On Mon, Apr 30, 2018 at 2:14 PM, Konrad Rzeszutek Wilk
<konrad.wilk@xxxxxxxxxx> wrote:
> On Fri, Apr 27, 2018 at 11:14:35AM -0700, Jim Mattson wrote:
>> Changing the VMCS12 layout breaks save/restore compatibility with
>> older kvm releases.
>>
>> Google has been saving/restoring nested VMX state based on the v4.0
>> layout. There are no other known users of the
>> KVM_{GET,SET}_NESTED_STATE ioctls, since those ioctls have not yet
>> been accepted upstream.
>
> What is the advantage of that layout vs the one that is now? I vaguelly
> recall something about it being quite bloated and the newer more sparse?
The only differences between the v4.0 layout and today's layout is
that four new fields have been intermingled in such a way that the old
offsets have not been preserved. I'm suggesting that these four fields
be moved so as to preserve the offsets of all of the pre-existing
fields.
