[PATCH 09/15] hw/ide: migrate the power-on defaults revert flag

From: Denis V. Lunev <[email protected]>

SET FEATURES 0xCC asks for the next reset to revert to the power-on
defaults, and 0x66 cancels that; ide_reset() restores the default CHS
translation only when the flag is set. It was in no VMStateDescription, so
it always arrived cleared.

That was invisible while the destination had the default translation
anyway. Now that the translation is migrated, the flag decides how long it
stays in effect: without it, a reset after the migration reverts the
geometry on the source and keeps it on the destination.

Send it only alongside a translation the guest replaced. On the default
geometry it reverts to what is already in effect, so such a guest need not
lose its migration to an older QEMU over a subsection that changes
nothing.

Cc: John Snow <[email protected]>
Cc: Peter Maydell <[email protected]>
Fixes: 176e4961bb33 ("hw/ide/core.c: Implement ATA INITIALIZE_DEVICE_PARAMETERS command")
Signed-off-by: Denis V. Lunev <[email protected]>
---
 hw/ide/core.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/hw/ide/core.c b/hw/ide/core.c
index ab8c23e5b9..c330508128 100644
--- a/hw/ide/core.c
+++ b/hw/ide/core.c
@@ -2988,6 +2988,25 @@ static const VMStateDescription vmstate_ide_drive_chs_translation = {
     }
 };
 
+static bool ide_reset_reverts_needed(void *opaque)
+{
+    IDEState *s = opaque;
+
+    return s->reset_reverts && ide_chs_translation_needed(opaque);
+}
+
+/* The flag decides nothing on the default geometry, so it travels with one */
+static const VMStateDescription vmstate_ide_drive_reset_reverts = {
+    .name = "ide_drive/reset_reverts",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .needed = ide_reset_reverts_needed,
+    .fields = (const VMStateField[]) {
+        VMSTATE_BOOL(reset_reverts, IDEState),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
 static const VMStateDescription vmstate_ide_tray_state = {
     .name = "ide_drive/tray_state",
     .version_id = 1,
@@ -3052,6 +3071,7 @@ const VMStateDescription vmstate_ide_drive = {
     .subsections = (const VMStateDescription * const []) {
         &vmstate_ide_drive_pio_state,
         &vmstate_ide_drive_chs_translation,
+        &vmstate_ide_drive_reset_reverts,
         &vmstate_ide_tray_state,
         &vmstate_ide_atapi_gesn_state,
         NULL
-- 
2.53.0