[Qemu-devel] [PATCH] atapi: Add 'medium ready' to 'medium not ready' transition on cd change

[Amit Shah <amit.shah@redhat.com>]

MMC-5 Table F.1 lists errors that can be thrown for the TEST_UNIT_READY
command.  Going from medium not ready to medium ready states is
communicated by throwing an error.

This adds the missing 'tray opened' event that we fail to report to
guests.  After doing this, older Linux guests properly revalidate a disc
on the change command.  HSM violation errors, which caused Linux guests
to do a soft-reset of the link, also go away:

ata2.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6
sr 1:0:0:0: CDB: Test Unit Ready: 00 00 00 00 00 00
ata2.00: cmd a0/00:00:00:00:00/00:00:00:00:00/a0 tag 0
         res 01/60:00:00:00:00/00:00:00:00:00/a0 Emask 0x3 (HSM violation)
ata2.00: status: { ERR }
ata2: soft resetting link
ata2.00: configured for MWDMA2
ata2: EH complete

Signed-off-by: Amit Shah <amit.shah@redhat.com>
---
 hw/ide/core.c |   20 ++++++++++++++++----
 1 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/hw/ide/core.c b/hw/ide/core.c
index f028ddb..d8c613a 100644
--- a/hw/ide/core.c
+++ b/hw/ide/core.c
@@ -1248,12 +1248,19 @@ static void ide_atapi_cmd(IDEState *s)
         ide_atapi_cmd_check_status(s);
         return;
     }
+    if (bdrv_is_inserted(s->bs) && s->cdrom_changed) {
+        ide_atapi_cmd_error(s, SENSE_NOT_READY, ASC_MEDIUM_NOT_PRESENT);
+
+        s->cdrom_changed = 0;
+        s->sense_key = SENSE_UNIT_ATTENTION;
+        s->asc = ASC_MEDIUM_MAY_HAVE_CHANGED;
+        return;
+    }
     switch(s->io_buffer[0]) {
     case GPCMD_TEST_UNIT_READY:
-        if (bdrv_is_inserted(s->bs) && !s->cdrom_changed) {
+        if (bdrv_is_inserted(s->bs)) {
             ide_atapi_cmd_ok(s);
         } else {
-            s->cdrom_changed = 0;
             ide_atapi_cmd_error(s, SENSE_NOT_READY,
                                 ASC_MEDIUM_NOT_PRESENT);
         }
@@ -1734,8 +1741,13 @@ static void cdrom_change_cb(void *opaque, int reason)
     bdrv_get_geometry(s->bs, &nb_sectors);
     s->nb_sectors = nb_sectors;
 
-    s->sense_key = SENSE_UNIT_ATTENTION;
-    s->asc = ASC_MEDIUM_MAY_HAVE_CHANGED;
+    /*
+     * First indicate to the guest that a CD has been removed.  That's
+     * done on the next command the guest sends us.
+     *
+     * Then we set SENSE_UNIT_ATTENTION, by which the guest will
+     * detect a new CD in the drive.  See ide_atapi_cmd() for details.
+     */
     s->cdrom_changed = 1;
     s->events.new_media = true;
     ide_set_irq(s->bus);
-- 
1.7.4.4