In the Linux kernel, the following vulnerability has been resolved:
KVM: nVMX: Hide shadow VMCS right after VMCLEAR
free_nested() frees the shadow VMCS while vmcs01 still points to it. But
because it is asynchronous with respect to loaded_vmcs_clear(), the vCPU
might migrate before the pointer is cleared and __loaded_vmcs_clear()
may then execute VMCLEAR.
The VMCS needs to stay attached until its explicit VMCLEAR completes, but
then it can be hidden and the page safely freed.
