Re:Re: [PATCH] kvm: arm/arm64 : fix vm's hanging at startup time

[<peng.hao2@zte.com.cn>]

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>On 16/11/18 00:23, peng.hao2@zte.com.cn wrote:
>>> Hi,
>>>> When virtual machine starts, hang up.
>>>
>>> I take it you mean the *guest* hangs? Because it doesn't get a timer
>>> interrupt?
>>>
>>>> The kernel version of guest
>>>> is 4.16. Host support vgic_v3.
>>>
>>> Your host kernel is something recent, I guess?
>>>
>>>> It was mainly due to the incorrect vgic_irq's(intid=27) group value
>>>> during injection interruption. when kvm_vgic_vcpu_init is called,
>>>> dist is not initialized at this time. Unable to get vgic V3 or V2
>>>> correctly, so group is not set.
>>>
>>> Mmh, that shouldn't happen with (v)GICv3. Do you use QEMU (which
>>> version?) or some other userland tool?
>>>
>>
>> QEMU emulator version 3.0.50 .
>>
>>>> group is setted to 1 when vgic_mmio_write_group is invoked at some
>>>> time.
>>>> when irq->group=0 (intid=27), No ICH_LR_GROUP flag was set and
>>>> interrupt injection failed.
>>>>
>>>> Signed-off-by: Peng Hao <peng.hao2@zte.com.cn>
>>>> ---
>>>>   virt/kvm/arm/vgic/vgic-v3.c | 2 +-
>>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/virt/kvm/arm/vgic/vgic-v3.c b/virt/kvm/arm/vgic/vgic-v3.c
>>>> index 9c0dd23..d101000 100644
>>>> --- a/virt/kvm/arm/vgic/vgic-v3.c
>>>> +++ b/virt/kvm/arm/vgic/vgic-v3.c
>>>> @@ -198,7 +198,7 @@ void vgic_v3_populate_lr(struct kvm_vcpu *vcpu,
>>>> struct vgic_irq *irq, int lr) if (vgic_irq_is_mapped_level(irq) &&
>>>> (val & ICH_LR_PENDING_BIT)) irq->line_level = false;
>>>>
>>>> -    if (irq->group)
>>>> +    if (model == KVM_DEV_TYPE_ARM_VGIC_V3)
>>>
>>> This is not the right fix, not only because it basically reverts the
>>> GICv3 part of 87322099052 (KVM: arm/arm64: vgic: Signal IRQs using
>>> their configured group).
>>>
>>> Can you try to work out why kvm_vgic_vcpu_init() is apparently called
>>> before dist->vgic_model is set, also what value it has?
>>> If I understand the code correctly, that shouldn't happen for a GICv3.
>>>
>> Even if the value of  group is correctly assigned in kvm_vgic_vcpu_init, the group is then written 0 through vgic_mmio_write_group.
>>   If the interrupt comes at this time, the interrupt injection fails.
>>
>
>Does that mean that the guest is configuring its interrupts as Group0?
>That sounds wrong, Linux should configure all it's interrupts as
>non-secure group1.

no, I think that uefi dose this, not linux.
1. kvm_vgic_vcpu_init 
2. vgic_create 
3. kvm_vgic_dist_init 
4.vgic_mmio_write_group: uefi as guest, write group=0
5.vgic_mmio_write_group: linux as guest, write group=1

>
>--
>Julien Thierry

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