Re: Does Xen support nested VM migration

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 01/07/15 09:56, Han, Huaitong wrote:
> On Wed, 2015-07-01 at 08:50 +0100, Andrew Cooper wrote:
>> On 01/07/2015 03:49, Han, Huaitong wrote:
>>> Hi, all,
>>>  
>>> When I create a L1 guest with nestedhvm=1, and create a L2 guest in L1
>>> guest, then migrate L1 guest, but the operation fails, and I find the
>>> bugfix requires a lot of work.
>> Fails in what way?
> The xen hypervisor in L1 guest has execute "vmxon" and
> nvmx->vmxon_region_pa get the value, after L1 migration, vmxon impact is
> lost and nvmx->vmxon_region_pa==0 , when L2 guest has some operation
> like VMREAD or VMWRITE,  vmx_inst_check_privilege will return 1, and L1
> guest maybe hang or panic.

Ah yes - I remember this now.  I raised it as a concern about a year ago
when rewriting migration and finding no information along these lines in
the migration stream.

To support this, you will need to add a new per-vcpu record in the
hypervisor migration stream which sends the VMX architectural state from
the source to the destination.

~Andrew