Re: [PATCH 0/5] Convert virtio-iommu to domain_alloc_paging()

[Jacob Pan <jacob.pan@linux.microsoft.com>]

Hi Jason,

On Wed, 12 Feb 2025 08:50:07 -0400
Jason Gunthorpe <jgg@nvidia.com> wrote:

> On Tue, Feb 11, 2025 at 04:41:51PM -0800, Jacob Pan wrote:
> 
> > I see the same on arm64 with v9.0, assigned an ixgbe nic via VFIO.  
> 
> Huh, I figured it worked on ARM..
> 
> There is no requirement that an iommu driver implement identity, this
> is all an optimization. If it doesn't work in alot of cases can we
> just remove it? It would simplfy a lot..
> 
Currently, identity domain type can be set via sysfs. To prevent that,
maybe we need this?

+static int viommu_def_domain_type(struct device *dev)
+{
+  	return IOMMU_DOMAIN_DMA;
+}
+
 static struct iommu_ops viommu_ops = {
        .identity_domain        = &viommu_identity_domain.domain,
        .capable                = viommu_capable,
@@ -1096,6 +1106,7 @@ static struct iommu_ops viommu_ops = {
        .device_group           = viommu_device_group,
        .get_resv_regions       = viommu_get_resv_regions,
        .of_xlate               = viommu_of_xlate,
+       .def_domain_type = viommu_def_domain_type,
        .owner                  = THIS_MODULE,