Re: [Qemu-devel] [PATCH 2/2] KVM: s390: add floating irq controller

[Cornelia Huck <cornelia.huck@de.ibm.com>]

On Mon, 29 Jul 2013 15:59:53 +0200
Jens Freimann <jfrei@linux.vnet.ibm.com> wrote:

> This patch adds a floating irq controller as a kvm_device.
> It will be necesary for migration of floating interrupts as well
> as for hardening the reset code by allowing user space to explicitly
> remove all pending floating interrupts.
> 
> Signed-off-by: Jens Freimann <jfrei@linux.vnet.ibm.com>
> ---
>  arch/s390/include/uapi/asm/kvm.h |   5 +
>  arch/s390/kvm/interrupt.c        | 210 +++++++++++++++++++++++++++++++--------
>  arch/s390/kvm/kvm-s390.c         |   1 +
>  include/linux/kvm_host.h         |   1 +
>  include/uapi/linux/kvm.h         |   1 +
>  virt/kvm/kvm_main.c              |   3 +
>  6 files changed, 181 insertions(+), 40 deletions(-)
> 

> +static int flic_set_attr(struct kvm_device *dev, struct kvm_device_attr *attr)
> +{
> +	int r;
> +	struct kvm_s390_irq *s390irq;
> +	struct kvm_s390_interrupt_info *inti;
> +
> +	switch (attr->group) {
> +	case KVM_DEV_FLIC_ENQUEUE:
> +		inti = kzalloc(sizeof(*inti), GFP_KERNEL);
> +		if (!inti) {
> +			r = -ENOMEM;
> +			goto out;
> +		}
> +		s390irq = kzalloc(sizeof(*s390irq), GFP_KERNEL);
> +		if (!s390irq) {
> +			r = -ENOMEM;
> +			goto out_free_inti;
> +		}
> +		if (copy_from_user(s390irq, (u64 __user *)attr->addr,
> +				  sizeof(s390irq))) {
> +			r = -EFAULT;
> +			goto out_free_s390irq;
> +		}

Can't you just copy into inti->irq here? You'd get rid of allocating
two structures that way.

> +		switch(s390irq->type) {
> +		case KVM_S390_INT_VIRTIO:
> +		case KVM_S390_INT_SERVICE:
> +		case KVM_S390_INT_IO_MIN...KVM_S390_INT_IO_MAX:
> +		case KVM_S390_MCHK:
> +			inti->irq = *s390irq;
> +			__inject_vm(dev->kvm, inti);
> +		default:
> +			r = -EINVAL;
> +		}
> +		break;
> +	case KVM_DEV_FLIC_CLEAR_IRQS:
> +		clear_floating_interrupts(dev->kvm);
> +	default:
> +		r = -EINVAL;
> +		goto out;
> +	}
> +
> +out_free_s390irq:
> +	kfree(s390irq);
> +out_free_inti:
> +	kfree(inti);
> +out:
> +	return r;
> +}