Re: [PATCH v3 0/1] Introduce VCPUOP_reset_vcpu_info

[Vitaly Kuznetsov <vkuznets@redhat.com>]

David Vrabel <dvrabel@cantab.net> writes:

> On 19/08/14 11:04, Vitaly Kuznetsov wrote:
>> The patch and guest code are based on the prototype by Konrad Rzeszutek Wilk.
>>
>> VCPUOP_reset_vcpu_info is required to support kexec performed by smp pvhvm
>> guest. It was tested with the guest code listed below.
>
> Instead of having the guest teardown all these bits of  setup.  I
> think it would be preferable to have the toolstack build a new domain
> with the same memory contents from the original VM.  The toolstack
> would then start this new domain at the kexec entry point.
>
> The advantage of this is you don't need to add new hypercall sub-ops
> to teardown all bits and pieces, both for existing stuff and for
> anything new that might be added.

I agree this might be the more general approach to kexec. However, I
also think that having 'paired'  operations in hypervisor is a nice
thing to have: e.g. if we have EVTCHNOP_init_control that we need an op
to switch back, if there is VCPUOP_register_vcpu_info there should
be a sort of VCPUOP_reset_vcpu_info ...

The other question would be how can toolstack determine that hvm guest
is performing kexec/kdump? I can imaging some sort of a special
toolstack-handled call with new entry point as a parameter.. 

>
> David

-- 
  Vitaly