On 16/11/2017 15:28, Quan Xu wrote:
> vcpu->srcu_idx = srcu_read_lock(&kvm->srcu);
>
> + kvm_load_guest_fpu(vcpu);
> +
> for (;;) {
> if (kvm_vcpu_running(vcpu)) {
> r = vcpu_enter_guest(vcpu);
>
> <<
>
>
>
> as Rik dropped kvm_load_guest_fpu(vcpu) in vcpu_enter_guest() ..
> in case still in kvm mode, how to make sure to pkru is always the
> right one before enter guest mode, not be preempted before
> preempt_disable() after migration? :(
As you know:
1) kvm_load_guest_fpu doesn't load the guest PKRU, it keeps the
userspace PKRU.
2) the guest PKRU is only ever set in a preemption-disabled area
Thus, context switch always sees the userspace PKRU. The guest PKRU is
only set the next time vmx_vcpu_run executes.
Paolo
