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

[Paolo Bonzini]

On 04/03/20 08:41, Liu, Jing2 wrote:
>> ÂÂÂÂÂ trace_kvm_entry(vcpu->vcpu_id);
>> ÂÂÂÂÂ guest_enter_irqoff();
>> Â -ÂÂÂ /* The preempt notifier should have taken care of the FPU
>> already. */
>> -ÂÂÂ WARN_ON_ONCE(test_thread_flag(TIF_NEED_FPU_LOAD));
>> +ÂÂÂ fpregs_assert_state_consistent();
>> +ÂÂÂ if (test_thread_flag(TIF_NEED_FPU_LOAD))
>> +ÂÂÂÂÂÂÂ switch_fpu_return();
>> Â ÂÂÂÂÂ if (unlikely(vcpu->arch.switch_db_regs)) {
>> ÂÂÂÂÂÂÂÂÂ set_debugreg(0, 7);
> 
> Can kvm be preempt out again after this (before really enter to guest)?

No, irqs are disabled here.

Paolo