linux-kernel - Re: [PATCH v9 04/12] vfio iommu: Add support for mediated devices

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Date:   Fri, 21 Oct 2016 15:49:07 +0800
From:   Jike Song <jike.song@...el.com>
To:     Kirti Wankhede <kwankhede@...dia.com>
CC:     alex.williamson@...hat.com, pbonzini@...hat.com, kraxel@...hat.com,
        cjia@...dia.com, qemu-devel@...gnu.org, kvm@...r.kernel.org,
        kevin.tian@...el.com, bjsdjshi@...ux.vnet.ibm.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v9 04/12] vfio iommu: Add support for mediated devices

On 10/18/2016 05:22 AM, Kirti Wankhede wrote:
> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> index 2ba19424e4a1..5d67058a611d 100644
> --- a/drivers/vfio/vfio_iommu_type1.c
> +++ b/drivers/vfio/vfio_iommu_type1.c
[snip]
>  static int vfio_iommu_type1_attach_group(void *iommu_data,
>  					 struct iommu_group *iommu_group)
>  {
>  	struct vfio_iommu *iommu = iommu_data;
> -	struct vfio_group *group, *g;
> +	struct vfio_group *group;
>  	struct vfio_domain *domain, *d;
>  	struct bus_type *bus = NULL;
>  	int ret;
> @@ -746,10 +1136,14 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
>  	mutex_lock(&iommu->lock);
>  
>  	list_for_each_entry(d, &iommu->domain_list, next) {
> -		list_for_each_entry(g, &d->group_list, next) {
> -			if (g->iommu_group != iommu_group)
> -				continue;
> +		if (find_iommu_group(d, iommu_group)) {
> +			mutex_unlock(&iommu->lock);
> +			return -EINVAL;
> +		}
> +	}
>  
> +	if (iommu->local_domain) {
> +		if (find_iommu_group(iommu->local_domain, iommu_group)) {
>  			mutex_unlock(&iommu->lock);
>  			return -EINVAL;
>  		}
> @@ -769,6 +1163,30 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
>  	if (ret)
>  		goto out_free;
>  
> +	if (IS_ENABLED(CONFIG_VFIO_MDEV) && !iommu_present(bus) &&
> +	    (bus == &mdev_bus_type)) {

Hi Kirti,

By refering mdev_bus_type directly you are making vfio_iommu_type1.ko depends
on mdev.ko, but in Kconfig doesn't guarantee the dependency. For example,
if CONFIG_VFIO_IOMMU_TYPE1=y and CONFIG_VFIO_MDEV=m, the building will fail.


--
Thanks,
Jike