On Sun, 22 Mar 2020 05:32:05 -0700 "Liu, Yi L" <yi.l.liu@xxxxxxxxx> wrote: > From: Liu Yi L <yi.l.liu@xxxxxxxxx> > > Recent years, mediated device pass-through framework (e.g. vfio-mdev) > are used to achieve flexible device sharing across domains (e.g. VMs). > Also there are hardware assisted mediated pass-through solutions from > platform vendors. e.g. Intel VT-d scalable mode which supports Intel > Scalable I/O Virtualization technology. Such mdevs are called IOMMU- > backed mdevs as there are IOMMU enforced DMA isolation for such mdevs. > In kernel, IOMMU-backed mdevs are exposed to IOMMU layer by aux-domain > concept, which means mdevs are protected by an iommu domain which is > aux-domain of its physical device. Details can be found in the KVM > presentation from Kevin Tian. IOMMU-backed equals to IOMMU-capable. > > https://events19.linuxfoundation.org/wp-content/uploads/2017/12/\ > Hardware-Assisted-Mediated-Pass-Through-with-VFIO-Kevin-Tian-Intel.pdf > > This patch supports NESTING IOMMU for IOMMU-backed mdevs by figuring > out the physical device of an IOMMU-backed mdev and then invoking IOMMU > requests to IOMMU layer with the physical device and the mdev's aux > domain info. > > With this patch, vSVA (Virtual Shared Virtual Addressing) can be used > on IOMMU-backed mdevs. > > Cc: Kevin Tian <kevin.tian@xxxxxxxxx> > CC: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx> > CC: Jun Tian <jun.j.tian@xxxxxxxxx> > Cc: Alex Williamson <alex.williamson@xxxxxxxxxx> > Cc: Eric Auger <eric.auger@xxxxxxxxxx> > Cc: Jean-Philippe Brucker <jean-philippe@xxxxxxxxxx> > Signed-off-by: Liu Yi L <yi.l.liu@xxxxxxxxx> > --- > drivers/vfio/vfio_iommu_type1.c | 23 ++++++++++++++++++++--- > 1 file changed, 20 insertions(+), 3 deletions(-) > > diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c > index 937ec3f..d473665 100644 > --- a/drivers/vfio/vfio_iommu_type1.c > +++ b/drivers/vfio/vfio_iommu_type1.c > @@ -132,6 +132,7 @@ struct vfio_regions { > > struct domain_capsule { > struct iommu_domain *domain; > + struct vfio_group *group; > void *data; > }; > > @@ -148,6 +149,7 @@ static int vfio_iommu_for_each_dev(struct vfio_iommu *iommu, > list_for_each_entry(d, &iommu->domain_list, next) { > dc.domain = d->domain; > list_for_each_entry(g, &d->group_list, next) { > + dc.group = g; > ret = iommu_group_for_each_dev(g->iommu_group, > &dc, fn); > if (ret) > @@ -2347,7 +2349,12 @@ static int vfio_bind_gpasid_fn(struct device *dev, void *data) > struct iommu_gpasid_bind_data *gbind_data = > (struct iommu_gpasid_bind_data *) dc->data; > > - return iommu_sva_bind_gpasid(dc->domain, dev, gbind_data); > + if (dc->group->mdev_group) > + return iommu_sva_bind_gpasid(dc->domain, > + vfio_mdev_get_iommu_device(dev), gbind_data); But we can't assume an mdev device is iommu backed, so this can call with NULL dev, which appears will pretty quickly segfault intel_svm_bind_gpasid. > + else > + return iommu_sva_bind_gpasid(dc->domain, > + dev, gbind_data); > } > > static int vfio_unbind_gpasid_fn(struct device *dev, void *data) > @@ -2356,8 +2363,13 @@ static int vfio_unbind_gpasid_fn(struct device *dev, void *data) > struct iommu_gpasid_bind_data *gbind_data = > (struct iommu_gpasid_bind_data *) dc->data; > > - return iommu_sva_unbind_gpasid(dc->domain, dev, > + if (dc->group->mdev_group) > + return iommu_sva_unbind_gpasid(dc->domain, > + vfio_mdev_get_iommu_device(dev), > gbind_data->hpasid); Same > + else > + return iommu_sva_unbind_gpasid(dc->domain, dev, > + gbind_data->hpasid); > } > > /** > @@ -2429,7 +2441,12 @@ static int vfio_cache_inv_fn(struct device *dev, void *data) > struct iommu_cache_invalidate_info *cache_inv_info = > (struct iommu_cache_invalidate_info *) dc->data; > > - return iommu_cache_invalidate(dc->domain, dev, cache_inv_info); > + if (dc->group->mdev_group) > + return iommu_cache_invalidate(dc->domain, > + vfio_mdev_get_iommu_device(dev), cache_inv_info); And again > + else > + return iommu_cache_invalidate(dc->domain, > + dev, cache_inv_info); > } > > static long vfio_iommu_type1_ioctl(void *iommu_data,
