Re: [PATCH 3/4] KVM: x86: Revert "KVM: X86: Fix fpu state crash in kvm guest"

["Liu, Jing2" <jing2.liu@xxxxxxxxxxxxxxx>]

On 1/17/2020 2:26 PM, Sean Christopherson wrote:
> @@ -8198,8 +8194,9 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
>   	trace_kvm_entry(vcpu->vcpu_id);
>   	guest_enter_irqoff();
>   
> -	/* The preempt notifier should have taken care of the FPU already.  */
> -	WARN_ON_ONCE(test_thread_flag(TIF_NEED_FPU_LOAD));
> +	fpregs_assert_state_consistent();
> +	if (test_thread_flag(TIF_NEED_FPU_LOAD))
> +		switch_fpu_return();
>   
>   	if (unlikely(vcpu->arch.switch_db_regs)) {
>   		set_debugreg(0, 7);

Can kvm be preempt out again after this (before really enter to guest)?

Thanks,

Jing