Revert "kvmclock: Ensure proper env->tsc value for kvmclock_current_nsec calculation"

This reverts commit 9b178682.

This patch fixed a hang introduced by commit a096b3a6 (kvmclock: Ensure
time in migration never goes backward, 2014-05-16), but it causes
a regression in migration whose cause is not quite clear.

Because of this, I'm choosing to revert both patches.  This trades a
2.1 regression for a bug that's been there forever.

Cc: agraf@suse.de
Cc: mtosatti@redhat.com
Cc: qemu-stable@nongnu.org
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

hw/i386/kvm/clock.c

@@ -17,7 +17,6 @@
 #include "qemu/host-utils.h"
 #include "sysemu/sysemu.h"
 #include "sysemu/kvm.h"
-#include "sysemu/cpus.h"
 #include "hw/sysbus.h"
 #include "hw/kvm/clock.h"
 
@@ -66,7 +65,6 @@ static uint64_t kvmclock_current_nsec(KVMClockState *s)
 
     cpu_physical_memory_read(kvmclock_struct_pa, &time, sizeof(time));
 
-    assert(time.tsc_timestamp <= migration_tsc);
     delta = migration_tsc - time.tsc_timestamp;
     if (time.tsc_shift < 0) {
         delta >>= -time.tsc_shift;
@@ -125,8 +123,6 @@ static void kvmclock_vm_state_change(void *opaque, int running,
         if (s->clock_valid) {
             return;
         }
-
-        cpu_synchronize_all_states();
         ret = kvm_vm_ioctl(kvm_state, KVM_GET_CLOCK, &data);
         if (ret < 0) {
             fprintf(stderr, "KVM_GET_CLOCK failed: %s\n", strerror(ret));