Re: [RFC 0/6] Enlightened VMCS support for KVM on Hyper-V

[Paolo Bonzini]

On 16/01/2018 14:58, Vitaly Kuznetsov wrote:
>> Haven't looked into the details, but we have to watch out for other
>> VCPUs trying to modify that vmcs12.
>>
>> Basically because other VCPUs could try to modify values in vmcs12 while
>> we are currently building vmcs02. Nasty races could result in us copying
>> stuff (probably unchecked) into vmcs02 and therefore running something
>> that was not intended.
>>
> I don't think we share VMCS among vCPUs, do we?

VMCS is just memory, so who knows what a malicious L1 guest will do.
But for vmread/vmwrite we can go through hypervisor memory, for
enlightened VMCS we cannot.

Paolo