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SubjectRe: [RFC v2 06/10] KVM: arm/arm64: Update the physical timer interrupt level
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On 01/02/17 10:07, Christoffer Dall wrote:
> On Wed, Feb 01, 2017 at 03:40:10AM -0500, Jintack Lim wrote:
>> On Wed, Feb 1, 2017 at 3:04 AM, Christoffer Dall
>> <christoffer.dall@linaro.org> wrote:
>>> On Sun, Jan 29, 2017 at 03:21:06PM +0000, Marc Zyngier wrote:
>>>> On Fri, Jan 27 2017 at 01:04:56 AM, Jintack Lim <jintack@cs.columbia.edu> wrote:
>>>>> Now that we maintain the EL1 physical timer register states of VMs,
>>>>> update the physical timer interrupt level along with the virtual one.
>>>>>
>>>>> Note that the emulated EL1 physical timer is not mapped to any hardware
>>>>> timer, so we call a proper vgic function.
>>>>>
>>>>> Signed-off-by: Jintack Lim <jintack@cs.columbia.edu>
>>>>> ---
>>>>> virt/kvm/arm/arch_timer.c | 20 ++++++++++++++++++++
>>>>> 1 file changed, 20 insertions(+)
>>>>>
>>>>> diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c
>>>>> index 0f6e935..3b6bd50 100644
>>>>> --- a/virt/kvm/arm/arch_timer.c
>>>>> +++ b/virt/kvm/arm/arch_timer.c
>>>>> @@ -180,6 +180,21 @@ static void kvm_timer_update_mapped_irq(struct kvm_vcpu *vcpu, bool new_level,
>>>>> WARN_ON(ret);
>>>>> }
>>>>>
>>>>> +static void kvm_timer_update_irq(struct kvm_vcpu *vcpu, bool new_level,
>>>>> + struct arch_timer_context *timer)
>>>>> +{
>>>>> + int ret;
>>>>> +
>>>>> + BUG_ON(!vgic_initialized(vcpu->kvm));
>>>>
>>>> Although I've added my fair share of BUG_ON() in the code base, I've
>>>> since reconsidered my position. If we get in a situation where the vgic
>>>> is not initialized, maybe it would be better to just WARN_ON and return
>>>> early rather than killing the whole box. Thoughts?
>>>>
>>>
>>> Could we help this series along by saying that since this BUG_ON already
>>> exists in the kvm_timer_update_mapped_irq function, then it just
>>> preserves functionality and it's up to someone else (me) to remove the
>>> BUG_ON from both functions later in life?
>>>
>>
>> Sounds good to me :) Thanks!
>>
>
> So just as you thought you were getting off easy...
>
> The reason we now have kvm_timer_update_irq and
> kvm_timer_update_mapped_irq is that we have the following two vgic
> functions:
>
> kvm_vgic_inject_irq
> kvm_vgic_inject_mapped_irq
>
> But the only difference between the two is what they pass
> as the mapped_irq argument to vgic_update_irq_pending.
>
> What about if we just had this as a precursor patch:
>
> diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c
> index 6a084cd..91ecf48 100644
> --- a/virt/kvm/arm/arch_timer.c
> +++ b/virt/kvm/arm/arch_timer.c
> @@ -175,7 +175,8 @@ static void kvm_timer_update_irq(struct kvm_vcpu *vcpu, bool new_level)
> timer->irq.level = new_level;
> trace_kvm_timer_update_irq(vcpu->vcpu_id, timer->irq.irq,
> timer->irq.level);
> - ret = kvm_vgic_inject_mapped_irq(vcpu->kvm, vcpu->vcpu_id,
> +
> + ret = kvm_vgic_inject_irq(vcpu->kvm, vcpu->vcpu_id,
> timer->irq.irq,
> timer->irq.level);
> WARN_ON(ret);
> diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
> index dea12df..4c87fd0 100644
> --- a/virt/kvm/arm/vgic/vgic.c
> +++ b/virt/kvm/arm/vgic/vgic.c
> @@ -336,8 +336,7 @@ bool vgic_queue_irq_unlock(struct kvm *kvm, struct vgic_irq *irq)
> }
>
> static int vgic_update_irq_pending(struct kvm *kvm, int cpuid,
> - unsigned int intid, bool level,
> - bool mapped_irq)
> + unsigned int intid, bool level)
> {
> struct kvm_vcpu *vcpu;
> struct vgic_irq *irq;
> @@ -357,11 +356,6 @@ static int vgic_update_irq_pending(struct kvm *kvm, int cpuid,
> if (!irq)
> return -EINVAL;
>
> - if (irq->hw != mapped_irq) {
> - vgic_put_irq(kvm, irq);
> - return -EINVAL;
> - }
> -
> spin_lock(&irq->irq_lock);
>
> if (!vgic_validate_injection(irq, level)) {
> @@ -399,13 +393,7 @@ static int vgic_update_irq_pending(struct kvm *kvm, int cpuid,
> int kvm_vgic_inject_irq(struct kvm *kvm, int cpuid, unsigned int intid,
> bool level)
> {
> - return vgic_update_irq_pending(kvm, cpuid, intid, level, false);
> -}
> -
> -int kvm_vgic_inject_mapped_irq(struct kvm *kvm, int cpuid, unsigned int intid,
> - bool level)
> -{
> - return vgic_update_irq_pending(kvm, cpuid, intid, level, true);
> + return vgic_update_irq_pending(kvm, cpuid, intid, level);
> }
>
> int kvm_vgic_map_phys_irq(struct kvm_vcpu *vcpu, u32 virt_irq, u32 phys_irq)
>
>
> That would make this patch simpler. If so, I can send out the above
> patch with a proper description.

Indeed. And while you're at it, rename vgic_update_irq_pending to
kvm_vgic_inject_irq, as I don't think we need this simple stub?

Thanks,

M.
--
Jazz is not dead. It just smells funny...

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