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

Liu, Jing2
2020-03-04T07:42:08Z

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