES);
}
static void xs_unimpl(XenXenstoreState *s, unsigned int req_id,
xs_transaction_t tx_id, uint8_t *data,
unsigned int len)
{
xs_error(s, req_id, tx_id, ENOSYS);
}
typedef void (*xs_impl)(XenXenstoreState *s, unsigned int req_id,
xs_transaction_t tx_id, uint8_t *data,
unsigned int len);
struct xsd_req {
const char *name;
xs_impl fn;
};
#define XSD_REQ(_type, _fn) \
[_type] = { .name = #_type, .fn = _fn }
struct xsd_req xsd_reqs[] = {
XSD_REQ(XS_READ, xs_read),
XSD_REQ(XS_WRITE, xs_write),
XSD_REQ(XS_MKDIR, xs_mkdir),
XSD_REQ(XS_DIRECTORY, xs_directory),
XSD_REQ(XS_DIRECTORY_PART, xs_directory_part),
XSD_REQ(XS_TRANSACTION_START, xs_transaction_start),
XSD_REQ(XS_TRANSACTION_END, xs_transaction_end),
XSD_REQ(XS_RM, xs_rm),
XSD_REQ(XS_GET_PERMS, xs_get_perms),
XSD_REQ(XS_SET_PERMS, xs_set_perms),
XSD_REQ(XS_WATCH, xs_watch),
XSD_REQ(XS_UNWATCH, xs_unwatch),
XSD_REQ(XS_CONTROL, xs_priv),
XSD_REQ(XS_INTRODUCE, xs_priv),
XSD_REQ(XS_RELEASE, xs_priv),
XSD_REQ(XS_IS_DOMAIN_INTRODUCED, xs_priv),
XSD_REQ(XS_RESUME, xs_priv),
XSD_REQ(XS_SET_TARGET, xs_priv),
XSD_REQ(XS_RESET_WATCHES, xs_reset_watches),
};
static void process_req(XenXenstoreState *s)
{
struct xsd_sockmsg *req = (struct xsd_sockmsg *)s->req_data;
xs_impl handler = NULL;
assert(req_pending(s));
assert(!s->rsp_pending);
if (req->type < ARRAY_SIZE(xsd_reqs)) {
handler = xsd_reqs[req->type].fn;
}
if (!handler) {
handler = &xs_unimpl;
}
handler(s, req->req_id, req->tx_id, (uint8_t *)&req[1], req->len);
s->rsp_pending = true;
reset_req(s);
}
static unsigned int copy_from_ring(XenXenstoreState *s, uint8_t *ptr,
unsigned int len)
{
if (!len) {
return 0;
}
XENSTORE_RING_IDX prod = qatomic_read(&s->xs->req_prod);
XENSTORE_RING_IDX cons = qatomic_read(&s->xs->req_cons);
unsigned int copied = 0;
/* Ensure the ring contents don't cross the req_prod access. */
smp_rmb();
while (len) {
unsigned int avail = prod - cons;
unsigned int offset = MASK_XENSTORE_IDX(cons);
unsigned int copylen = avail;
if (avail > XENSTORE_RING_SIZE) {
error_report("XenStore ring handling error");
s->fatal_error = true;
break;
} else if (avail == 0) {
break;
}
if (copylen > len) {
copylen = len;
}
if (copylen > XENSTORE_RING_SIZE - offset) {
copylen = XENSTORE_RING_SIZE - offset;
}
memcpy(ptr, &s->xs->req[offset], copylen);
copied += copylen;
ptr += copylen;
len -= copylen;
cons += copylen;
}
/*
* Not sure this ever mattered except on Alpha, but this barrier
* is to ensure that the update to req_cons is globally visible
* only after we have consumed all the data from the ring, and we
* don't end up seeing data written to the ring *after* the other
* end sees the update and writes more to the ring. Xen's own
* xenstored has the same barrier here (although with no comment
* at all, obviously, because it's Xen code).
*/
smp_mb();
qatomic_set(&s->xs->req_cons, cons);
return copied;
}
static unsigned int copy_to_ring(XenXenstoreState *s, uint8_t *ptr,
unsigned int len)
{
if (!len) {
return 0;
}
XENSTORE_RING_IDX cons = qatomic_read(&s->xs->rsp_cons);
XENSTORE_RING_IDX prod = qatomic_read(&s->xs->rsp_prod);
unsigned int copied = 0;
/*
* This matches the barrier in copy_to_ring() (or the guest's
* equivalent) between writing the data to the ring and updating
* rsp_prod. It protects against the pathological case (which
* again I think never happened except on Alpha) where our
* subsequent writes to the ring could *cross* the read of
* rsp_cons and the guest could see the new data when it was
* intending to read the old.
*/
smp_mb();
while (len) {
unsigned int avail = cons + XENSTORE_RING_SIZE - prod;
unsigned int offset = MASK_XENSTORE_IDX(prod);
unsigned int copylen = len;
if (avail > XENSTORE_RING_SIZE) {
error_report("XenStore ring handling error");
s->fatal_error = true;
break;
} else if (avail == 0) {
break;
}
if (copylen > avail) {
copylen = avail;
}
if (copylen > XENSTORE_RING_SIZE - offset) {
copylen = XENSTORE_RING_SIZE - offset;
}
memcpy(&s->xs->rsp[offset], ptr, copylen);
copied += copylen;
ptr += copylen;
len -= copylen;
prod += copylen;
}
/* Ensure the ring contents are seen before rsp_prod update. */
smp_wmb();
qatomic_set(&s->xs->rsp_prod, prod);
return copied;
}
static unsigned int get_req(XenXenstoreState *s)
{
unsigned int copied = 0;
if (s->fatal_error) {
return 0;
}
assert(!req_pending(s));
if (s->req_offset < XENSTORE_HEADER_SIZE) {
void *ptr = s->req_data + s->req_offset;
unsigned int len = XENSTORE_HEADER_SIZE;
unsigned int copylen = copy_from_ring(s, ptr, len);
copied += copylen;
s->req_offset += copylen;
}
if (s->req_offset >= XENSTORE_HEADER_SIZE) {
struct xsd_sockmsg *req = (struct xsd_sockmsg *)s->req_data;
if (req->len > (uint32_t)XENSTORE_PAYLOAD_MAX) {
error_report("Illegal XenStore request");
s->fatal_error = true;
return 0;
}
void *ptr = s->req_data + s->req_offset;
unsigned int len = XENSTORE_HEADER_SIZE + req->len - s->req_offset;
unsigned int copylen = copy_from_ring(s, ptr, len);
copied += copylen;
s->req_offset += copylen;
}
return copied;
}
static unsigned int put_rsp(XenXenstoreState *s)
{
if (s->fatal_error) {
return 0;
}
assert(s->rsp_pending);
struct xsd_sockmsg *rsp = (struct xsd_sockmsg *)s->rsp_data;
assert(s->rsp_offset < XENSTORE_HEADER_SIZE + rsp->len);
void *ptr = s->rsp_data + s->rsp_offset;
unsigned int len = XENSTORE_HEADER_SIZE + rsp->len - s->rsp_offset;
unsigned int copylen = copy_to_ring(s, ptr, len);
s->rsp_offset += copylen;
/* Have we produced a complete response? */
if (s->rsp_offset == XENSTORE_HEADER_SIZE + rsp->len) {
reset_rsp(s);
}
return copylen;
}
static void deliver_watch(XenXenstoreState *s, const char *path,
const char *token)
{
struct xsd_sockmsg *rsp = (struct xsd_sockmsg *)s->rsp_data;
uint8_t *rsp_data = (uint8_t *)&rsp[1];
unsigned int len;
assert(!s->rsp_pending);
trace_xenstore_watch_event(path, token);
rsp->type = XS_WATCH_EVENT;
rsp->req_id = 0;
rsp->tx_id = 0;
rsp->len = 0;
len = strlen(path);
/* XENSTORE_ABS/REL_PATH_MAX should ensure there can be no overflow */
assert(rsp->len + len < XENSTORE_PAYLOAD_MAX);
memcpy(&rsp_data[rsp->len], path, len);
rsp->len += len;
rsp_data[rsp->len] = '\0';
rsp->len++;
len = strlen(token);
/*
* It is possible for the guest to have chosen a token that will
* not fit (along with the patch) into a watch event. We have no
* choice but to drop the event if this is the case.
*/
if (rsp->len + len >= XENSTORE_PAYLOAD_MAX) {
return;
}
memcpy(&rsp_data[rsp->len], token, len);
rsp->len += len;
rsp_data[rsp->len] = '\0';
rsp->len++;
s->rsp_pending = true;
}
struct watch_event {
char *path;
char *token;
};
static void free_watch_event(struct watch_event *ev)
{
if (ev) {
g_free(ev->path);
g_free(ev->token);
g_free(ev);
}
}
static void queue_watch(XenXenstoreState *s, const char *path,
const char *token)
{
struct watch_event *ev = g_new0(struct watch_event, 1);
ev->path = g_strdup(path);
ev->token = g_strdup(token);
s->watch_events = g_list_append(s->watch_events, ev);
}
static void fire_watch_cb(void *opaque, const char *path, const char *token)
{
XenXenstoreState *s = opaque;
assert(bql_locked());
/*
* If there's a response pending, we obviously can't scribble over
* it. But if there's a request pending, it has dibs on the buffer
* too.
*
* In the common case of a watch firing due to backend activity
* when the ring was otherwise idle, we should be able to copy the
* strings directly into the rsp_data and thence the actual ring,
* without needing to perform any allocations and queue them.
*/
if (s->rsp_pending || req_pending(s)) {
queue_watch(s, path, token);
} else {
deliver_watch(s, path, token);
/*
* Attempt to queue the message into the actual ring, and send
* the event channel notification if any bytes are copied.
*/
if (s->rsp_pending && put_rsp(s) > 0) {
xen_be_evtchn_notify(s->eh, s->be_port);
}
}
}
static void process_watch_events(XenXenstoreState *s)
{
struct watch_event *ev = s->watch_events->data;
deliver_watch(s, ev->path, ev->token);
s->watch_events = g_list_remove(s->watch_events, ev);
free_watch_event(ev);
}
static void xen_xenstore_event(void *opaque)
{
XenXenstoreState *s = opaque;
evtchn_port_t port = xen_be_evtchn_pending(s->eh);
unsigned int copied_to, copied_from;
bool processed, notify = false;
if (port != s->be_port) {
return;
}
/* We know this is a no-op. */
xen_be_evtchn_unmask(s->eh, port);
do {
copied_to = copied_from = 0;
processed = false;
if (!s->rsp_pending && s->watch_events) {
process_watch_events(s);
}
if (s->rsp_pending) {
copied_to = put_rsp(s);
}
if (!req_pending(s)) {
copied_from = get_req(s);
}
if (req_pending(s) && !s->rsp_pending && !s->watch_events) {
process_req(s);
processed = true;
}
notify |= copied_to || copied_from;
} while (copied_to || copied_from || processed);
if (notify) {
xen_be_evtchn_notify(s->eh, s->be_port);
}
}
static void alloc_guest_port(XenXenstoreState *s)
{
struct evtchn_alloc_unbound alloc = {
.dom = DOMID_SELF,
.remote_dom = DOMID_QEMU,
};
if (!xen_evtchn_alloc_unbound_op(&alloc)) {
s->guest_port = alloc.port;
}
}
int xen_xenstore_reset(void)
{
XenXenstoreState *s = xen_xenstore_singleton;
int console_port;
GList *perms;
int err;
if (!s) {
return -ENOTSUP;
}
s->req_offset = s->rsp_offset = 0;
s->rsp_pending = false;
if (!memory_region_is_mapped(&s->xenstore_page)) {
uint64_t gpa = XEN_SPECIAL_PFN(XENSTORE) << TARGET_PAGE_BITS;
xen_overlay_do_map_page(&s->xenstore_page, gpa);
}
alloc_guest_port(s);
/*
* As qemu/dom0, bind to the guest's port. For incoming migration, this
* will be unbound as the guest's evtchn table is overwritten. We then
* rebind to the correct guest port in xen_xenstore_post_load().
*/
err = xen_be_evtchn_bind_interdomain(s->eh, xen_domid, s->guest_port);
if (err < 0) {
return err;
}
s->be_port = err;
/* Create frontend store nodes */
perms = g_list_append(NULL, xs_perm_as_string(XS_PERM_NONE, DOMID_QEMU));
perms = g_list_append(perms, xs_perm_as_string(XS_PERM_READ, xen_domid));
relpath_printf(s, perms, "store/port", "%u", s->guest_port);
relpath_printf(s, perms, "store/ring-ref", "%lu",
XEN_SPECIAL_PFN(XENSTORE));
console_port = xen_primary_console_get_port();
if (console_port) {
relpath_printf(s, perms, "console/ring-ref", "%lu",
XEN_SPECIAL_PFN(CONSOLE));
relpath_printf(s, perms, "console/port", "%u", console_port);
relpath_printf(s, perms, "console/state", "%u", XenbusStateInitialised);
}
g_list_free_full(perms, g_free);
/*
* We don't actually access the guest's page through the grant, because
* this isn't real Xen, and we can just use the page we gave it in the
* first place. Map the grant anyway, mostly for cosmetic purposes so
* it *looks* like it's in use in the guest-visible grant table.
*/
s->gt = qemu_xen_gnttab_open();
uint32_t xs_gntref = GNTTAB_RESERVED_XENSTORE;
s->granted_xs = qemu_xen_gnttab_map_refs(s->gt, 1, xen_domid, &xs_gntref,
PROT_READ | PROT_WRITE);
return 0;
}
struct qemu_xs_handle {
XenstoreImplState *impl;
GList *watches;
QEMUBH *watch_bh;
};
struct qemu_xs_watch {
struct qemu_xs_handle *h;
char *path;
xs_watch_fn fn;
void *opaque;
GList *events;
};
static char *xs_be_get_domain_path(struct qemu_xs_handle *h, unsigned int domid)
{
return g_strdup_printf("/local/domain/%u", domid);
}
static char **xs_be_directory(struct qemu_xs_handle *h, xs_transaction_t t,
const char *path, unsigned int *num)
{
GList *items = NULL, *l;
unsigned int i = 0;
char **items_ret;
int err;
err = xs_impl_directory(h->impl, DOMID_QEMU, t, path, NULL, &items);
if (err) {
errno = err;
return NULL;
}
items_ret = g_new0(char *, g_list_length(items) + 1);
*num = 0;
for (l = items; l; l = l->next) {
items_ret[i++] = l->data;
(*num)++;
}
g_list_free(items);
return items_ret;
}
static void *xs_be_read(struct qemu_xs_handle *h, xs_transaction_t t,
const char *path, unsigned int *len)
{
GByteArray *data = g_byte_array_new();
bool free_segment = false;
int err;
err = xs_impl_read(h->impl, DOMID_QEMU, t, path, data);
if (err) {
free_segment = true;
errno = err;
} else {
if (len) {
*len = data->len;
}
/* The xen-bus-helper code expects to get NUL terminated string! */
g_byte_array_append(data, (void *)"", 1);
}
return g_byte_array_free(data, free_segment);
}
static bool xs_be_write(struct qemu_xs_handle *h, xs_transaction_t t,
const char *path, const void *data, unsigned int len)
{
GByteArray *gdata = g_byte_array_new();
int err;
g_byte_array_append(gdata, data, len);
err = xs_impl_write(h->impl, DOMID_QEMU, t, path, gdata);
g_byte_array_unref(gdata);
if (err) {
errno = err;
return false;
}
return true;
}
static bool xs_be_create(struct qemu_xs_handle *h, xs_transaction_t t,
unsigned int owner, unsigned int domid,
unsigned int perms, const char *path)
{
g_autoptr(GByteArray) data = g_byte_array_new();
GList *perms_list = NULL;
int err;
/* mkdir does this */
err = xs_impl_read(h->impl, DOMID_QEMU, t, path, data);
if (err == ENOENT) {
err = xs_impl_write(h->impl, DOMID_QEMU, t, path, data);
}
if (err) {
errno = err;
return false;
}
perms_list = g_list_append(perms_list,
xs_perm_as_string(XS_PERM_NONE, owner));
perms_list = g_list_append(perms_list,
xs_perm_as_string(perms, domid));
err = xs_impl_set_perms(h->impl, DOMID_QEMU, t, path, perms_list);
g_list_free_full(perms_list, g_free);
if (err) {
errno = err;
return false;
}
return true;
}
static bool xs_be_destroy(struct qemu_xs_handle *h, xs_transaction_t t,
const char *path)
{
int err = xs_impl_rm(h->impl, DOMID_QEMU, t, path);
if (err) {
errno = err;
return false;
}
return true;
}
static void be_watch_bh(void *_h)
{
struct qemu_xs_handle *h = _h;
GList *l;
for (l = h->watches; l; l = l->next) {
struct qemu_xs_watch *w = l->data;
while (w->events) {
struct watch_event *ev = w->events->data;
w->fn(w->opaque, ev->path);
w->events = g_list_remove(w->events, ev);
free_watch_event(ev);
}
}
}
static void xs_be_watch_cb(void *opaque, const char *path, const char *token)
{
struct watch_event *ev = g_new0(struct watch_event, 1);
struct qemu_xs_watch *w = opaque;
/* We don't care about the token */
ev->path = g_strdup(path);
w->events = g_list_append(w->events, ev);
qemu_bh_schedule(w->h->watch_bh);
}
static struct qemu_xs_watch *xs_be_watch(struct qemu_xs_handle *h,
const char *path, xs_watch_fn fn,
void *opaque)
{
struct qemu_xs_watch *w = g_new0(struct qemu_xs_watch, 1);
int err;
w->h = h;
w->fn = fn;
w->opaque = opaque;
err = xs_impl_watch(h->impl, DOMID_QEMU, path, NULL, xs_be_watch_cb, w);
if (err) {
errno = err;
g_free(w);
return NULL;
}
w->path = g_strdup(path);
h->watches = g_list_append(h->watches, w);
return w;
}
static void xs_be_unwatch(struct qemu_xs_handle *h, struct qemu_xs_watch *w)
{
xs_impl_unwatch(h->impl, DOMID_QEMU, w->path, NULL, xs_be_watch_cb, w);
h->watches = g_list_remove(h->watches, w);
g_list_free_full(w->events, (GDestroyNotify)free_watch_event);
g_free(w->path);
g_free(w);
}
static xs_transaction_t xs_be_transaction_start(struct qemu_xs_handle *h)
{
unsigned int new_tx = XBT_NULL;
int err = xs_impl_transaction_start(h->impl, DOMID_QEMU, &new_tx);
if (err) {
errno = err;
return XBT_NULL;
}
return new_tx;
}
static bool xs_be_transaction_end(struct qemu_xs_handle *h, xs_transaction_t t,
bool abort)
{
int err = xs_impl_transaction_end(h->impl, DOMID_QEMU, t, !abort);
if (err) {
errno = err;
return false;
}
return true;
}
static struct qemu_xs_handle *xs_be_open(void)
{
XenXenstoreState *s = xen_xenstore_singleton;
struct qemu_xs_handle *h;
if (!s || !s->impl) {
errno = -ENOSYS;
return NULL;
}
h = g_new0(struct qemu_xs_handle, 1);
h->impl = s->impl;
h->watch_bh = aio_bh_new(qemu_get_aio_context(), be_watch_bh, h);
return h;
}
static void xs_be_close(struct qemu_xs_handle *h)
{
while (h->watches) {
struct qemu_xs_watch *w = h->watches->data;
xs_be_unwatch(h, w);
}
qemu_bh_delete(h->watch_bh);
g_free(h);
}
static struct xenstore_backend_ops emu_xenstore_backend_ops = {
.open = xs_be_open,
.close = xs_be_close,
.get_domain_path = xs_be_get_domain_path,
.directory = xs_be_directory,
.read = xs_be_read,
.write = xs_be_write,
.create = xs_be_create,
.destroy = xs_be_destroy,
.watch = xs_be_watch,
.unwatch = xs_be_unwatch,
.transaction_start = xs_be_transaction_start,
.transaction_end = xs_be_transaction_end,
};
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