On 17/06/19 13:34, Liran Alon wrote: > Putting this all together, in case kernel doesn’t support extracting > nested-state, there is no decent way to know if guest is running > nested-virtualization. Which means that in theory we always need to > fail migration in case kernel doesn’t support KVM_CAP_NESTED_STATE or > KVM_CAP_EXCEPTION_PAYLOAD and vCPU is exposed with VMX/SVM > capability.
For VMX this would be okay because we had a blocker before this series, and this wouldn't be any worse. For SVM we can ignore the case and fix it when we have KVM_CAP_NESTED_STATE, as again that wouldn't be any worse. Paolo > I can condition this behaviour with a flag that can be manipulated > using QMP to allow user to indicate it wishes to migrate guest anyway > in this case. This however bring me back to the entire discussion I > had with Dr. David Alan Gilbert on migration backwards compatibility > in general and the fact that I believe we should have a generic QMP > command which allows to provide list of VMState subsections that can > be ignored in migration… See: > https://www.mail-archive.com/qemu-devel@nongnu.org/msg622274.html > > Paolo, What are your thoughts on how I would proceed with this?
