Re: [Qemu-devel] [PATCH 9/9] qemu/kvm: kvm hyper-v based guest crash event handling

[Paolo Bonzini <pbonzini@redhat.com>]

On 02/07/2015 15:19, Andrey Smetanin wrote:
>>> > > +    if (has_msr_hv_crash) {
>>> > > +            env->msr_hv_crash_ctl = HV_X64_MSR_CRASH_CTL_NOTIFY;
>> > 
>> > The value is always host-defined, so I think it doesn't need a field in
>> > CPUX86State.  On the other hand, this:
> Kernel just works with that value, kernel doesn't setup it. 
> The user space is allowed to setup this msr if qemu option "hv-crash" is
> on. So the code "env->msr_hv_crash_ctl = HV_X64_MSR_CRASH_CTL_NOTIFY;"
> setups msr in user space at cpu reset. When cpu setup it's registers
> these msr's values are uploaded into kernel.
> 
> Anyway we need a code that initially set up crash ctl msr with value
> HV_X64_MSR_CRASH_CTL_NOTIFY. And I think that code should be user space.
> Any objections ?

Yes, that's correct.

What I'm saying, is that the value can be hard-coded and doesn't need a
field in CPUX86State.  If you want to leave the field that's also okay,
but even then it should not be part of the migration state.

Paolo