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

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Date:   Thu, 15 Nov 2018 15:06:19 +0000
From:   Marc Zyngier <marc.zyngier@....com>
To:     Peng Hao <peng.hao2@....com.cn>
Cc:     <christoffer.dall@....com>, <linux-arm-kernel@...ts.infradead.org>,
        <kvmarm@...ts.cs.columbia.edu>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH]  kvm: arm/arm64 : fix vm's hanging at startup time

On Thu, 15 Nov 2018 15:14:08 +0000,
Peng Hao <peng.hao2@....com.cn> wrote:
> 
> When virtual machine starts, hang up. The kernel version of guest
> is 4.16. Host support vgic_v3.
> 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@....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;

This patch makes exactly zero sense. The group is a property of the
interrupt, and has nothing to do with the model used for the emulation

Which version of the kernel is this against? What userspace are you
using? How can I reproduce this issue?

Thanks,

	M.

-- 
Jazz is not dead, it just smell funny.