Re: [PATCH] LoongArch: KVM: Return the actual error code in kvm_ipi_create()

[Bibo Mao]

On 2026/9/22 下午6:39, Chaithanya Lagisetty wrote:
> kvm_ipi_create() registers the IPI device on the IOCSR bus and jumps to
> the error label when that fails. The error path then discards the error
> code that kvm_io_bus_register_dev() reported and returns -EFAULT
> instead:
>
> 	ret = kvm_io_bus_register_dev(kvm, KVM_IOCSR_BUS, IOCSR_IPI_BASE,
> 				      IOCSR_IPI_SIZE, device);
> 	mutex_unlock(&kvm->slots_lock);
> 	if (ret < 0) {
> 		kvm_pr_unimpl("%s: Initialize IOCSR dev failed, ret = %d\n",
> 			      __func__, ret);
> 		goto err;
> 	}
> 	...
> err:
> 	kfree(s);
> 	return -EFAULT;
>
> kvm_io_bus_register_dev() fails with -ENOMEM or -ENOSPC, so userspace
> creating a KVM_DEV_TYPE_LOONGARCH_IPI device is told that it passed a
> bad address when the real problem is that the host is out of memory or
> out of IOCSR bus slots. -EFAULT is reserved for faulting user addresses,
> and the remaining -EFAULT returns in this file are get_user() failures,
> where it is correct.
>
> Return ret instead. It is guaranteed to hold a valid negative errno
> because the ret < 0 branch above is the only path that reaches the error
> label. This also matches kvm_eiointc_create(), which already propagates
> the kvm_io_bus_register_dev() error code unchanged.
>
> Only compile-tested; the fix is a straight propagation of an error code
> that the adjacent kvm_pr_unimpl() already logs.
>
> Fixes: c532de5a67a7 ("LoongArch: KVM: Add IPI device support")
> Assisted-by: Cursor:claude-opus-5
> Signed-off-by: Chaithanya Lagisetty <nagachaithanya9911@xxxxxxxxx>
> ---
>   arch/loongarch/kvm/intc/ipi.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/loongarch/kvm/intc/ipi.c b/arch/loongarch/kvm/intc/ipi.c
> index 7b333a4a0430..672ec053a997 100644
> --- a/arch/loongarch/kvm/intc/ipi.c
> +++ b/arch/loongarch/kvm/intc/ipi.c
> @@ -431,7 +431,7 @@ static int kvm_ipi_create(struct kvm_device *dev, u32 type)
>   
>   err:
>   	kfree(s);
> -	return -EFAULT;
> +	return ret;
>   }
>   
>   static void kvm_ipi_destroy(struct kvm_device *dev)
Reviewed-by: Bibo Mao <maobibo@xxxxxxxxxxx>