> From: Tian, Kevin
> Sent: Thursday, October 14, 2021 11:25 AM
>
> > From: Jean-Philippe Brucker <jean-phili...@linaro.org>
> > Sent: Wednesday, October 13, 2021 8:11 PM
> >
> > The VIRTIO_IOMMU_F_BYPASS_CONFIG feature adds a new flag to the
> > ATTACH
> > request, that creates a bypass domain. Use it to enable identity
> > domains.
> >
> > When VIRTIO_IOMMU_F_BYPASS_CONFIG is not supported by the device,
> > we
> > currently fail attaching to an identity domain. Future patches will
> > instead create identity mappings in this case.
> >
> > Signed-off-by: Jean-Philippe Brucker <jean-phili...@linaro.org>
> > ---
> > drivers/iommu/virtio-iommu.c | 20 +++++++++++++++++++-
> > 1 file changed, 19 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/iommu/virtio-iommu.c b/drivers/iommu/virtio-iommu.c
> > index 80930ce04a16..ee8a7afd667b 100644
> > --- a/drivers/iommu/virtio-iommu.c
> > +++ b/drivers/iommu/virtio-iommu.c
> > @@ -71,6 +71,7 @@ struct viommu_domain {
> > struct rb_root_cached mappings;
> >
> > unsigned long nr_endpoints;
> > + bool bypass;
> > };
> >
> > struct viommu_endpoint {
> > @@ -587,7 +588,9 @@ static struct iommu_domain
> > *viommu_domain_alloc(unsigned type)
> > {
> > struct viommu_domain *vdomain;
> >
> > - if (type != IOMMU_DOMAIN_UNMANAGED && type !=
> > IOMMU_DOMAIN_DMA)
> > + if (type != IOMMU_DOMAIN_UNMANAGED &&
> > + type != IOMMU_DOMAIN_DMA &&
> > + type != IOMMU_DOMAIN_IDENTITY)
> > return NULL;
> >
> > vdomain = kzalloc(sizeof(*vdomain), GFP_KERNEL);
> > @@ -630,6 +633,17 @@ static int viommu_domain_finalise(struct
> > viommu_endpoint *vdev,
> > vdomain->map_flags = viommu->map_flags;
> > vdomain->viommu = viommu;
> >
> > + if (domain->type == IOMMU_DOMAIN_IDENTITY) {
> > + if (!virtio_has_feature(viommu->vdev,
> > + VIRTIO_IOMMU_F_BYPASS_CONFIG))
> > {
> > + ida_free(&viommu->domain_ids, vdomain->id);
> > + vdomain->viommu = 0;
> > + return -EOPNOTSUPP;
> > + }
> > +
> > + vdomain->bypass = true;
> > + }
> > +
>
> move to the start of the function, then no need for above cleanup.
>
forgot it as I see the reason now when looking at patch05
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