[RESEND] Atomic switch of MSR_IA32_UMWAIT_CONTROL

[Sean Christopherson]

cc'ing KVM and LKML this time...

Why does KVM use the atomic load/store lists to load MSR_IA32_UMWAIT_CONTROL
on VM-Enter/VM-Exit?  Unless the host kernel is doing UWMAIT, which it
really shouldn't and AFAICT doesn't, isn't it better to use the shared MSR
mechanism to load the host value only when returning to userspace, and
reload the guest value on demand?