Re: [Qemu-devel] [QEMU PATCH v3 7/9] KVM: i386: Add support for save and restore nested state

[Paolo Bonzini]

On 18/06/19 17:48, Dr. David Alan Gilbert wrote:
>> Currently, KVM folks (including myself), haven’t decided yet to expose 
>> vmcs12 struct layout to userspace but instead to still leave it opaque.
>> The formal size of this size is VMCS12_SIZE (defined in kernel as 0x1000). I 
>> was wondering if we wish to expose VMCS12_SIZE constant to userspace or not.
>> So currently I defined these __u8 arrays as 0x1000. But in case Paolo agrees 
>> to expose VMCS12_SIZE, we can use that instead.
> Well if it's not defined it's bound to change at some state!
> Also, do we need to clear it before we get it from the kernel - e.g.
> is the kernel guaranteed to give us 0x1000 ?

It is defined, it is the size of data.vmx[0].vmx12.  We can define it.

Paolo