> From: Tian, Kevin <kevin.tian@xxxxxxxxx> > Sent: Monday, March 30, 2020 9:19 PM > To: Liu, Yi L <yi.l.liu@xxxxxxxxx>; alex.williamson@xxxxxxxxxx; > Subject: RE: [PATCH v1 8/8] vfio/type1: Add vSVA support for IOMMU-backed > mdevs > > > From: Liu, Yi L <yi.l.liu@xxxxxxxxx> > > Sent: Sunday, March 22, 2020 8:32 PM > > > > 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). > > are->is got it. > > 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 > > "by an iommu domain which is auxiliary to the domain that the kernel driver > primarily uses for DMA API" yep. > > 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. > > "and then calling into the IOMMU layer to complete the vSVA operations on the aux > domain associated with that mdev" got it. > > > > 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); > > + 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); > > + 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); > > + else > > + return iommu_cache_invalidate(dc->domain, > > + dev, cache_inv_info); > > } > > possibly above could be simplified, e.g. > > static struct device *vfio_get_iommu_device(struct vfio_group *group, > struct device *dev) > { > if (group->mdev_group) > return vfio_mdev_get_iommu_device(dev); > else > return dev; > } > > Then use it to replace plain 'dev' in all three places. yes, better for reading. thanks. Regards, Yi Liu
