Hi Marc,
On 4/2/19 10:48 AM, Marc Zyngier wrote:
> On Tue, 02 Apr 2019 09:22:29 +0100,
> Auger Eric <eric.auger@xxxxxxxxxx> wrote:
>>
>> Hi Marc,
>>
>> On 4/2/19 9:24 AM, Marc Zyngier wrote:
>>> When disabling LPIs (for example on reset) at the redistributor
>>> level, it is expected that LPIs that was pending in the CPU
>>> interface are eventually retired.
>>>
>>> Currently, this is not what is happening, and these LPIs will
>>> stay in the ap_list, eventually being acknowledged by the vcpu
>>> (which didn't quite expect this behaviour).
>>>
>>> The fix is thus to retire these LPIs from the list of pending
>>> interrupts as we disable LPIs.
>>>
>>> Reported-by: Heyi Guo <guoheyi@xxxxxxxxxx>
>>> Fixes: 0e4e82f154e3 ("KVM: arm64: vgic-its: Enable ITS emulation as a virtual MSI controller")
>>> Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
>>> ---
>>> Heyi,
>>>
>>> Can you please give this alternative patch a go on your setup?
>>> This should be a much better fit than my original hack.
>>>
>>> Thanks,
>>>
>>> M.
>>>
>>> virt/kvm/arm/vgic/vgic-mmio-v3.c | 3 +++
>>> virt/kvm/arm/vgic/vgic.c | 24 ++++++++++++++++++++++++
>>> virt/kvm/arm/vgic/vgic.h | 1 +
>>> 3 files changed, 28 insertions(+)
>>>
>>> diff --git a/virt/kvm/arm/vgic/vgic-mmio-v3.c b/virt/kvm/arm/vgic/vgic-mmio-v3.c
>>> index 4a12322bf7df..9f4843fe9cda 100644
>>> --- a/virt/kvm/arm/vgic/vgic-mmio-v3.c
>>> +++ b/virt/kvm/arm/vgic/vgic-mmio-v3.c
>>> @@ -200,6 +200,9 @@ static void vgic_mmio_write_v3r_ctlr(struct kvm_vcpu *vcpu,
>>>
>>> vgic_cpu->lpis_enabled = val & GICR_CTLR_ENABLE_LPIS;
>>>
>>> + if (was_enabled && !vgic_cpu->lpis_enabled)
>>> + vgic_flush_pending_lpis(vcpu);
>>> +
>>> if (!was_enabled && vgic_cpu->lpis_enabled)
>>> vgic_enable_lpis(vcpu);
>>> }
>>> diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
>>> index 3af69f2a3866..3f429cf2f694 100644
>>> --- a/virt/kvm/arm/vgic/vgic.c
>>> +++ b/virt/kvm/arm/vgic/vgic.c
>>> @@ -151,6 +151,30 @@ void vgic_put_irq(struct kvm *kvm, struct vgic_irq *irq)
>>> kfree(irq);
>>> }
>>>
>>> +void vgic_flush_pending_lpis(struct kvm_vcpu *vcpu)
>>> +{
>>> + struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
>>> + struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
>>> + struct vgic_irq *irq, *tmp;
>>> + unsigned long flags;
>>> +
>>> + raw_spin_lock_irqsave(&dist->lpi_list_lock, flags);
>> Do you need to hold the lpi_list_lock here as it is taken in vgic_put_irq.
>
> You're right, this is absolutely silly, as it violates the rules at
> the top of this very file. Don't write that kind of patches while
> being severely jet-lagged. It should be better with this on top.
>
> diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
> index 3f429cf2f694..191deccf60bf 100644
> --- a/virt/kvm/arm/vgic/vgic.c
> +++ b/virt/kvm/arm/vgic/vgic.c
> @@ -153,13 +153,11 @@ void vgic_put_irq(struct kvm *kvm, struct vgic_irq *irq)
>
> void vgic_flush_pending_lpis(struct kvm_vcpu *vcpu)
> {
> - struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
> struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
> struct vgic_irq *irq, *tmp;
> unsigned long flags;
>
> - raw_spin_lock_irqsave(&dist->lpi_list_lock, flags);
> - raw_spin_lock(&vgic_cpu->ap_list_lock);
> + raw_spin_lock_irqsave(&vgic_cpu->ap_list_lock, flags);
>
> list_for_each_entry_safe(irq, tmp, &vgic_cpu->ap_list_head, ap_list) {
> if (irq->intid >= VGIC_MIN_LPI) {
> @@ -171,8 +169,7 @@ void vgic_flush_pending_lpis(struct kvm_vcpu *vcpu)
> }
> }
>
> - raw_spin_unlock(&vgic_cpu->ap_list_lock);
> - raw_spin_unlock_irqrestore(&dist->lpi_list_lock, flags);
> + raw_spin_unlock_irqrestore(&vgic_cpu->ap_list_lock, flags);
> }
>
> void vgic_irq_set_phys_pending(struct vgic_irq *irq, bool pending)
>
>
>>> + raw_spin_lock(&vgic_cpu->ap_list_lock);
>>> +
>>> + list_for_each_entry_safe(irq, tmp, &vgic_cpu->ap_list_head, ap_list) {
>>> + if (irq->intid >= VGIC_MIN_LPI) {
>>> + raw_spin_lock(&irq->irq_lock);
>>> + list_del(&irq->ap_list);
>>> + irq->vcpu = NULL;
>>> + raw_spin_unlock(&irq->irq_lock);
>>> + vgic_put_irq(vcpu->kvm, irq);
>>> + }
>>> + }
>>> +
>>> + raw_spin_unlock(&vgic_cpu->ap_list_lock);
>>> + raw_spin_unlock_irqrestore(&dist->lpi_list_lock, flags);
>> A concern I have is how does this live with
>> vgic_v3_save_pending_tables/its_sync_lpi_pending_table ctrl flow. I need
>> to trace things.
>
> It shouldn't change a thing. The only thing this patch tries to do is
> to make sure that LPIs are not kept on the ap_list when they have been
> turned off at the redistributor level. The pending bits are still
> stored, and save/sync should work as expected (famous last words...).
Yes my concerns have gone away now :-)
Thanks
Eric
>
> Thanks,
>
> M.
>
