Re: [PATCH v2 net] LoongArch: KVM: Add missing slots_lock for IO bus device register/unregister

[Bibo Mao]

On 2026/5/25 下午5:26, Zeng Chi wrote:
> From: Zeng Chi <zengchi@xxxxxxxxxx>
>
> kvm_io_bus_register_dev() and kvm_io_bus_unregister_dev() should be
> called under kvm->slots_lock. The unregister calls in ipi.c, pch_pic.c
> and eiointc.c were missing this protection. Add it to match the
> register side.
one small nit, the mail tile is [PATCH v2 net], I think it should be 
[PATCH v2] :)

> Signed-off-by: Zeng Chi <zengchi@xxxxxxxxxx>
> ---
>   arch/loongarch/kvm/intc/eiointc.c | 6 ++++++
>   arch/loongarch/kvm/intc/ipi.c     | 2 ++
>   arch/loongarch/kvm/intc/pch_pic.c | 2 ++
>   3 files changed, 10 insertions(+)
>
> diff --git a/arch/loongarch/kvm/intc/eiointc.c b/arch/loongarch/kvm/intc/eiointc.c
> index 2ab7fafa86d5..2b14485d14a7 100644
> --- a/arch/loongarch/kvm/intc/eiointc.c
> +++ b/arch/loongarch/kvm/intc/eiointc.c
> @@ -645,10 +645,14 @@ static int kvm_eiointc_create(struct kvm_device *dev, u32 type)
>   
>   	device = &s->device_vext;
>   	kvm_iodevice_init(device, &kvm_eiointc_virt_ops);
> +	mutex_lock(&kvm->slots_lock);
>   	ret = kvm_io_bus_register_dev(kvm, KVM_IOCSR_BUS,
>   			EIOINTC_VIRT_BASE, EIOINTC_VIRT_SIZE, device);
> +	mutex_unlock(&kvm->slots_lock);
>   	if (ret < 0) {
> +		mutex_lock(&kvm->slots_lock);
>   		kvm_io_bus_unregister_dev(kvm, KVM_IOCSR_BUS, &s->device);
> +		mutex_unlock(&kvm->slots_lock);
>   		kfree(s);
>   		return ret;
>   	}

I prefer something like this, however it is only my personal option.
--- a/arch/loongarch/kvm/intc/eiointc.c
+++ b/arch/loongarch/kvm/intc/eiointc.c
@@ -645,13 +645,16 @@ static int kvm_eiointc_create(struct kvm_device 
*dev, u32 type)

        device = &s->device_vext;
        kvm_iodevice_init(device, &kvm_eiointc_virt_ops);
+       mutex_lock(&kvm->slots_lock);
        ret = kvm_io_bus_register_dev(kvm, KVM_IOCSR_BUS,
                        EIOINTC_VIRT_BASE, EIOINTC_VIRT_SIZE, device);
        if (ret < 0) {
                kvm_io_bus_unregister_dev(kvm, KVM_IOCSR_BUS, &s->device);
+               mutex_unlock(&kvm->slots_lock);
                kfree(s);
                return ret;
        }
+       mutex_unlock(&kvm->slots_lock);
        kvm->arch.eiointc = s;

@chenhuacai what is your option?

The others look good to me.

Regards
Bibo Mao
> @@ -667,8 +671,10 @@ static void kvm_eiointc_destroy(struct kvm_device *dev)
>   
>   	kvm = dev->kvm;
>   	eiointc = kvm->arch.eiointc;
> +	mutex_lock(&kvm->slots_lock);
>   	kvm_io_bus_unregister_dev(kvm, KVM_IOCSR_BUS, &eiointc->device);
>   	kvm_io_bus_unregister_dev(kvm, KVM_IOCSR_BUS, &eiointc->device_vext);
> +	mutex_unlock(&kvm->slots_lock);
>   	kfree(eiointc);
>   	kfree(dev);
>   }
> diff --git a/arch/loongarch/kvm/intc/ipi.c b/arch/loongarch/kvm/intc/ipi.c
> index 1f6ebbd0af5c..4fa0897d7bdb 100644
> --- a/arch/loongarch/kvm/intc/ipi.c
> +++ b/arch/loongarch/kvm/intc/ipi.c
> @@ -447,7 +447,9 @@ static void kvm_ipi_destroy(struct kvm_device *dev)
>   
>   	kvm = dev->kvm;
>   	ipi = kvm->arch.ipi;
> +	mutex_lock(&kvm->slots_lock);
>   	kvm_io_bus_unregister_dev(kvm, KVM_IOCSR_BUS, &ipi->device);
> +	mutex_unlock(&kvm->slots_lock);
>   	kfree(ipi);
>   	kfree(dev);
>   }
> diff --git a/arch/loongarch/kvm/intc/pch_pic.c b/arch/loongarch/kvm/intc/pch_pic.c
> index aa0ed59ae8cf..175a630aceb4 100644
> --- a/arch/loongarch/kvm/intc/pch_pic.c
> +++ b/arch/loongarch/kvm/intc/pch_pic.c
> @@ -481,7 +481,9 @@ static void kvm_pch_pic_destroy(struct kvm_device *dev)
>   	kvm = dev->kvm;
>   	s = kvm->arch.pch_pic;
>   	/* unregister pch pic device and free it's memory */
> +	mutex_lock(&kvm->slots_lock);
>   	kvm_io_bus_unregister_dev(kvm, KVM_MMIO_BUS, &s->device);
> +	mutex_unlock(&kvm->slots_lock);
>   	kfree(s);
>   	kfree(dev);
>   }