> This is a port to ppc of the i386 commit:
> 00f4d64 kvmclock: clock should count only if vm is running
>
> We remove timebase_/pre_save/post_load/ functions,
> and use the VM state change handler to save and restore
> the guest_timebase (on stop and continue).
>
> Time base offset has originally been introduced by commit
> 98a8b52 spapr: Add support for time base offset migration
>
> So while VM is paused, the time is stopped. This allows to have
> the same result with date (based on Time Base Register) and
> hwclock (based on "get-time-of-day" RTAS call).
>
> Moreover in TCG mode, the Time Base is always paused, so this
> patch also adjust the behavior between TCG and KVM.
>
> VM state field "time_of_the_day_ns" is now useless but we keep
> it to be able to migrate to older version of the machine.
>
> As vmstate_ppc_timebase structure (with timebase_pre_save() and
> timebase_post_load() functions) was only used by vmstate_spapr,
> we register the VM state change handler only in ppc_spapr_init().
>
> Signed-off-by: Laurent Vivier <lviv...@redhat.com>
I think you should keep the pre_save handler, otherwise after
migration the timebase register will be off by as long as the
time needed to do the final RAM transfer. See commit 6053a86
("kvmclock: reduce kvmclock difference on migration", 2016-12-22).
Paolo
> ---
> hw/ppc/ppc.c | 76
> ++++++++++++++++++----------------------------------
> hw/ppc/spapr.c | 6 +++++
> hw/ppc/trace-events | 3 ---
> target/ppc/cpu-qom.h | 3 +++
> 4 files changed, 35 insertions(+), 53 deletions(-)
>
> diff --git a/hw/ppc/ppc.c b/hw/ppc/ppc.c
> index 8945869..a839e25 100644
> --- a/hw/ppc/ppc.c
> +++ b/hw/ppc/ppc.c
> @@ -847,10 +847,11 @@ static void cpu_ppc_set_tb_clk (void *opaque, uint32_t
> freq)
> cpu_ppc_store_purr(cpu, 0x0000000000000000ULL);
> }
>
> -static void timebase_pre_save(void *opaque)
> +#if defined(TARGET_PPC64) && defined(CONFIG_KVM)
> +void cpu_ppc_clock_vm_state_change(void *opaque, int running,
> + RunState state)
> {
> PPCTimebase *tb = opaque;
> - uint64_t ticks = cpu_get_host_ticks();
> PowerPCCPU *first_ppc_cpu = POWERPC_CPU(first_cpu);
>
> if (!first_ppc_cpu->env.tb_env) {
> @@ -858,64 +859,39 @@ static void timebase_pre_save(void *opaque)
> return;
> }
>
> - 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 (running) {
> + uint64_t ticks = cpu_get_host_ticks();
> + CPUState *cpu;
> + int64_t tb_offset;
>
> -static int timebase_post_load(void *opaque, int version_id)
> -{
> - PPCTimebase *tb_remote = opaque;
> - CPUState *cpu;
> - PowerPCCPU *first_ppc_cpu = POWERPC_CPU(first_cpu);
> - int64_t tb_off_adj, tb_off, ns_diff;
> - int64_t migration_duration_ns, migration_duration_tb, guest_tb, host_ns;
> - unsigned long freq;
> + tb_offset = tb->guest_timebase - ticks;
>
> - if (!first_ppc_cpu->env.tb_env) {
> - error_report("No timebase object");
> - return -1;
> - }
> -
> - freq = first_ppc_cpu->env.tb_env->tb_freq;
> - /*
> - * Calculate timebase on the destination side of migration.
> - * The destination timebase must be not less than the source timebase.
> - * We try to adjust timebase by downtime if host clocks are not
> - * too much out of sync (1 second for now).
> - */
> - host_ns = qemu_clock_get_ns(QEMU_CLOCK_HOST);
> - ns_diff = MAX(0, host_ns - tb_remote->time_of_the_day_ns);
> - migration_duration_ns = MIN(NANOSECONDS_PER_SECOND, ns_diff);
> - migration_duration_tb = muldiv64(freq, migration_duration_ns,
> - NANOSECONDS_PER_SECOND);
> - guest_tb = tb_remote->guest_timebase + MIN(0, migration_duration_tb);
> -
> - tb_off_adj = guest_tb - cpu_get_host_ticks();
> -
> - tb_off = first_ppc_cpu->env.tb_env->tb_offset;
> - trace_ppc_tb_adjust(tb_off, tb_off_adj, tb_off_adj - tb_off,
> - (tb_off_adj - tb_off) / freq);
> -
> - /* Set new offset to all CPUs */
> - CPU_FOREACH(cpu) {
> - PowerPCCPU *pcpu = POWERPC_CPU(cpu);
> - pcpu->env.tb_env->tb_offset = tb_off_adj;
> + /* Set new offset to all CPUs */
> + CPU_FOREACH(cpu) {
> + PowerPCCPU *pcpu = POWERPC_CPU(cpu);
> + pcpu->env.tb_env->tb_offset = tb_offset;
> + kvm_set_one_reg(cpu, KVM_REG_PPC_TB_OFFSET,
> + &pcpu->env.tb_env->tb_offset);
> + }
> + } else {
> + uint64_t ticks = cpu_get_host_ticks();
> +
> + /* not used anymore, we keep it for compatibility */
> + tb->time_of_the_day_ns = qemu_clock_get_ns(QEMU_CLOCK_HOST);
> + /*
> + * tb_offset is only expected to be changed by QEMU so
> + * there is no need to update it from KVM here
> + */
> + tb->guest_timebase = ticks + first_ppc_cpu->env.tb_env->tb_offset;
> }
> -
> - return 0;
> }
> +#endif
>
> const VMStateDescription vmstate_ppc_timebase = {
> .name = "timebase",
> .version_id = 1,
> .minimum_version_id = 1,
> .minimum_version_id_old = 1,
> - .pre_save = timebase_pre_save,
> - .post_load = timebase_post_load,
> .fields = (VMStateField []) {
> VMSTATE_UINT64(guest_timebase, PPCTimebase),
> VMSTATE_INT64(time_of_the_day_ns, PPCTimebase),
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index a642e66..ee78096 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -2116,6 +2116,12 @@ static void ppc_spapr_init(MachineState *machine)
> qemu_register_reset(spapr_ccs_reset_hook, spapr);
>
> qemu_register_boot_set(spapr_boot_set, spapr);
> +
> + /* to stop and start vmclock */
> + if (kvm_enabled()) {
> + qemu_add_vm_change_state_handler(cpu_ppc_clock_vm_state_change,
> + &spapr->tb);
> + }
> }
>
> static int spapr_kvm_type(const char *vm_type)
> diff --git a/hw/ppc/trace-events b/hw/ppc/trace-events
> index 2297ead..4360c23 100644
> --- a/hw/ppc/trace-events
> +++ b/hw/ppc/trace-events
> @@ -68,9 +68,6 @@ spapr_rtas_ibm_configure_connector_missing_fdt(uint32_t
> index) "DRC index: 0x%"P
> spapr_vio_h_reg_crq(uint64_t reg, uint64_t queue_addr, uint64_t queue_len)
> "CRQ for dev 0x%" PRIx64 " registered at 0x%" PRIx64 "/0x%" PRIx64
> spapr_vio_free_crq(uint32_t reg) "CRQ for dev 0x%" PRIx32 " freed"
>
> -# hw/ppc/ppc.c
> -ppc_tb_adjust(uint64_t offs1, uint64_t offs2, int64_t diff, int64_t seconds)
> "adjusted from 0x%"PRIx64" to 0x%"PRIx64", diff %"PRId64" (%"PRId64"s)"
> -
> # hw/ppc/prep.c
> prep_io_800_writeb(uint32_t addr, uint32_t val) "0x%08" PRIx32 " => 0x%02"
> PRIx32
> prep_io_800_readb(uint32_t addr, uint32_t retval) "0x%08" PRIx32 " <= 0x%02"
> PRIx32
> diff --git a/target/ppc/cpu-qom.h b/target/ppc/cpu-qom.h
> index d46c31a..b7977ba 100644
> --- a/target/ppc/cpu-qom.h
> +++ b/target/ppc/cpu-qom.h
> @@ -214,6 +214,9 @@ extern const struct VMStateDescription
> vmstate_ppc_timebase;
> .flags = VMS_STRUCT, \
> .offset = vmstate_offset_value(_state, _field, PPCTimebase), \
> }
> +
> +void cpu_ppc_clock_vm_state_change(void *opaque, int running,
> + RunState state);
> #endif
>
> #endif
> --
> 2.9.3
>
>
