Re: [Qemu-devel] [PATCH v4 2/3] target-i386: add migration support for Intel LMCE

[Haozhong Zhang]

On 06/16/16 12:41, Paolo Bonzini wrote:
> 
> 
> On 16/06/2016 12:29, Haozhong Zhang wrote:
> > On 06/16/16 11:51, Paolo Bonzini wrote:
> >>
> >>
> >> On 16/06/2016 08:06, Haozhong Zhang wrote:
> >>> Migration is only allowed between VCPUs with the same lmce option.
> >>>
> >>> Signed-off-by: Haozhong Zhang <address@hidden>
> >>> ---
> >>>  target-i386/machine.c | 25 +++++++++++++++++++++++++
> >>>  1 file changed, 25 insertions(+)
> >>>
> >>> diff --git a/target-i386/machine.c b/target-i386/machine.c
> >>> index cb9adf2..00375a3 100644
> >>> --- a/target-i386/machine.c
> >>> +++ b/target-i386/machine.c
> >>> @@ -347,6 +347,12 @@ static int cpu_post_load(void *opaque, int 
> >>> version_id)
> >>>          return -EINVAL;
> >>>      }
> >>>  
> >>> +    if (!cpu->enable_lmce && (env->mcg_cap & MCG_LMCE_P)) {
> >>> +        error_report("Config mismatch: VCPU has LMCE enabled, "
> >>> +                     "but \"lmce\" option is disabled");
> >>> +        return -EINVAL;
> >>> +    }
> >>> +
> >>
> >> I think this is unnecessary.  Apart from this, the patch is good and can
> >> be squashed in patch 1 for v5.
> >>
> > 
> > Without this check, the migration from LMCE enabled QEMU to LMCE
> > disabled QEMU will not fail. Is such configuration change considered
> > be error? If not, I will remove the error report and return, but add a
> > fix to remove MCG_LMCE_P from env->mcg_cap in this check.
> 
> It's considered a user error.  You can skip the "if" completely.
>

Eduardo said nice for this part in previous version [1], so we may wait
for his comments?

[1] http://lists.nongnu.org/archive/html/qemu-devel/2016-06/msg01992.html

Thanks,
Haozhong