pseries: Move rtc_offset into RTC device's state structure

The initial creation of the PAPR RTC qdev class left a wart - the rtc's
offset was left in the sPAPREnvironment structure, accessed via a global.

This patch moves it into the RTC device's own state structure, were it
belongs.  This requires a small change to the migration stream format.  In
order to handle incoming streams from older versions, we also need to
retain the rtc_offset field in the sPAPREnvironment structure, so that it
can be loaded into via the vmsd, then pushed into the RTC device.

Since we're changing the migration format, this also takes the opportunity
to:

  * Change the rtc offset from a value in seconds to a value in
    nanoseconds, allowing nanosecond offsets between host and guest
    rtc time, if desired.

  * Remove both the already unused "next_irq" field and now unused
    "rtc_offset" field from the new version of the spapr migration
    stream

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Alexander Graf <agraf@suse.de>

1 files changed, 27 insertions, 3 deletions

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 1908988dbc..6e8248d01e 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -1019,15 +1019,39 @@ static int spapr_vga_init(PCIBus *pci_bus)
     }
 }
 
+static int spapr_post_load(void *opaque, int version_id)
+{
+    sPAPREnvironment *spapr = (sPAPREnvironment *)opaque;
+    int err = 0;
+
+    /* In earlier versions, there was no seperate qdev for the PAPR
+     * RTC, so the RTC offset was stored directly in sPAPREnvironment.
+     * So when migrating from those versions, poke the incoming offset
+     * value into the RTC device */
+    if (version_id < 3) {
+        err = spapr_rtc_import_offset(spapr->rtc, spapr->rtc_offset);
+    }
+
+    return err;
+}
+
+static bool version_before_3(void *opaque, int version_id)
+{
+    return version_id < 3;
+}
+
 static const VMStateDescription vmstate_spapr = {
     .name = "spapr",
-    .version_id = 2,
+    .version_id = 3,
     .minimum_version_id = 1,
+    .post_load = spapr_post_load,
     .fields = (VMStateField[]) {
-        VMSTATE_UNUSED(4), /* used to be @next_irq */
+        /* used to be @next_irq */
+        VMSTATE_UNUSED_BUFFER(version_before_3, 0, 4),
 
         /* RTC offset */
-        VMSTATE_UINT64(rtc_offset, sPAPREnvironment),
+        VMSTATE_UINT64_TEST(rtc_offset, sPAPREnvironment, version_before_3),
+
         VMSTATE_PPC_TIMEBASE_V(tb, sPAPREnvironment, 2),
         VMSTATE_END_OF_LIST()
     },