Re: [PATCH] LoongArch: KVM: Fix memory leak in kvm_loongarch_env_init() error path

[Bibo Mao]

On 2026/8/17 下午7:58, Chaithanya Lagisetty wrote:
> kvm_loongarch_env_init() allocates the per-CPU kvm_context (vmcs) and
> kvm_loongarch_ops, and registers the perf callbacks, before registering
> the IPI/EIOINTC/PCH-PIC/DMSINTC KVM devices. If any of those device
> registrations fails, the function returned the error directly without
> freeing vmcs and kvm_loongarch_ops or unregistering the perf callbacks.
> kvm_loongarch_init() propagates the error without calling
> kvm_loongarch_env_exit(), so these resources are leaked.
>
> Unwind the already-acquired resources on the error path, mirroring
> kvm_loongarch_env_exit().
>
> Fixes: c532de5a67a7 ("LoongArch: KVM: Add IPI device support")
> Signed-off-by: Chaithanya Lagisetty <nagachaithanya9911@xxxxxxxxx>
> ---
>   arch/loongarch/kvm/main.c | 19 +++++++++++++++----
>   1 file changed, 15 insertions(+), 4 deletions(-)
>
> diff --git a/arch/loongarch/kvm/main.c b/arch/loongarch/kvm/main.c
> index 3e1005526f4b..685d334cf957 100644
> --- a/arch/loongarch/kvm/main.c
> +++ b/arch/loongarch/kvm/main.c
> @@ -385,22 +385,33 @@ static int kvm_loongarch_env_init(void)
>   	/* Register LoongArch IPI interrupt controller interface. */
>   	ret = kvm_loongarch_register_ipi_device();
>   	if (ret)
> -		return ret;
> +		goto err;
>   
>   	/* Register LoongArch EIOINTC interrupt controller interface. */
>   	ret = kvm_loongarch_register_eiointc_device();
>   	if (ret)
> -		return ret;
> +		goto err;
>   
>   	/* Register LoongArch PCH-PIC interrupt controller interface. */
>   	ret = kvm_loongarch_register_pch_pic_device();
>   	if (ret)
> -		return ret;
> +		goto err;
It will be better if there is wrapped unregister function, to remove 
previous registered callback. The same with eiointc/dmsintc driver, 
something like this:
+
+void kvm_loongarch_unregister_pch_pic_device(void)
+{
+       return kvm_unregister_device_ops(KVM_DEV_TYPE_LOONGARCH_PCHPIC);
+}

Regards
Bibo Mao
>   
>   	/* Register LoongArch DMSINTC interrupt contrroller interface */
> -	if (cpu_has_msgint)
> +	if (cpu_has_msgint) {
>   		ret = kvm_loongarch_register_dmsintc_device();
> +		if (ret)
> +			goto err;
> +	}
>   
> +	return 0;
> +
> +err:
> +	kvm_unregister_perf_callbacks();
> +	kfree(kvm_loongarch_ops);
> +	kvm_loongarch_ops = NULL;
> +	free_percpu(vmcs);
> +	vmcs = NULL;
>   	return ret;
>   }
>