Re: [RFC] Do clock adjustments over migration

[Marcelo Tosatti <mtosatti@redhat.com>]

On Thu, Oct 15, 2009 at 01:15:25PM -0400, Glauber Costa wrote:
> Hey,
> 
> This patch is a proposal only. Among other things, it relies on a patch
> Juan is yet to send, and I also would want to give it a bit more testing.
> It shows my indented use of the new ioctl interface I've been proposing.
> 
> First of all, we have to save the kvmclock msrs. This is per-cpu, and we
> were failing to do it so far.
> 
> The ioctls are issued in pre-save and post-load sections of a new vmstate
> handler. I am not doing it in the cpu vmstate handler, because this has to
> be done once per VM, not cpu. What I basically do is to grab the time
> from GET ioctl, pass on through migration, and then do a SET on the other
> side. Should be straighforward.
> 
> Please let me hear your thoughts. And don't get me started with this
> "you can't hear thoughts" thing!
> 
> Signed-off-by: Glauber Costa <glommer@redhat.com>
> ---
>  kvm/include/linux/kvm.h |    9 +++++++++
>  qemu-kvm-x86.c          |    6 ++++++
>  qemu-kvm.c              |   29 +++++++++++++++++++++++++++++
>  target-i386/cpu.h       |    3 ++-
>  target-i386/machine.c   |    2 ++
>  5 files changed, 48 insertions(+), 1 deletions(-)
> 
> diff --git a/qemu-kvm-x86.c b/qemu-kvm-x86.c
> index fffcfd8..75e2ffd 100644
> --- a/qemu-kvm-x86.c
> +++ b/qemu-kvm-x86.c
> @@ -834,6 +834,9 @@ static int get_msr_entry(struct kvm_msr_entry *entry, CPUState *env)
>          case MSR_VM_HSAVE_PA:
>              env->vm_hsave     = entry->data;
>              break;
> +        case MSR_KVM_SYSTEM_TIME:
> +            env->system_time_msr = entry->data;
> +            break;
>          default:
>              printf("Warning unknown msr index 0x%x\n", entry->index);
>              return 1;
> @@ -1001,6 +1004,7 @@ void kvm_arch_load_regs(CPUState *env)
>          set_msr_entry(&msrs[n++], MSR_LSTAR  ,           env->lstar);
>      }
>  #endif
> +    set_msr_entry(&msrs[n++], MSR_KVM_SYSTEM_TIME,  env->system_time_msr);
>  
>      rc = kvm_set_msrs(env->kvm_cpu_state.vcpu_ctx, msrs, n);
>      if (rc == -1)
> @@ -1179,6 +1183,8 @@ void kvm_arch_save_regs(CPUState *env)
>          msrs[n++].index = MSR_LSTAR;
>      }
>  #endif
> +    msrs[n++].index = MSR_KVM_SYSTEM_TIME;
> +

fix MSR_COUNT for kvm_arch_save_regs()

Otherwise looks good.