atapi: GESN: implement 'media' subcommand

Implement the 'media' sub-command of the GET_EVENT_STATUS_NOTIFICATION
command.  This helps us report tray open, tray closed, no media, media
present states to the guest.

Newer Linux kernels (2.6.38+) rely on this command to revalidate discs
after media change.

This patch also sends out tray open/closed status to the guest driver
when requested e.g. via the CDROM_DRIVE_STATUS ioctl (thanks Markus).
Without such notification, the guest and qemu's tray open/close status
was frequently out of sync, causing installers like Anaconda detecting
no disc instead of tray open, confusing them terribly.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Acked-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

hw/ide/core.c

@@ -1084,6 +1084,48 @@ static int ide_dvd_read_structure(IDEState *s, int format,
     }
 }
 
+static unsigned int event_status_media(IDEState *s,
+                                       uint8_t *buf)
+{
+    enum media_event_code {
+        MEC_NO_CHANGE = 0,       /* Status unchanged */
+        MEC_EJECT_REQUESTED,     /* received a request from user to eject */
+        MEC_NEW_MEDIA,           /* new media inserted and ready for access */
+        MEC_MEDIA_REMOVAL,       /* only for media changers */
+        MEC_MEDIA_CHANGED,       /* only for media changers */
+        MEC_BG_FORMAT_COMPLETED, /* MRW or DVD+RW b/g format completed */
+        MEC_BG_FORMAT_RESTARTED, /* MRW or DVD+RW b/g format restarted */
+    };
+    enum media_status {
+        MS_TRAY_OPEN = 1,
+        MS_MEDIA_PRESENT = 2,
+    };
+    uint8_t event_code, media_status;
+
+    media_status = 0;
+    if (s->bs->tray_open) {
+        media_status = MS_TRAY_OPEN;
+    } else if (bdrv_is_inserted(s->bs)) {
+        media_status = MS_MEDIA_PRESENT;
+    }
+
+    /* Event notification descriptor */
+    event_code = MEC_NO_CHANGE;
+    if (media_status != MS_TRAY_OPEN && s->events.new_media) {
+        event_code = MEC_NEW_MEDIA;
+        s->events.new_media = false;
+    }
+
+    buf[4] = event_code;
+    buf[5] = media_status;
+
+    /* These fields are reserved, just clear them. */
+    buf[6] = 0;
+    buf[7] = 0;
+
+    return 8; /* We wrote to 4 extra bytes from the header */
+}
+
 static void handle_get_event_status_notification(IDEState *s,
                                                  uint8_t *buf,
                                                  const uint8_t *packet)
@@ -1104,6 +1146,26 @@ static void handle_get_event_status_notification(IDEState *s,
         uint8_t supported_events;
     } __attribute((packed)) *gesn_event_header;
 
+    enum notification_class_request_type {
+        NCR_RESERVED1 = 1 << 0,
+        NCR_OPERATIONAL_CHANGE = 1 << 1,
+        NCR_POWER_MANAGEMENT = 1 << 2,
+        NCR_EXTERNAL_REQUEST = 1 << 3,
+        NCR_MEDIA = 1 << 4,
+        NCR_MULTI_HOST = 1 << 5,
+        NCR_DEVICE_BUSY = 1 << 6,
+        NCR_RESERVED2 = 1 << 7,
+    };
+    enum event_notification_class_field {
+        ENC_NO_EVENTS = 0,
+        ENC_OPERATIONAL_CHANGE,
+        ENC_POWER_MANAGEMENT,
+        ENC_EXTERNAL_REQUEST,
+        ENC_MEDIA,
+        ENC_MULTIPLE_HOSTS,
+        ENC_DEVICE_BUSY,
+        ENC_RESERVED,
+    };
     unsigned int max_len, used_len;
 
     gesn_cdb = (void *)packet;
@@ -1121,12 +1183,32 @@ static void handle_get_event_status_notification(IDEState *s,
 
     /* polling mode operation */
 
-    /* We don't support any event class (yet). */
-    gesn_event_header->supported_events = 0;
+    /*
+     * These are the supported events.
+     *
+     * We currently only support requests of the 'media' type.
+     */
+    gesn_event_header->supported_events = NCR_MEDIA;
 
-    gesn_event_header->notification_class = 0x80; /* No event available */
-    used_len = sizeof(*gesn_event_header);
+    /*
+     * We use |= below to set the class field; other bits in this byte
+     * are reserved now but this is useful to do if we have to use the
+     * reserved fields later.
+     */
+    gesn_event_header->notification_class = 0;
 
+    /*
+     * Responses to requests are to be based on request priority.  The
+     * notification_class_request_type enum above specifies the
+     * priority: upper elements are higher prio than lower ones.
+     */
+    if (gesn_cdb->class & NCR_MEDIA) {
+        gesn_event_header->notification_class |= ENC_MEDIA;
+        used_len = event_status_media(s, buf);
+    } else {
+        gesn_event_header->notification_class = 0x80; /* No event available */
+        used_len = sizeof(*gesn_event_header);
+    }
     gesn_event_header->len = cpu_to_be16(used_len
                                          - sizeof(*gesn_event_header));
     ide_atapi_cmd_reply(s, used_len, max_len);
@@ -1655,6 +1737,7 @@ static void cdrom_change_cb(void *opaque, int reason)
     s->sense_key = SENSE_UNIT_ATTENTION;
     s->asc = ASC_MEDIUM_MAY_HAVE_CHANGED;
     s->cdrom_changed = 1;
+    s->events.new_media = true;
     ide_set_irq(s->bus);
 }
 
@@ -2799,6 +2882,25 @@ static bool ide_drive_pio_state_needed(void *opaque)
     return (s->status & DRQ_STAT) != 0;
 }
 
+static bool ide_atapi_gesn_needed(void *opaque)
+{
+    IDEState *s = opaque;
+
+    return s->events.new_media || s->events.eject_request;
+}
+
+/* Fields for GET_EVENT_STATUS_NOTIFICATION ATAPI command */
+const VMStateDescription vmstate_ide_atapi_gesn_state = {
+    .name ="ide_drive/atapi/gesn_state",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .minimum_version_id_old = 1,
+    .fields = (VMStateField []) {
+        VMSTATE_BOOL(events.new_media, IDEState),
+        VMSTATE_BOOL(events.eject_request, IDEState),
+    }
+};
+
 const VMStateDescription vmstate_ide_drive_pio_state = {
     .name = "ide_drive/pio_state",
     .version_id = 1,
@@ -2852,6 +2954,9 @@ const VMStateDescription vmstate_ide_drive = {
         {
             .vmsd = &vmstate_ide_drive_pio_state,
             .needed = ide_drive_pio_state_needed,
+        }, {
+            .vmsd = &vmstate_ide_atapi_gesn_state,
+            .needed = ide_atapi_gesn_needed,
         }, {
             /* empty */
         }

hw/ide/internal.h

@@ -373,6 +373,11 @@ typedef int DMAFunc(IDEDMA *);
 typedef int DMAIntFunc(IDEDMA *, int);
 typedef void DMARestartFunc(void *, int, int);
 
+struct unreported_events {
+    bool eject_request;
+    bool new_media;
+};
+
 /* NOTE: IDEState represents in fact one drive */
 struct IDEState {
     IDEBus *bus;
@@ -408,6 +413,7 @@ struct IDEState {
     BlockDriverState *bs;
     char version[9];
     /* ATAPI specific */
+    struct unreported_events events;
     uint8_t sense_key;
     uint8_t asc;
     uint8_t cdrom_changed;