scsi-disk: report media changed via unit attention sense codes

Building on the previous patch, this one adds a media change callback
to scsi-disk.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

hw/scsi-bus.c

@@ -847,6 +847,11 @@ const struct SCSISense sense_code_RESET = {
     .key = UNIT_ATTENTION, .asc = 0x29, .ascq = 0x00
 };
 
+/* Unit attention, No medium */
+const struct SCSISense sense_code_UNIT_ATTENTION_NO_MEDIUM = {
+    .key = UNIT_ATTENTION, .asc = 0x3a, .ascq = 0x00
+};
+
 /* Unit attention, Medium may have changed */
 const struct SCSISense sense_code_MEDIUM_CHANGED = {
     .key = UNIT_ATTENTION, .asc = 0x28, .ascq = 0x00

hw/scsi-disk.c

@@ -71,6 +71,7 @@ struct SCSIDiskState
     int cluster_size;
     uint32_t removable;
     uint64_t max_lba;
+    bool media_changed;
     QEMUBH *bh;
     char *version;
     char *serial;
@@ -1198,7 +1199,21 @@ static void scsi_destroy(SCSIDevice *dev)
 
 static void scsi_cd_change_media_cb(void *opaque, bool load)
 {
-    ((SCSIDiskState *)opaque)->tray_open = !load;
+    SCSIDiskState *s = opaque;
+
+    /*
+     * When a CD gets changed, we have to report an ejected state and
+     * then a loaded state to guests so that they detect tray
+     * open/close and media change events.  Guests that do not use
+     * GET_EVENT_STATUS_NOTIFICATION to detect such tray open/close
+     * states rely on this behavior.
+     *
+     * media_changed governs the state machine used for unit attention
+     * report.  media_event is used by GET EVENT STATUS NOTIFICATION.
+     */
+    s->media_changed = load;
+    s->tray_open = !load;
+    s->qdev.unit_attention = SENSE_CODE(UNIT_ATTENTION_NO_MEDIUM);
 }
 
 static bool scsi_cd_is_tray_open(void *opaque)
@@ -1217,6 +1232,15 @@ static const BlockDevOps scsi_cd_block_ops = {
     .is_medium_locked = scsi_cd_is_medium_locked,
 };
 
+static void scsi_disk_unit_attention_reported(SCSIDevice *dev)
+{
+    SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, dev);
+    if (s->media_changed) {
+        s->media_changed = false;
+        s->qdev.unit_attention = SENSE_CODE(MEDIUM_CHANGED);
+    }
+}
+
 static int scsi_initfn(SCSIDevice *dev, uint8_t scsi_type)
 {
     SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, dev);
@@ -1329,6 +1353,7 @@ static SCSIDeviceInfo scsi_disk_info[] = {
         .init         = scsi_hd_initfn,
         .destroy      = scsi_destroy,
         .alloc_req    = scsi_new_request,
+        .unit_attention_reported = scsi_disk_unit_attention_reported,
         .qdev.props   = (Property[]) {
             DEFINE_SCSI_DISK_PROPERTIES(),
             DEFINE_PROP_BIT("removable", SCSIDiskState, removable, 0, false),
@@ -1343,6 +1368,7 @@ static SCSIDeviceInfo scsi_disk_info[] = {
         .init         = scsi_cd_initfn,
         .destroy      = scsi_destroy,
         .alloc_req    = scsi_new_request,
+        .unit_attention_reported = scsi_disk_unit_attention_reported,
         .qdev.props   = (Property[]) {
             DEFINE_SCSI_DISK_PROPERTIES(),
             DEFINE_PROP_END_OF_LIST(),
@@ -1356,6 +1382,7 @@ static SCSIDeviceInfo scsi_disk_info[] = {
         .init         = scsi_disk_initfn,
         .destroy      = scsi_destroy,
         .alloc_req    = scsi_new_request,
+        .unit_attention_reported = scsi_disk_unit_attention_reported,
         .qdev.props   = (Property[]) {
             DEFINE_SCSI_DISK_PROPERTIES(),
             DEFINE_PROP_BIT("removable", SCSIDiskState, removable, 0, false),

hw/scsi.h

@@ -161,6 +161,8 @@ extern const struct SCSISense sense_code_IO_ERROR;
 extern const struct SCSISense sense_code_I_T_NEXUS_LOSS;
 /* Command aborted, Logical Unit failure */
 extern const struct SCSISense sense_code_LUN_FAILURE;
+/* LUN not ready, Medium not present */
+extern const struct SCSISense sense_code_UNIT_ATTENTION_NO_MEDIUM;
 /* Unit attention, Power on, reset or bus device reset occurred */
 extern const struct SCSISense sense_code_RESET;
 /* Unit attention, Medium may have changed*/