CVE-2021-47112

In the Linux kernel, the following vulnerability has been resolved:

x86/kvm: Teardown PV features on boot CPU as well

Various PV features (Async PF, PV EOI, steal time) work through memory

shared with hypervisor and when we restore from hibernation we must

properly teardown all these features to make sure hypervisor doesn't

write to stale locations after we jump to the previously hibernated kernel

(which can try to place anything there). For secondary CPUs the job is

already done by kvm_cpu_down_prepare(), register syscore ops to do

the same for boot CPU.