s390x/tcg: properly implement the TOD

Right now, each CPU has its own TOD. Especially, the TOD will differ
based on creation time of a CPU - e.g. when hotplugging a CPU the times
will differ quite a lot, resulting in stall warnings in the guest.

Let's use a single TOD by implementing our new TOD device. Prepare it
for TOD-clock epoch extension.

Most importantly, whenever we set the TOD, we have to update the CKC
timer.

Introduce "tcg_s390x.h" just like "kvm_s390x.h" for tcg specific
function declarations that should not go into cpu.h.

Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20180627134410.4901-6-david@redhat.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>

2 files changed, 53 insertions, 4 deletions

diff --git a/hw/s390x/tod-qemu.c b/hw/s390x/tod-qemu.c
index 03ea1ce..59c015c 100644
--- a/hw/s390x/tod-qemu.c
+++ b/hw/s390x/tod-qemu.c
@@ -11,19 +11,43 @@
 #include "qemu/osdep.h"
 #include "qapi/error.h"
 #include "hw/s390x/tod.h"
+#include "qemu/timer.h"
+#include "qemu/cutils.h"
+#include "cpu.h"
+#include "tcg_s390x.h"
 
 static void qemu_s390_tod_get(const S390TODState *td, S390TOD *tod,
                               Error **errp)
 {
-    /* FIXME */
-    tod->high = 0;
-    tod->low = 0;
+    *tod = td->base;
+
+    tod->low += time2tod(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL));
+    if (tod->low < td->base.low) {
+        tod->high++;
+    }
 }
 
 static void qemu_s390_tod_set(S390TODState *td, const S390TOD *tod,
                               Error **errp)
 {
-    /* FIXME */
+    CPUState *cpu;
+
+    td->base = *tod;
+
+    td->base.low -= time2tod(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL));
+    if (td->base.low > tod->low) {
+        td->base.high--;
+    }
+
+    /*
+     * The TOD has been changed and we have to recalculate the CKC values
+     * for all CPUs. We do this asynchronously, as "SET CLOCK should be
+     * issued only while all other activity on all CPUs .. has been
+     * suspended".
+     */
+    CPU_FOREACH(cpu) {
+        async_run_on_cpu(cpu, tcg_s390_tod_updated, RUN_ON_CPU_NULL);
+    }
 }
 
 static void qemu_s390_tod_class_init(ObjectClass *oc, void *data)
@@ -34,10 +58,24 @@ static void qemu_s390_tod_class_init(ObjectClass *oc, void *data)
     tdc->set = qemu_s390_tod_set;
 }
 
+static void qemu_s390_tod_init(Object *obj)
+{
+    S390TODState *td = S390_TOD(obj);
+    struct tm tm;
+
+    qemu_get_timedate(&tm, 0);
+    td->base.high = 0;
+    td->base.low = TOD_UNIX_EPOCH + (time2tod(mktimegm(&tm)) * 1000000000ULL);
+    if (td->base.low < TOD_UNIX_EPOCH) {
+        td->base.high += 1;
+    }
+}
+
 static TypeInfo qemu_s390_tod_info = {
     .name = TYPE_QEMU_S390_TOD,
     .parent = TYPE_S390_TOD,
     .instance_size = sizeof(S390TODState),
+    .instance_init = qemu_s390_tod_init,
     .class_init = qemu_s390_tod_class_init,
     .class_size = sizeof(S390TODClass),
 };
diff --git a/hw/s390x/tod.c b/hw/s390x/tod.c
index 0501aff..1c63f41 100644
--- a/hw/s390x/tod.c
+++ b/hw/s390x/tod.c
@@ -30,6 +30,17 @@ void s390_init_tod(void)
     qdev_init_nofail(DEVICE(obj));
 }
 
+S390TODState *s390_get_todstate(void)
+{
+    static S390TODState *ts;
+
+    if (!ts) {
+        ts = S390_TOD(object_resolve_path_type("", TYPE_S390_TOD, NULL));
+    }
+
+    return ts;
+}
+
 #define S390_TOD_CLOCK_VALUE_MISSING    0x00
 #define S390_TOD_CLOCK_VALUE_PRESENT    0x01