Re: [Qemu-devel] [PATCH v3 1/3] target-i386: add a subsection for migrating vcpu's TSC rate

[Eduardo Habkost <ehabkost@redhat.com>]

On Mon, Nov 02, 2015 at 05:26:41PM +0800, Haozhong Zhang wrote:
> A new subsection 'vmstate_tsc_khz' is added to migrate vcpu's TSC
> rate. For the backwards compatibility, this subsection is not migrated
> on pc-*-2.4 and older machine types.
> 
> Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com>
> ---
>  hw/i386/pc.c          |  1 +
>  hw/i386/pc_piix.c     |  1 +
>  hw/i386/pc_q35.c      |  1 +
>  include/hw/i386/pc.h  |  1 +
>  target-i386/cpu.h     |  1 +
>  target-i386/machine.c | 21 +++++++++++++++++++++
>  6 files changed, 26 insertions(+)
> 
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index 0cb8afd..2f2fc93 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -1952,6 +1952,7 @@ static void pc_machine_class_init(ObjectClass *oc, void *data)
>      HotplugHandlerClass *hc = HOTPLUG_HANDLER_CLASS(oc);
>  
>      pcmc->get_hotplug_handler = mc->get_hotplug_handler;
> +    pcmc->save_tsc_khz = true;
>      mc->get_hotplug_handler = pc_get_hotpug_handler;
>      mc->cpu_index_to_socket_id = pc_cpu_index_to_socket_id;
>      mc->default_boot_order = "cad";
> diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
> index 393dcc4..fc71321 100644
> --- a/hw/i386/pc_piix.c
> +++ b/hw/i386/pc_piix.c
> @@ -487,6 +487,7 @@ static void pc_i440fx_2_4_machine_options(MachineClass *m)
>      m->alias = NULL;
>      m->is_default = 0;
>      pcmc->broken_reserved_end = true;
> +    pcmc->save_tsc_khz = false;
>      SET_MACHINE_COMPAT(m, PC_COMPAT_2_4);
>  }
>  
> diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
> index 2f8f396..858ed69 100644
> --- a/hw/i386/pc_q35.c
> +++ b/hw/i386/pc_q35.c
> @@ -385,6 +385,7 @@ static void pc_q35_2_4_machine_options(MachineClass *m)
>      pc_q35_2_5_machine_options(m);
>      m->alias = NULL;
>      pcmc->broken_reserved_end = true;
> +    pcmc->save_tsc_khz = false;

I had suggested the PCMachineClass field, but now I've been thinking:
all other fields related to tsc_khz are in X86CPU, so I believe this
belongs to X86CPU too. It could be a simple X86CPU property set by
PC_COMPAT_2_4.

-- 
Eduardo