xref: /openbmc/qemu/scsi/pr-manager-helper.c (revision 5f640894) 
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 
21 #include <scsi/sg.h>
22 
23 #define PR_MAX_RECONNECT_ATTEMPTS 5
24 
25 #define TYPE_PR_MANAGER_HELPER "pr-manager-helper"
26 
27 #define PR_MANAGER_HELPER(obj) \
28      OBJECT_CHECK(PRManagerHelper, (obj), \
29                   TYPE_PR_MANAGER_HELPER)
30 
31 typedef struct PRManagerHelper {
32     /* <private> */
33     PRManager parent;
34 
35     char *path;
36 
37     QemuMutex lock;
38     QIOChannel *ioc;
39 } PRManagerHelper;
40 
41 /* Called with lock held.  */
42 static int pr_manager_helper_read(PRManagerHelper *pr_mgr,
43                                   void *buf, int sz, Error **errp)
44 {
45     ssize_t r = qio_channel_read_all(pr_mgr->ioc, buf, sz, errp);
46 
47     if (r < 0) {
48         object_unref(OBJECT(pr_mgr->ioc));
49         pr_mgr->ioc = NULL;
50         return -EINVAL;
51     }
52 
53     return 0;
54 }
55 
56 /* Called with lock held.  */
57 static int pr_manager_helper_write(PRManagerHelper *pr_mgr,
58                                    int fd,
59                                    const void *buf, int sz, Error **errp)
60 {
61     size_t nfds = (fd != -1);
62     while (sz > 0) {
63         struct iovec iov;
64         ssize_t n_written;
65 
66         iov.iov_base = (void *)buf;
67         iov.iov_len = sz;
68         n_written = qio_channel_writev_full(QIO_CHANNEL(pr_mgr->ioc), &iov, 1,
69                                             nfds ? &fd : NULL, nfds, errp);
70 
71         if (n_written <= 0) {
72             assert(n_written != QIO_CHANNEL_ERR_BLOCK);
73             object_unref(OBJECT(pr_mgr->ioc));
74             pr_mgr->ioc = NULL;
75             return n_written < 0 ? -EINVAL : 0;
76         }
77 
78         nfds = 0;
79         buf += n_written;
80         sz -= n_written;
81     }
82 
83     return 0;
84 }
85 
86 /* Called with lock held.  */
87 static int pr_manager_helper_initialize(PRManagerHelper *pr_mgr,
88                                         Error **errp)
89 {
90     char *path = g_strdup(pr_mgr->path);
91     SocketAddress saddr = {
92         .type = SOCKET_ADDRESS_TYPE_UNIX,
93         .u.q_unix.path = path
94     };
95     QIOChannelSocket *sioc = qio_channel_socket_new();
96     Error *local_err = NULL;
97 
98     uint32_t flags;
99     int r;
100 
101     assert(!pr_mgr->ioc);
102     qio_channel_set_name(QIO_CHANNEL(sioc), "pr-manager-helper");
103     qio_channel_socket_connect_sync(sioc,
104                                     &saddr,
105                                     &local_err);
106     g_free(path);
107     if (local_err) {
108         object_unref(OBJECT(sioc));
109         error_propagate(errp, local_err);
110         return -ENOTCONN;
111     }
112 
113     qio_channel_set_delay(QIO_CHANNEL(sioc), false);
114     pr_mgr->ioc = QIO_CHANNEL(sioc);
115 
116     /* A simple feature negotation protocol, even though there is
117      * no optional feature right now.
118      */
119     r = pr_manager_helper_read(pr_mgr, &flags, sizeof(flags), errp);
120     if (r < 0) {
121         goto out_close;
122     }
123 
124     flags = 0;
125     r = pr_manager_helper_write(pr_mgr, -1, &flags, sizeof(flags), errp);
126     if (r < 0) {
127         goto out_close;
128     }
129 
130     return 0;
131 
132 out_close:
133     object_unref(OBJECT(pr_mgr->ioc));
134     pr_mgr->ioc = NULL;
135     return r;
136 }
137 
138 static int pr_manager_helper_run(PRManager *p,
139                                  int fd, struct sg_io_hdr *io_hdr)
140 {
141     PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(p);
142 
143     uint32_t len;
144     PRHelperResponse resp;
145     int ret;
146     int expected_dir;
147     int attempts;
148     uint8_t cdb[PR_HELPER_CDB_SIZE] = { 0 };
149 
150     if (!io_hdr->cmd_len || io_hdr->cmd_len > PR_HELPER_CDB_SIZE) {
151         return -EINVAL;
152     }
153 
154     memcpy(cdb, io_hdr->cmdp, io_hdr->cmd_len);
155     assert(cdb[0] == PERSISTENT_RESERVE_OUT || cdb[0] == PERSISTENT_RESERVE_IN);
156     expected_dir =
157         (cdb[0] == PERSISTENT_RESERVE_OUT ? SG_DXFER_TO_DEV : SG_DXFER_FROM_DEV);
158     if (io_hdr->dxfer_direction != expected_dir) {
159         return -EINVAL;
160     }
161 
162     len = scsi_cdb_xfer(cdb);
163     if (io_hdr->dxfer_len < len || len > PR_HELPER_DATA_SIZE) {
164         return -EINVAL;
165     }
166 
167     qemu_mutex_lock(&pr_mgr->lock);
168 
169     /* Try to reconnect while sending the CDB.  */
170     for (attempts = 0; attempts < PR_MAX_RECONNECT_ATTEMPTS; attempts++) {
171         if (!pr_mgr->ioc) {
172             ret = pr_manager_helper_initialize(pr_mgr, NULL);
173             if (ret < 0) {
174                 qemu_mutex_unlock(&pr_mgr->lock);
175                 g_usleep(G_USEC_PER_SEC);
176                 qemu_mutex_lock(&pr_mgr->lock);
177                 continue;
178             }
179         }
180 
181         ret = pr_manager_helper_write(pr_mgr, fd, cdb, ARRAY_SIZE(cdb), NULL);
182         if (ret >= 0) {
183             break;
184         }
185     }
186     if (ret < 0) {
187         goto out;
188     }
189 
190     /* After sending the CDB, any communications failure causes the
191      * command to fail.  The failure is transient, retrying the command
192      * will invoke pr_manager_helper_initialize again.
193      */
194     if (expected_dir == SG_DXFER_TO_DEV) {
195         io_hdr->resid = io_hdr->dxfer_len - len;
196         ret = pr_manager_helper_write(pr_mgr, -1, io_hdr->dxferp, len, NULL);
197         if (ret < 0) {
198             goto out;
199         }
200     }
201     ret = pr_manager_helper_read(pr_mgr, &resp, sizeof(resp), NULL);
202     if (ret < 0) {
203         goto out;
204     }
205 
206     resp.result = be32_to_cpu(resp.result);
207     resp.sz = be32_to_cpu(resp.sz);
208     if (io_hdr->dxfer_direction == SG_DXFER_FROM_DEV) {
209         assert(resp.sz <= io_hdr->dxfer_len);
210         ret = pr_manager_helper_read(pr_mgr, io_hdr->dxferp, resp.sz, NULL);
211         if (ret < 0) {
212             goto out;
213         }
214         io_hdr->resid = io_hdr->dxfer_len - resp.sz;
215     } else {
216         assert(resp.sz == 0);
217     }
218 
219     io_hdr->status = resp.result;
220     if (resp.result == CHECK_CONDITION) {
221         io_hdr->driver_status = SG_ERR_DRIVER_SENSE;
222         io_hdr->sb_len_wr = MIN(io_hdr->mx_sb_len, PR_HELPER_SENSE_SIZE);
223         memcpy(io_hdr->sbp, resp.sense, io_hdr->sb_len_wr);
224     }
225 
226 out:
227     if (ret < 0) {
228         int sense_len = scsi_build_sense(io_hdr->sbp,
229                                          SENSE_CODE(LUN_COMM_FAILURE));
230         io_hdr->driver_status = SG_ERR_DRIVER_SENSE;
231         io_hdr->sb_len_wr = MIN(io_hdr->mx_sb_len, sense_len);
232         io_hdr->status = CHECK_CONDITION;
233     }
234     qemu_mutex_unlock(&pr_mgr->lock);
235     return ret;
236 }
237 
238 static bool pr_manager_helper_is_connected(PRManager *p)
239 {
240     PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(p);
241     bool result;
242 
243     qemu_mutex_lock(&pr_mgr->lock);
244     result = (pr_mgr->ioc != NULL);
245     qemu_mutex_unlock(&pr_mgr->lock);
246 
247     return result;
248 }
249 
250 static void pr_manager_helper_complete(UserCreatable *uc, Error **errp)
251 {
252     PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(uc);
253 
254     qemu_mutex_lock(&pr_mgr->lock);
255     pr_manager_helper_initialize(pr_mgr, errp);
256     qemu_mutex_unlock(&pr_mgr->lock);
257 }
258 
259 static char *get_path(Object *obj, Error **errp)
260 {
261     PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(obj);
262 
263     return g_strdup(pr_mgr->path);
264 }
265 
266 static void set_path(Object *obj, const char *str, Error **errp)
267 {
268     PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(obj);
269 
270     g_free(pr_mgr->path);
271     pr_mgr->path = g_strdup(str);
272 }
273 
274 static void pr_manager_helper_instance_finalize(Object *obj)
275 {
276     PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(obj);
277 
278     object_unref(OBJECT(pr_mgr->ioc));
279     qemu_mutex_destroy(&pr_mgr->lock);
280 }
281 
282 static void pr_manager_helper_instance_init(Object *obj)
283 {
284     PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(obj);
285 
286     qemu_mutex_init(&pr_mgr->lock);
287 }
288 
289 static void pr_manager_helper_class_init(ObjectClass *klass,
290                                          void *class_data G_GNUC_UNUSED)
291 {
292     PRManagerClass *prmgr_klass = PR_MANAGER_CLASS(klass);
293     UserCreatableClass *uc_klass = USER_CREATABLE_CLASS(klass);
294 
295     object_class_property_add_str(klass, "path", get_path, set_path,
296                                   &error_abort);
297     uc_klass->complete = pr_manager_helper_complete;
298     prmgr_klass->run = pr_manager_helper_run;
299     prmgr_klass->is_connected = pr_manager_helper_is_connected;
300 }
301 
302 static const TypeInfo pr_manager_helper_info = {
303     .parent = TYPE_PR_MANAGER,
304     .name = TYPE_PR_MANAGER_HELPER,
305     .instance_size = sizeof(PRManagerHelper),
306     .instance_init = pr_manager_helper_instance_init,
307     .instance_finalize = pr_manager_helper_instance_finalize,
308     .class_init = pr_manager_helper_class_init,
309 };
310 
311 static void pr_manager_helper_register_types(void)
312 {
313     type_register_static(&pr_manager_helper_info);
314 }
315 
316 type_init(pr_manager_helper_register_types);
317