1 /*
2  * Virtio SCSI dataplane
3  *
4  * Copyright Red Hat, Inc. 2014
5  *
6  * Authors:
7  *   Fam Zheng <famz@redhat.com>
8  *
9  * This work is licensed under the terms of the GNU GPL, version 2 or later.
10  * See the COPYING file in the top-level directory.
11  *
12  */
13 
14 #include "qemu/osdep.h"
15 #include "qapi/error.h"
16 #include "hw/virtio/virtio-scsi.h"
17 #include "qemu/error-report.h"
18 #include "sysemu/block-backend.h"
19 #include "hw/scsi/scsi.h"
20 #include "scsi/constants.h"
21 #include "hw/virtio/virtio-bus.h"
22 #include "hw/virtio/virtio-access.h"
23 
24 /* Context: QEMU global mutex held */
25 void virtio_scsi_dataplane_setup(VirtIOSCSI *s, Error **errp)
26 {
27     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
28     VirtIODevice *vdev = VIRTIO_DEVICE(s);
29     BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
30     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
31 
32     if (vs->conf.iothread) {
33         if (!k->set_guest_notifiers || !k->ioeventfd_assign) {
34             error_setg(errp,
35                        "device is incompatible with iothread "
36                        "(transport does not support notifiers)");
37             return;
38         }
39         if (!virtio_device_ioeventfd_enabled(vdev)) {
40             error_setg(errp, "ioeventfd is required for iothread");
41             return;
42         }
43         s->ctx = iothread_get_aio_context(vs->conf.iothread);
44     } else {
45         if (!virtio_device_ioeventfd_enabled(vdev)) {
46             return;
47         }
48         s->ctx = qemu_get_aio_context();
49     }
50 }
51 
52 static bool virtio_scsi_data_plane_handle_cmd(VirtIODevice *vdev,
53                                               VirtQueue *vq)
54 {
55     bool progress;
56     VirtIOSCSI *s = VIRTIO_SCSI(vdev);
57 
58     virtio_scsi_acquire(s);
59     assert(s->ctx && s->dataplane_started);
60     progress = virtio_scsi_handle_cmd_vq(s, vq);
61     virtio_scsi_release(s);
62     return progress;
63 }
64 
65 static bool virtio_scsi_data_plane_handle_ctrl(VirtIODevice *vdev,
66                                                VirtQueue *vq)
67 {
68     bool progress;
69     VirtIOSCSI *s = VIRTIO_SCSI(vdev);
70 
71     virtio_scsi_acquire(s);
72     assert(s->ctx && s->dataplane_started);
73     progress = virtio_scsi_handle_ctrl_vq(s, vq);
74     virtio_scsi_release(s);
75     return progress;
76 }
77 
78 static bool virtio_scsi_data_plane_handle_event(VirtIODevice *vdev,
79                                                 VirtQueue *vq)
80 {
81     bool progress;
82     VirtIOSCSI *s = VIRTIO_SCSI(vdev);
83 
84     virtio_scsi_acquire(s);
85     assert(s->ctx && s->dataplane_started);
86     progress = virtio_scsi_handle_event_vq(s, vq);
87     virtio_scsi_release(s);
88     return progress;
89 }
90 
91 static int virtio_scsi_vring_init(VirtIOSCSI *s, VirtQueue *vq, int n,
92                                   VirtIOHandleAIOOutput fn)
93 {
94     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s)));
95     int rc;
96 
97     /* Set up virtqueue notify */
98     rc = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), n, true);
99     if (rc != 0) {
100         fprintf(stderr, "virtio-scsi: Failed to set host notifier (%d)\n",
101                 rc);
102         s->dataplane_fenced = true;
103         return rc;
104     }
105 
106     virtio_queue_aio_set_host_notifier_handler(vq, s->ctx, fn);
107     return 0;
108 }
109 
110 /* assumes s->ctx held */
111 static void virtio_scsi_clear_aio(VirtIOSCSI *s)
112 {
113     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
114     int i;
115 
116     virtio_queue_aio_set_host_notifier_handler(vs->ctrl_vq, s->ctx, NULL);
117     virtio_queue_aio_set_host_notifier_handler(vs->event_vq, s->ctx, NULL);
118     for (i = 0; i < vs->conf.num_queues; i++) {
119         virtio_queue_aio_set_host_notifier_handler(vs->cmd_vqs[i], s->ctx, NULL);
120     }
121 }
122 
123 /* Context: QEMU global mutex held */
124 int virtio_scsi_dataplane_start(VirtIODevice *vdev)
125 {
126     int i;
127     int rc;
128     BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
129     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
130     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(vdev);
131     VirtIOSCSI *s = VIRTIO_SCSI(vdev);
132 
133     if (s->dataplane_started ||
134         s->dataplane_starting ||
135         s->dataplane_fenced) {
136         return 0;
137     }
138 
139     s->dataplane_starting = true;
140 
141     /* Set up guest notifier (irq) */
142     rc = k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, true);
143     if (rc != 0) {
144         fprintf(stderr, "virtio-scsi: Failed to set guest notifiers (%d), "
145                 "ensure -enable-kvm is set\n", rc);
146         goto fail_guest_notifiers;
147     }
148 
149     aio_context_acquire(s->ctx);
150     rc = virtio_scsi_vring_init(s, vs->ctrl_vq, 0,
151                                 virtio_scsi_data_plane_handle_ctrl);
152     if (rc) {
153         goto fail_vrings;
154     }
155     rc = virtio_scsi_vring_init(s, vs->event_vq, 1,
156                                 virtio_scsi_data_plane_handle_event);
157     if (rc) {
158         goto fail_vrings;
159     }
160     for (i = 0; i < vs->conf.num_queues; i++) {
161         rc = virtio_scsi_vring_init(s, vs->cmd_vqs[i], i + 2,
162                                     virtio_scsi_data_plane_handle_cmd);
163         if (rc) {
164             goto fail_vrings;
165         }
166     }
167 
168     s->dataplane_starting = false;
169     s->dataplane_started = true;
170     aio_context_release(s->ctx);
171     return 0;
172 
173 fail_vrings:
174     virtio_scsi_clear_aio(s);
175     aio_context_release(s->ctx);
176     for (i = 0; i < vs->conf.num_queues + 2; i++) {
177         virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
178     }
179     k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, false);
180 fail_guest_notifiers:
181     s->dataplane_fenced = true;
182     s->dataplane_starting = false;
183     s->dataplane_started = true;
184     return -ENOSYS;
185 }
186 
187 /* Context: QEMU global mutex held */
188 void virtio_scsi_dataplane_stop(VirtIODevice *vdev)
189 {
190     BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
191     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
192     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(vdev);
193     VirtIOSCSI *s = VIRTIO_SCSI(vdev);
194     int i;
195 
196     if (!s->dataplane_started || s->dataplane_stopping) {
197         return;
198     }
199 
200     /* Better luck next time. */
201     if (s->dataplane_fenced) {
202         s->dataplane_fenced = false;
203         s->dataplane_started = false;
204         return;
205     }
206     s->dataplane_stopping = true;
207 
208     aio_context_acquire(s->ctx);
209     virtio_scsi_clear_aio(s);
210     aio_context_release(s->ctx);
211 
212     blk_drain_all(); /* ensure there are no in-flight requests */
213 
214     for (i = 0; i < vs->conf.num_queues + 2; i++) {
215         virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
216     }
217 
218     /* Clean up guest notifier (irq) */
219     k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, false);
220     s->dataplane_stopping = false;
221     s->dataplane_started = false;
222 }
223