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Date: Tue, 29 Sep 2015 20:00:13 +0100
From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Message-ID: <20150929190013.GO3810@work-vm>
References: <1443418711-24106-1-git-send-email-haozhong.zhang@intel.com>
	<1443418711-24106-2-git-send-email-haozhong.zhang@intel.com>
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In-Reply-To: <1443418711-24106-2-git-send-email-haozhong.zhang@intel.com>
Subject: Re: [Qemu-devel] [PATCH 1/3] target-i386: add a subsection of
 vcpu's TSC rate in vmstate_x86_cpu
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To: Haozhong Zhang <haozhong.zhang@intel.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>, kvm@vger.kernel.org, Marcelo Tosatti <mtosatti@redhat.com>, qemu-devel@nongnu.org, Paolo Bonzini <pbonzini@redhat.com>, Richard Henderson <rth@twiddle.net>

* Haozhong Zhang (haozhong.zhang@intel.com) wrote:
> The newly added subsection 'vmstate_tsc_khz' in this patch results in
> vcpu's TSC rate being saved on the source machine and loaded on the
> target machine during the migration.
> 
> Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com>

Hi,
  I'd appreciate it if you could tie this to only do it on newer
machine types; that way it won't break back migration.

Dave

> ---
>  target-i386/machine.c | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
> 
> diff --git a/target-i386/machine.c b/target-i386/machine.c
> index 9fa0563..80108a3 100644
> --- a/target-i386/machine.c
> +++ b/target-i386/machine.c
> @@ -752,6 +752,25 @@ static const VMStateDescription vmstate_xss = {
>      }
>  };
>  
> +static bool tsc_khz_needed(void *opaque)
> +{
> +    X86CPU *cpu = opaque;
> +    CPUX86State *env = &cpu->env;
> +
> +    return env->tsc_khz != 0;
> +}
> +
> +static const VMStateDescription vmstate_tsc_khz = {
> +    .name = "cpu/tsc_khz",
> +    .version_id = 1,
> +    .minimum_version_id = 1,
> +    .needed = tsc_khz_needed,
> +    .fields = (VMStateField[]) {
> +        VMSTATE_INT64(env.tsc_khz, X86CPU),
> +        VMSTATE_END_OF_LIST()
> +    }
> +};
> +
>  VMStateDescription vmstate_x86_cpu = {
>      .name = "cpu",
>      .version_id = 12,
> @@ -871,6 +890,7 @@ VMStateDescription vmstate_x86_cpu = {
>          &vmstate_msr_hyperv_crash,
>          &vmstate_avx512,
>          &vmstate_xss,
> +        &vmstate_tsc_khz,
>          NULL
>      }
>  };
> -- 
> 2.4.8
> 
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK