Re: [Qemu-devel] latest rc: virtio-blk hangs forever after migration

["Marcin Gibuła" <m.gibula@beyond.pl>]

> Andrey,
>
> Can you please provide instructions on how to create reproducible
> environment?
>
> The following patch is equivalent to the original patch, for
> the purposes of fixing the kvmclock problem.
>
> Perhaps it becomes easier to spot the reason for the hang you are
> experiencing.

Marcelo,

the original reason for patch adding cpu_synchronize_all_states() there 
was because this bug affected non-migration operations as well - 
http://lists.gnu.org/archive/html/qemu-devel/2014-06/msg00472.html.

Won't moving it only to migration code break these things again?

>
> diff --git a/hw/i386/kvm/clock.c b/hw/i386/kvm/clock.c
> index 272a88a..feb5fc5 100644
> --- a/hw/i386/kvm/clock.c
> +++ b/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));
> diff --git a/migration.c b/migration.c
> index 8d675b3..34f2325 100644
> --- a/migration.c
> +++ b/migration.c
> @@ -608,6 +608,7 @@ static void *migration_thread(void *opaque)
>                   qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER);
>                   old_vm_running = runstate_is_running();
>
> +                cpu_synchronize_all_states();
>                   ret = vm_stop_force_state(RUN_STATE_FINISH_MIGRATE);
>                   if (ret >= 0) {
>                       qemu_file_set_rate_limit(s->file, INT64_MAX);
>


-- 
mg