On Thu, 7 Jul 2016 20:20:22 +0530
Bharata B Rao <bhar...@linux.vnet.ibm.com> wrote:
> Add CPUState::stable_cpu_id and use that as instance_id in
> vmstate_register() call.
>
> Introduce has-stable_cpu_id property that allows target machines to
> optionally switch to using stable_cpu_id instead of cpu_index.
If stable_cpu_id is in the [0..max_vcpus) range, then it does not really depend
on the machine type or version. In this case, the property is not needed.
> This will help allow successful migration in cases where holes are
> introduced in cpu_index range after CPU hot removals.
>
> Suggested-by: Igor Mammedov <imamm...@redhat.com>
> Signed-off-by: Bharata B Rao <bhar...@linux.vnet.ibm.com>
> ---
> exec.c | 6 ++++--
> include/qom/cpu.h | 5 +++++
> qom/cpu.c | 6 ++++++
> 3 files changed, 15 insertions(+), 2 deletions(-)
>
> diff --git a/exec.c b/exec.c
> index fb73910..3b36fe5 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -619,12 +619,14 @@ static void cpu_release_index(CPUState *cpu)
> void cpu_vmstate_register(CPUState *cpu)
> {
> CPUClass *cc = CPU_GET_CLASS(cpu);
> + int instance_id = cpu->has_stable_cpu_id ? cpu->stable_cpu_id :
> + cpu->cpu_index;
>
> if (qdev_get_vmsd(DEVICE(cpu)) == NULL) {
> - vmstate_register(NULL, cpu->cpu_index, &vmstate_cpu_common, cpu);
> + vmstate_register(NULL, instance_id, &vmstate_cpu_common, cpu);
> }
> if (cc->vmsd != NULL) {
> - vmstate_register(NULL, cpu->cpu_index, cc->vmsd, cpu);
> + vmstate_register(NULL, instance_id, cc->vmsd, cpu);
> }
> }
>
> diff --git a/include/qom/cpu.h b/include/qom/cpu.h
> index 331386f..527c021 100644
> --- a/include/qom/cpu.h
> +++ b/include/qom/cpu.h
> @@ -273,6 +273,9 @@ struct qemu_work_item {
> * @kvm_fd: vCPU file descriptor for KVM.
> * @work_mutex: Lock to prevent multiple access to queued_work_*.
> * @queued_work_first: First asynchronous work pending.
> + * @stable_cpu_id: Use as instance_id argument in cpu vmstate_register calls
> + * @has_stable_cpu_id: Set to enforce the use of @stable_cpu_id
> + * over cpu_index during vmstate registration.
> *
> * State of one CPU core or thread.
> */
> @@ -360,6 +363,8 @@ struct CPUState {
> (absolute value) offset as small as possible. This reduces code
> size, especially for hosts without large memory offsets. */
> uint32_t tcg_exit_req;
> + int stable_cpu_id;
> + bool has_stable_cpu_id;
> };
>
> QTAILQ_HEAD(CPUTailQ, CPUState);
> diff --git a/qom/cpu.c b/qom/cpu.c
> index 1095ea1..bae1bf7 100644
> --- a/qom/cpu.c
> +++ b/qom/cpu.c
> @@ -363,6 +363,11 @@ static int64_t cpu_common_get_arch_id(CPUState *cpu)
> return cpu->cpu_index;
> }
>
> +static Property cpu_common_properties[] = {
> + DEFINE_PROP_BOOL("has-stable-cpu-id", CPUState, has_stable_cpu_id,
> false),
> + DEFINE_PROP_END_OF_LIST()
> +};
> +
> static void cpu_class_init(ObjectClass *klass, void *data)
> {
> DeviceClass *dc = DEVICE_CLASS(klass);
> @@ -394,6 +399,7 @@ static void cpu_class_init(ObjectClass *klass, void *data)
> * IRQs, adding reset handlers, halting non-first CPUs, ...
> */
> dc->cannot_instantiate_with_device_add_yet = true;
> + dc->props = cpu_common_properties;
> }
>
> static const TypeInfo cpu_type_info = {
