[Qemu-devel] [PATCH 2/3] ppc: add support for timebase migration on non-PPC hosts

[Mark Cave-Ayland]

This patch provides support for migration of the PPC guest timebase on non-PPC
host architectures (i.e those using QEMU's virtual emulated timebase).

Signed-off-by: Mark Cave-Ayland <mark.cave-ayl...@ilande.co.uk>
---
 hw/ppc/ppc.c |   33 +++++++++++++++++++++++++++------
 1 file changed, 27 insertions(+), 6 deletions(-)

diff --git a/hw/ppc/ppc.c b/hw/ppc/ppc.c
index 19f4570..9b80c1d 100644
--- a/hw/ppc/ppc.c
+++ b/hw/ppc/ppc.c
@@ -832,6 +832,15 @@ static void cpu_ppc_set_tb_clk (void *opaque, uint32_t 
freq)
     cpu_ppc_store_purr(cpu, 0x0000000000000000ULL);
 }
 
+static int host_cpu_is_ppc(void)
+{
+#if defined(_ARCH_PPC)
+    return -1;
+#else
+    return 0;
+#endif
+}
+
 static void timebase_pre_save(void *opaque)
 {
     PPCTimebase *tb = opaque;
@@ -844,11 +853,16 @@ static void timebase_pre_save(void *opaque)
     }
 
     tb->time_of_the_day_ns = qemu_clock_get_ns(QEMU_CLOCK_HOST);
-    /*
-     * tb_offset is only expected to be changed by migration so
-     * there is no need to update it from KVM here
-     */
-    tb->guest_timebase = ticks + first_ppc_cpu->env.tb_env->tb_offset;
+
+    if (host_cpu_is_ppc()) {
+        /*
+         * tb_offset is only expected to be changed by migration so
+         * there is no need to update it from KVM here
+         */
+        tb->guest_timebase = ticks + first_ppc_cpu->env.tb_env->tb_offset;
+    } else {
+        tb->guest_timebase = cpu_ppc_load_tbl(&first_ppc_cpu->env);
+    }
 }
 
 static int timebase_post_load(void *opaque, int version_id)
@@ -879,7 +893,14 @@ static int timebase_post_load(void *opaque, int version_id)
                                      NANOSECONDS_PER_SECOND);
     guest_tb = tb_remote->guest_timebase + migration_duration_tb;
 
-    tb_off_adj = guest_tb - cpu_get_host_ticks();
+    if (host_cpu_is_ppc()) {
+        /* Hardware timebase */
+        tb_off_adj = guest_tb - cpu_get_host_ticks();
+    } else {
+        /* Software timebase */
+        tb_off_adj = guest_tb - muldiv64(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL),
+                                         freq, get_ticks_per_sec());
+    }
 
     tb_off = first_ppc_cpu->env.tb_env->tb_offset;
     trace_ppc_tb_adjust(tb_off, tb_off_adj, tb_off_adj - tb_off,
-- 
1.7.10.4