On 2014-03-07 19:19, Jan Kiszka wrote:
> 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.
Nah, it's not redundant, we need to check for potential L2->L2 switches
*before* trying deliver events to L2. But think I can (and probably
should) get rid of the second test in vcpu_enter_guest.
Jan
>
> 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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