[PATCH v5 3/5] hpet 'driftfix': add fields to HPETTimer and VMStateDescription

[Ulrich Obergfell <uobergfe@redhat.com>]

The new fields in HPETTimer are covered by a separate VMStateDescription
which is a subsection of 'vmstate_hpet_timer'. They are only migrated if

    -global hpet.driftfix=on

Signed-off-by: Ulrich Obergfell <uobergfe@redhat.com>
---
 hw/hpet.c |   42 ++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 42 insertions(+), 0 deletions(-)

diff --git a/hw/hpet.c b/hw/hpet.c
index 7513065..dba9370 100644
--- a/hw/hpet.c
+++ b/hw/hpet.c
@@ -55,6 +55,19 @@ typedef struct HPETTimer {  /* timers */
     uint8_t wrap_flag;      /* timer pop will indicate wrap for one-shot 32-bit
                              * mode. Next pop will be actual timer expiration.
                              */
+    /* driftfix state */
+    uint64_t prev_period;            /* needed when the guest o/s changes the
+                                      * comparator value */
+    uint64_t ticks_not_accounted;    /* ticks for which no interrupts have been
+                                      * delivered to the guest o/s yet */
+    uint32_t irq_rate;               /* rate at which interrupts are delivered
+                                      * to the guest o/s during one period
+                                      * interval; if rate is greater than 1,
+                                      * additional interrupts are delivered
+                                      * to compensate missed interrupts */
+    uint32_t divisor;                /* needed to determine when the next
+                                      * timer callback should occur while
+                                      * rate is greater than 1 */
 } HPETTimer;
 
 typedef struct HPETState {
@@ -246,6 +259,27 @@ static int hpet_post_load(void *opaque, int version_id)
     return 0;
 }
 
+static bool hpet_timer_driftfix_vmstate_needed(void *opaque)
+{
+    HPETTimer *t = opaque;
+
+    return (t->state->driftfix != 0);
+}
+
+static const VMStateDescription vmstate_hpet_timer_driftfix = {
+    .name = "hpet_timer_driftfix",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .minimum_version_id_old = 1,
+    .fields      = (VMStateField []) {
+        VMSTATE_UINT64(prev_period, HPETTimer),
+        VMSTATE_UINT64(ticks_not_accounted, HPETTimer),
+        VMSTATE_UINT32(irq_rate, HPETTimer),
+        VMSTATE_UINT32(divisor, HPETTimer),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
 static const VMStateDescription vmstate_hpet_timer = {
     .name = "hpet_timer",
     .version_id = 1,
@@ -260,6 +294,14 @@ static const VMStateDescription vmstate_hpet_timer = {
         VMSTATE_UINT8(wrap_flag, HPETTimer),
         VMSTATE_TIMER(qemu_timer, HPETTimer),
         VMSTATE_END_OF_LIST()
+    },
+    .subsections = (VMStateSubsection []) {
+        {
+            .vmsd = &vmstate_hpet_timer_driftfix,
+            .needed = hpet_timer_driftfix_vmstate_needed,
+        }, {
+            /* empty */
+        }
     }
 };
 
-- 
1.6.2.5