a783f8ad4e
...that maintains compatibility with existing Xen toolstacks.
Xen toolstacks instantiate PV backends by simply writing information into
xenstore and expecting a backend implementation to be watching for this.
This patch adds a new 'xen-backend' module to allow individual XenDevice
implementations to register create and destroy functions. The creator
will be called when a tool-stack instantiates a new backend in this way,
and the destructor will then be called after the resulting XenDevice
object is unrealized.
To support this it is also necessary to add new watchers into the XenBus
implementation to handle enumeration of new backends and also destruction
of XenDevice-s when the toolstack sets the backend 'online' key to 0.
NOTE: This patch only adds the framework. A subsequent patch will add a
creator function for xen-block devices.
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>
166 lines
3.6 KiB
C
166 lines
3.6 KiB
C
/*
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* Copyright (c) 2018 Citrix Systems Inc.
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or later.
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* See the COPYING file in the top-level directory.
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*/
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#include "qemu/osdep.h"
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#include "qemu/error-report.h"
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#include "qapi/error.h"
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#include "hw/xen/xen-backend.h"
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#include "hw/xen/xen-bus.h"
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typedef struct XenBackendImpl {
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const char *type;
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XenBackendDeviceCreate create;
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XenBackendDeviceDestroy destroy;
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} XenBackendImpl;
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struct XenBackendInstance {
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QLIST_ENTRY(XenBackendInstance) entry;
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const XenBackendImpl *impl;
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XenBus *xenbus;
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char *name;
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XenDevice *xendev;
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};
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static GHashTable *xen_backend_table_get(void)
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{
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static GHashTable *table;
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if (table == NULL) {
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table = g_hash_table_new(g_str_hash, g_str_equal);
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}
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return table;
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}
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static void xen_backend_table_add(XenBackendImpl *impl)
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{
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g_hash_table_insert(xen_backend_table_get(), (void *)impl->type, impl);
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}
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static const XenBackendImpl *xen_backend_table_lookup(const char *type)
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{
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return g_hash_table_lookup(xen_backend_table_get(), type);
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}
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void xen_backend_register(const XenBackendInfo *info)
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{
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XenBackendImpl *impl = g_new0(XenBackendImpl, 1);
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g_assert(info->type);
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if (xen_backend_table_lookup(info->type)) {
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error_report("attempt to register duplicate Xen backend type '%s'",
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info->type);
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abort();
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}
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if (!info->create) {
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error_report("backend type '%s' has no creator", info->type);
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abort();
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}
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impl->type = info->type;
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impl->create = info->create;
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impl->destroy = info->destroy;
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xen_backend_table_add(impl);
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}
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static QLIST_HEAD(, XenBackendInstance) backend_list;
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static void xen_backend_list_add(XenBackendInstance *backend)
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{
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QLIST_INSERT_HEAD(&backend_list, backend, entry);
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}
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static XenBackendInstance *xen_backend_list_find(XenDevice *xendev)
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{
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XenBackendInstance *backend;
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QLIST_FOREACH(backend, &backend_list, entry) {
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if (backend->xendev == xendev) {
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return backend;
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}
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}
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return NULL;
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}
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static void xen_backend_list_remove(XenBackendInstance *backend)
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{
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QLIST_REMOVE(backend, entry);
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}
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void xen_backend_device_create(XenBus *xenbus, const char *type,
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const char *name, QDict *opts, Error **errp)
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{
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const XenBackendImpl *impl = xen_backend_table_lookup(type);
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XenBackendInstance *backend;
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Error *local_error = NULL;
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if (!impl) {
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return;
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}
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backend = g_new0(XenBackendInstance, 1);
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backend->xenbus = xenbus;
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backend->name = g_strdup(name);
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impl->create(backend, opts, &local_error);
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if (local_error) {
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error_propagate(errp, local_error);
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g_free(backend->name);
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g_free(backend);
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return;
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}
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backend->impl = impl;
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xen_backend_list_add(backend);
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}
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XenBus *xen_backend_get_bus(XenBackendInstance *backend)
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{
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return backend->xenbus;
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}
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const char *xen_backend_get_name(XenBackendInstance *backend)
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{
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return backend->name;
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}
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void xen_backend_set_device(XenBackendInstance *backend,
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XenDevice *xendev)
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{
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g_assert(!backend->xendev);
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backend->xendev = xendev;
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}
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XenDevice *xen_backend_get_device(XenBackendInstance *backend)
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{
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return backend->xendev;
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}
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bool xen_backend_try_device_destroy(XenDevice *xendev, Error **errp)
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{
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XenBackendInstance *backend = xen_backend_list_find(xendev);
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const XenBackendImpl *impl;
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if (!backend) {
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return false;
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}
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impl = backend->impl;
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impl->destroy(backend, errp);
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xen_backend_list_remove(backend);
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g_free(backend->name);
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g_free(backend);
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return true;
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}
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