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

From: Liu, Jing2
Date: Wed Mar 04 2020 - 02:42:06 EST



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