| 1 | /* |
| 2 | * Persistent reservation manager that talks to qemu-pr-helper |
| 3 | * |
| 4 | * Copyright (c) 2017 Red Hat, Inc. |
| 5 | * |
| 6 | * Author: Paolo Bonzini <pbonzini@redhat.com> |
| 7 | * |
| 8 | * This code is licensed under the LGPL v2.1 or later. |
| 9 | * |
| 10 | */ |
| 11 | |
| 12 | #include "qemu/osdep.h" |
| 13 | #include "qapi/error.h" |
| 14 | #include "scsi/constants.h" |
| 15 | #include "scsi/pr-manager.h" |
| 16 | #include "scsi/utils.h" |
| 17 | #include "io/channel.h" |
| 18 | #include "io/channel-socket.h" |
| 19 | #include "pr-helper.h" |
| 20 | #include "qapi/qapi-events-block.h" |
| 21 | #include "qemu/module.h" |
| 22 | #include "qemu/bswap.h" |
| 23 | |
| 24 | #include <scsi/sg.h> |
| 25 | #include "qom/object.h" |
| 26 | |
| 27 | #define PR_MAX_RECONNECT_ATTEMPTS 5 |
| 28 | |
| 29 | #define TYPE_PR_MANAGER_HELPER "pr-manager-helper" |
| 30 | |
| 31 | OBJECT_DECLARE_SIMPLE_TYPE(PRManagerHelper, PR_MANAGER_HELPER) |
| 32 | |
| 33 | struct PRManagerHelper { |
| 34 | /* <private> */ |
| 35 | PRManager parent; |
| 36 | |
| 37 | char *path; |
| 38 | |
| 39 | QemuMutex lock; |
| 40 | QIOChannel *ioc; |
| 41 | }; |
| 42 | |
| 43 | static void pr_manager_send_status_changed_event(PRManagerHelper *pr_mgr) |
| 44 | { |
| 45 | const char *id = object_get_canonical_path_component(OBJECT(pr_mgr)); |
| 46 | |
| 47 | if (id) { |
| 48 | qapi_event_send_pr_manager_status_changed(id, !!pr_mgr->ioc); |
| 49 | } |
| 50 | } |
| 51 | |
| 52 | /* Called with lock held. */ |
| 53 | static int pr_manager_helper_read(PRManagerHelper *pr_mgr, |
| 54 | void *buf, int sz, Error **errp) |
| 55 | { |
| 56 | ssize_t r = qio_channel_read_all(pr_mgr->ioc, buf, sz, errp); |
| 57 | |
| 58 | if (r < 0) { |
| 59 | object_unref(OBJECT(pr_mgr->ioc)); |
| 60 | pr_mgr->ioc = NULL; |
| 61 | pr_manager_send_status_changed_event(pr_mgr); |
| 62 | return -EINVAL; |
| 63 | } |
| 64 | |
| 65 | return 0; |
| 66 | } |
| 67 | |
| 68 | /* Called with lock held. */ |
| 69 | static int pr_manager_helper_write(PRManagerHelper *pr_mgr, |
| 70 | int fd, |
| 71 | const void *buf, int sz, Error **errp) |
| 72 | { |
| 73 | size_t nfds = (fd != -1); |
| 74 | while (sz > 0) { |
| 75 | struct iovec iov; |
| 76 | ssize_t n_written; |
| 77 | |
| 78 | iov.iov_base = (void *)buf; |
| 79 | iov.iov_len = sz; |
| 80 | n_written = qio_channel_writev_full(QIO_CHANNEL(pr_mgr->ioc), &iov, 1, |
| 81 | nfds ? &fd : NULL, nfds, 0, errp); |
| 82 | |
| 83 | if (n_written <= 0) { |
| 84 | assert(n_written != QIO_CHANNEL_ERR_BLOCK); |
| 85 | object_unref(OBJECT(pr_mgr->ioc)); |
| 86 | pr_mgr->ioc = NULL; |
| 87 | pr_manager_send_status_changed_event(pr_mgr); |
| 88 | return n_written < 0 ? -EINVAL : 0; |
| 89 | } |
| 90 | |
| 91 | nfds = 0; |
| 92 | buf += n_written; |
| 93 | sz -= n_written; |
| 94 | } |
| 95 | |
| 96 | return 0; |
| 97 | } |
| 98 | |
| 99 | /* Called with lock held. */ |
| 100 | static int pr_manager_helper_initialize(PRManagerHelper *pr_mgr, |
| 101 | Error **errp) |
| 102 | { |
| 103 | char *path = g_strdup(pr_mgr->path); |
| 104 | SocketAddress saddr = { |
| 105 | .type = SOCKET_ADDRESS_TYPE_UNIX, |
| 106 | .u.q_unix.path = path |
| 107 | }; |
| 108 | QIOChannelSocket *sioc = qio_channel_socket_new(); |
| 109 | uint32_t flags; |
| 110 | int r; |
| 111 | |
| 112 | assert(!pr_mgr->ioc); |
| 113 | qio_channel_set_name(QIO_CHANNEL(sioc), "pr-manager-helper"); |
| 114 | r = qio_channel_socket_connect_sync(sioc, &saddr, errp); |
| 115 | g_free(path); |
| 116 | if (r < 0) { |
| 117 | object_unref(OBJECT(sioc)); |
| 118 | return -ENOTCONN; |
| 119 | } |
| 120 | |
| 121 | qio_channel_set_delay(QIO_CHANNEL(sioc), false); |
| 122 | pr_mgr->ioc = QIO_CHANNEL(sioc); |
| 123 | |
| 124 | /* A simple feature negotiation protocol, even though there is |
| 125 | * no optional feature right now. |
| 126 | */ |
| 127 | r = pr_manager_helper_read(pr_mgr, &flags, sizeof(flags), errp); |
| 128 | if (r < 0) { |
| 129 | goto out_close; |
| 130 | } |
| 131 | |
| 132 | flags = 0; |
| 133 | r = pr_manager_helper_write(pr_mgr, -1, &flags, sizeof(flags), errp); |
| 134 | if (r < 0) { |
| 135 | goto out_close; |
| 136 | } |
| 137 | |
| 138 | pr_manager_send_status_changed_event(pr_mgr); |
| 139 | return 0; |
| 140 | |
| 141 | out_close: |
| 142 | object_unref(OBJECT(pr_mgr->ioc)); |
| 143 | pr_mgr->ioc = NULL; |
| 144 | return r; |
| 145 | } |
| 146 | |
| 147 | static int pr_manager_helper_run(PRManager *p, |
| 148 | int fd, struct sg_io_hdr *io_hdr) |
| 149 | { |
| 150 | PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(p); |
| 151 | |
| 152 | uint32_t len; |
| 153 | PRHelperResponse resp; |
| 154 | int ret; |
| 155 | int expected_dir; |
| 156 | int attempts; |
| 157 | uint8_t cdb[PR_HELPER_CDB_SIZE] = { 0 }; |
| 158 | |
| 159 | if (!io_hdr->cmd_len || io_hdr->cmd_len > PR_HELPER_CDB_SIZE) { |
| 160 | return -EINVAL; |
| 161 | } |
| 162 | |
| 163 | memcpy(cdb, io_hdr->cmdp, io_hdr->cmd_len); |
| 164 | assert(cdb[0] == PERSISTENT_RESERVE_OUT || cdb[0] == PERSISTENT_RESERVE_IN); |
| 165 | expected_dir = |
| 166 | (cdb[0] == PERSISTENT_RESERVE_OUT ? SG_DXFER_TO_DEV : SG_DXFER_FROM_DEV); |
| 167 | if (io_hdr->dxfer_direction != expected_dir) { |
| 168 | return -EINVAL; |
| 169 | } |
| 170 | |
| 171 | len = scsi_cdb_xfer(cdb); |
| 172 | if (io_hdr->dxfer_len < len || len > PR_HELPER_DATA_SIZE) { |
| 173 | return -EINVAL; |
| 174 | } |
| 175 | |
| 176 | qemu_mutex_lock(&pr_mgr->lock); |
| 177 | |
| 178 | /* Try to reconnect while sending the CDB. */ |
| 179 | for (attempts = 0; attempts < PR_MAX_RECONNECT_ATTEMPTS; attempts++) { |
| 180 | if (!pr_mgr->ioc) { |
| 181 | ret = pr_manager_helper_initialize(pr_mgr, NULL); |
| 182 | if (ret < 0) { |
| 183 | qemu_mutex_unlock(&pr_mgr->lock); |
| 184 | g_usleep(G_USEC_PER_SEC); |
| 185 | qemu_mutex_lock(&pr_mgr->lock); |
| 186 | continue; |
| 187 | } |
| 188 | } |
| 189 | |
| 190 | ret = pr_manager_helper_write(pr_mgr, fd, cdb, ARRAY_SIZE(cdb), NULL); |
| 191 | if (ret >= 0) { |
| 192 | break; |
| 193 | } |
| 194 | } |
| 195 | if (ret < 0) { |
| 196 | goto out; |
| 197 | } |
| 198 | |
| 199 | /* After sending the CDB, any communications failure causes the |
| 200 | * command to fail. The failure is transient, retrying the command |
| 201 | * will invoke pr_manager_helper_initialize again. |
| 202 | */ |
| 203 | if (expected_dir == SG_DXFER_TO_DEV) { |
| 204 | io_hdr->resid = io_hdr->dxfer_len - len; |
| 205 | ret = pr_manager_helper_write(pr_mgr, -1, io_hdr->dxferp, len, NULL); |
| 206 | if (ret < 0) { |
| 207 | goto out; |
| 208 | } |
| 209 | } |
| 210 | ret = pr_manager_helper_read(pr_mgr, &resp, sizeof(resp), NULL); |
| 211 | if (ret < 0) { |
| 212 | goto out; |
| 213 | } |
| 214 | |
| 215 | resp.result = be32_to_cpu(resp.result); |
| 216 | resp.sz = be32_to_cpu(resp.sz); |
| 217 | if (io_hdr->dxfer_direction == SG_DXFER_FROM_DEV) { |
| 218 | assert(resp.sz <= io_hdr->dxfer_len); |
| 219 | ret = pr_manager_helper_read(pr_mgr, io_hdr->dxferp, resp.sz, NULL); |
| 220 | if (ret < 0) { |
| 221 | goto out; |
| 222 | } |
| 223 | io_hdr->resid = io_hdr->dxfer_len - resp.sz; |
| 224 | } else { |
| 225 | assert(resp.sz == 0); |
| 226 | } |
| 227 | |
| 228 | io_hdr->status = resp.result; |
| 229 | if (resp.result == CHECK_CONDITION) { |
| 230 | io_hdr->driver_status = SG_ERR_DRIVER_SENSE; |
| 231 | io_hdr->sb_len_wr = MIN(io_hdr->mx_sb_len, PR_HELPER_SENSE_SIZE); |
| 232 | memcpy(io_hdr->sbp, resp.sense, io_hdr->sb_len_wr); |
| 233 | } |
| 234 | |
| 235 | out: |
| 236 | if (ret < 0) { |
| 237 | int sense_len = scsi_build_sense(io_hdr->sbp, |
| 238 | SENSE_CODE(LUN_COMM_FAILURE)); |
| 239 | io_hdr->driver_status = SG_ERR_DRIVER_SENSE; |
| 240 | io_hdr->sb_len_wr = MIN(io_hdr->mx_sb_len, sense_len); |
| 241 | io_hdr->status = CHECK_CONDITION; |
| 242 | } |
| 243 | qemu_mutex_unlock(&pr_mgr->lock); |
| 244 | return ret; |
| 245 | } |
| 246 | |
| 247 | static bool pr_manager_helper_is_connected(PRManager *p) |
| 248 | { |
| 249 | PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(p); |
| 250 | bool result; |
| 251 | |
| 252 | qemu_mutex_lock(&pr_mgr->lock); |
| 253 | result = (pr_mgr->ioc != NULL); |
| 254 | qemu_mutex_unlock(&pr_mgr->lock); |
| 255 | |
| 256 | return result; |
| 257 | } |
| 258 | |
| 259 | static void pr_manager_helper_complete(UserCreatable *uc, Error **errp) |
| 260 | { |
| 261 | PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(uc); |
| 262 | |
| 263 | qemu_mutex_lock(&pr_mgr->lock); |
| 264 | pr_manager_helper_initialize(pr_mgr, errp); |
| 265 | qemu_mutex_unlock(&pr_mgr->lock); |
| 266 | } |
| 267 | |
| 268 | static char *get_path(Object *obj, Error **errp) |
| 269 | { |
| 270 | PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(obj); |
| 271 | |
| 272 | return g_strdup(pr_mgr->path); |
| 273 | } |
| 274 | |
| 275 | static void set_path(Object *obj, const char *str, Error **errp) |
| 276 | { |
| 277 | PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(obj); |
| 278 | |
| 279 | g_free(pr_mgr->path); |
| 280 | pr_mgr->path = g_strdup(str); |
| 281 | } |
| 282 | |
| 283 | static void pr_manager_helper_instance_finalize(Object *obj) |
| 284 | { |
| 285 | PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(obj); |
| 286 | |
| 287 | g_free(pr_mgr->path); |
| 288 | object_unref(OBJECT(pr_mgr->ioc)); |
| 289 | qemu_mutex_destroy(&pr_mgr->lock); |
| 290 | } |
| 291 | |
| 292 | static void pr_manager_helper_instance_init(Object *obj) |
| 293 | { |
| 294 | PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(obj); |
| 295 | |
| 296 | qemu_mutex_init(&pr_mgr->lock); |
| 297 | } |
| 298 | |
| 299 | static void pr_manager_helper_class_init(ObjectClass *klass, |
| 300 | const void *class_data G_GNUC_UNUSED) |
| 301 | { |
| 302 | PRManagerClass *prmgr_klass = PR_MANAGER_CLASS(klass); |
| 303 | UserCreatableClass *uc_klass = USER_CREATABLE_CLASS(klass); |
| 304 | |
| 305 | object_class_property_add_str(klass, "path", get_path, set_path); |
| 306 | uc_klass->complete = pr_manager_helper_complete; |
| 307 | prmgr_klass->run = pr_manager_helper_run; |
| 308 | prmgr_klass->is_connected = pr_manager_helper_is_connected; |
| 309 | } |
| 310 | |
| 311 | static const TypeInfo pr_manager_helper_info = { |
| 312 | .parent = TYPE_PR_MANAGER, |
| 313 | .name = TYPE_PR_MANAGER_HELPER, |
| 314 | .instance_size = sizeof(PRManagerHelper), |
| 315 | .instance_init = pr_manager_helper_instance_init, |
| 316 | .instance_finalize = pr_manager_helper_instance_finalize, |
| 317 | .class_init = pr_manager_helper_class_init, |
| 318 | }; |
| 319 | |
| 320 | static void pr_manager_helper_register_types(void) |
| 321 | { |
| 322 | type_register_static(&pr_manager_helper_info); |
| 323 | } |
| 324 | |
| 325 | type_init(pr_manager_helper_register_types); |