Contents of XMM registers should be preserved during VM-exit handling

[tandasat]

As it is reported in #3, HyperPlatform does not preserve contents of XMM registers when VM-exit occurs. This can corrupt guest's context if a VM-exit handler modifies XMM registers and a guest uses those modified values, and result in unexpected failure in a guest (most likely system crash).

In order to avoid this issue, the VMM should probably save contents of XMM registers on VM-exit, and restore them before VM-enter so that modification of those registers by the VMM does not leak to guest's state.

[tandasat]

As of now, no update is planed since any issue due to modified XMM registers has not seen yet. If you faced this issue, please flag it up so that this bug can be prioritized.

[tandasat]

already fixed with 7bcb1a7