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Date:   Mon, 14 Mar 2022 18:38:08 -0300
From:   Jason Gunthorpe <jgg@nvidia.com>
To:     Matthew Rosato <mjrosato@linux.ibm.com>
Cc:     linux-s390@vger.kernel.org, alex.williamson@redhat.com,
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Subject: Re: [PATCH v4 15/32] vfio: introduce KVM-owned IOMMU type
Message-ID: <20220314213808.GI11336@nvidia.com>
References: <20220314194451.58266-1-mjrosato@linux.ibm.com>
 <20220314194451.58266-16-mjrosato@linux.ibm.com>
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On Mon, Mar 14, 2022 at 03:44:34PM -0400, Matthew Rosato wrote:

> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> index 9394aa9444c1..0bec97077d61 100644
> +++ b/drivers/vfio/vfio_iommu_type1.c
> @@ -77,6 +77,7 @@ struct vfio_iommu {
>  	bool			nesting;
>  	bool			dirty_page_tracking;
>  	bool			container_open;
> +	bool			kvm;
>  	struct list_head	emulated_iommu_groups;
>  };
>  
> @@ -2203,7 +2204,12 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
>  		goto out_free_group;
>  
>  	ret = -EIO;
> -	domain->domain = iommu_domain_alloc(bus);
> +
> +	if (iommu->kvm)
> +		domain->domain = iommu_domain_alloc_type(bus, IOMMU_DOMAIN_KVM);
> +	else
> +		domain->domain = iommu_domain_alloc(bus);
> +
>  	if (!domain->domain)
>  		goto out_free_domain;
>  
> @@ -2552,6 +2558,9 @@ static void *vfio_iommu_type1_open(unsigned long arg)
>  	case VFIO_TYPE1v2_IOMMU:
>  		iommu->v2 = true;
>  		break;
> +	case VFIO_KVM_IOMMU:
> +		iommu->kvm = true;
> +		break;

Same remark for this - but more - this is called KVM but it doesn't
accept a kvm FD or any thing else to link the domain to the KVM
in-use.

Jason