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

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

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>Hi Peng,
>
>On 15/11/18 15:14, Peng Hao wrote:
>> When virtual machine starts, hang up. The kernel version of guest
>> is 4.16. Host support vgic_v3.
>
>I don't understand the issue here. the vgic_irq->group field does not
>exist in 4.16 (neither in the first nor the last version). Nor does the
>line you are modifying.
Guest's kernel version is 4.16 and Host's kernel version is mainline.
vgic_irq is a structure of Host's kvm.
>
>Both exist in mainline, but what you are mentioning shouldn't be an
>issue in mainline since vgic_irq->group gets initialized in
>kvm_vgic_vcpu_init for SGIs and PPIs (i.e. intid < 32) which includes
>your interrupt.
Initialization sequence of several components is like this;
1.       kvm_vgic_vcpu_init ---- here, dist is not initialized at this time.
                                             and the value of irq->group depends on
                                              dist->vgic_model. but now dist->vgic_model = 0
                                               and irq->group=0.
 2.      vgic_create         -----  assign to dist->vgic_model.
 3.     kvm_vgic_dist_init 

thanks.
>
>Cheers,
>
>> 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.
>> 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)
>>           val |= ICH_LR_GROUP;
>>
>>       val |= (u64)irq->priority << ICH_LR_PRIORITY_SHIFT;
>>
>
>--
>Julien Thierry

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