On 2014-03-07 18:28, Jan Kiszka wrote:
> On 2014-03-07 17:46, Paolo Bonzini wrote:
>> Il 07/03/2014 17:29, Jan Kiszka ha scritto:
>>> On 2014-03-07 16:44, Paolo Bonzini wrote:
>>>> With this patch do we still need
>>>>
>>>> if (is_guest_mode(vcpu) && nested_exit_on_intr(vcpu))
>>>> /*
>>>> * We get here if vmx_interrupt_allowed() said we can't
>>>> * inject to L1 now because L2 must run. The caller will have
>>>> * to make L2 exit right after entry, so we can inject to L1
>>>> * more promptly.
>>>> */
>>>> return -EBUSY;
>>>>
>>>> in enable_irq_window? If not, enable_nmi_window and enable_irq_window
>>>> can both return void.
>>>
>>> I don't see right now why this should have changed. We still cannot
>>> interrupt vmlaunch/vmresume.
>>
>> But then shouldn't the ame be true for enable_nmi_window? It doesn't
>> check is_guest_mode(vcpu) && nested_exit_on_nmi(vcpu).
>
> Yes, that seems wrong now. But I need to think this through again, why
> we may have excluded NMIs from this test so far.
>
>>
>> Since check_nested_events has already returned -EBUSY, perhaps the
>> following:
>>
>> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
>> index fda1028..df320e9 100644
>> --- a/arch/x86/kvm/vmx.c
>> +++ b/arch/x86/kvm/vmx.c
>> @@ -4522,15 +4522,6 @@ static int enable_irq_window(struct kvm_vcpu *vcpu)
>> {
>> u32 cpu_based_vm_exec_control;
>>
>> - if (is_guest_mode(vcpu) && nested_exit_on_intr(vcpu))
>> - /*
>> - * We get here if vmx_interrupt_allowed() said we can't
>> - * inject to L1 now because L2 must run. The caller will have
>> - * to make L2 exit right after entry, so we can inject to L1
>> - * more promptly.
>> - */
>> - return -EBUSY;
>> -
>> cpu_based_vm_exec_control = vmcs_read32(CPU_BASED_VM_EXEC_CONTROL);
>> cpu_based_vm_exec_control |= CPU_BASED_VIRTUAL_INTR_PENDING;
>> vmcs_write32(CPU_BASED_VM_EXEC_CONTROL, cpu_based_vm_exec_control);
>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>> index a03d611..83c2df5 100644
>> --- a/arch/x86/kvm/x86.c
>> +++ b/arch/x86/kvm/x86.c
>> @@ -5970,13 +5970,13 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
>>
>> inject_pending_event(vcpu);
>>
>> - if (is_guest_mode(vcpu) && kvm_x86_ops->check_nested_events)
>> - req_immediate_exit |=
>> - kvm_x86_ops->check_nested_events(vcpu,
>> - req_int_win) != 0;
>> + if (is_guest_mode(vcpu) &&
>> + kvm_x86_ops->check_nested_events &&
>> + kvm_x86_ops->check_nested_events(vcpu, req_int_win) != 0)
>> + req_immediate_exit = true;
>>
>> /* enable NMI/IRQ window open exits if needed */
>> - if (vcpu->arch.nmi_pending)
>> + else if (vcpu->arch.nmi_pending)
>> req_immediate_exit |=
>> kvm_x86_ops->enable_nmi_window(vcpu) != 0;
>> else if (kvm_cpu_has_injectable_intr(vcpu) || req_int_win)
>>
>
> Hmm, looks reasonable.
Also on second thought. I can give this hunk some test cycles here, just
in case.
Reading through my code again, I'm now wondering why I added
check_nested_events to both inject_pending_event and vcpu_enter_guest.
The former seems redundant, only vcpu_enter_guest calls
inject_pending_event. I guess I forgot a cleanup here.
I can fold in your changes when I resend for the other cleanup.
Jan
--
Siemens AG, Corporate Technology, CT RTC ITP SES-DE
Corporate Competence Center Embedded Linux
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