Hi Alex, > From: Alex Williamson <alex.william...@redhat.com> > Sent: Friday, August 21, 2020 5:49 AM > > On Mon, 27 Jul 2020 23:27:41 -0700 > Liu Yi L <yi.l....@intel.com> wrote: > > > Recent years, mediated device pass-through framework (e.g. vfio-mdev) > > is 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 > > Or a physical IOMMU backing device.
got it. :-) > > concept, which means mdevs are protected by an iommu domain which is > > auxiliary to the domain that the kernel driver primarily uses for DMA > > API. Details can be found in the KVM presentation as below: > > > > https://events19.linuxfoundation.org/wp-content/uploads/2017/12/\ > > Hardware-Assisted-Mediated-Pass-Through-with-VFIO-Kevin-Tian-Intel.pdf > > I think letting the line exceed 80 columns is preferable so that it's > clickable. Thanks, yeah, it's clickable now. will do it. :-) Thanks, Yi Liu > Alex > > > This patch extends NESTING_IOMMU ops to IOMMU-backed mdev devices. The > > main requirement is to use the auxiliary domain associated with mdev. > > > > Cc: Kevin Tian <kevin.t...@intel.com> > > CC: Jacob Pan <jacob.jun....@linux.intel.com> > > CC: Jun Tian <jun.j.t...@intel.com> > > Cc: Alex Williamson <alex.william...@redhat.com> > > Cc: Eric Auger <eric.au...@redhat.com> > > Cc: Jean-Philippe Brucker <jean-phili...@linaro.org> > > Cc: Joerg Roedel <j...@8bytes.org> > > Cc: Lu Baolu <baolu...@linux.intel.com> > > Reviewed-by: Eric Auger <eric.au...@redhat.com> > > Signed-off-by: Liu Yi L <yi.l....@intel.com> > > --- > > v5 -> v6: > > *) add review-by from Eric Auger. > > > > v1 -> v2: > > *) check the iommu_device to ensure the handling mdev is IOMMU-backed > > --- > > drivers/vfio/vfio_iommu_type1.c | 40 > > ++++++++++++++++++++++++++++++++++++---- > > 1 file changed, 36 insertions(+), 4 deletions(-) > > > > diff --git a/drivers/vfio/vfio_iommu_type1.c > > b/drivers/vfio/vfio_iommu_type1.c index bf95a0f..9d8f252 100644 > > --- a/drivers/vfio/vfio_iommu_type1.c > > +++ b/drivers/vfio/vfio_iommu_type1.c > > @@ -2379,20 +2379,41 @@ static int vfio_iommu_resv_refresh(struct > vfio_iommu *iommu, > > return ret; > > } > > > > +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; > > +} > > + > > static int vfio_dev_bind_gpasid_fn(struct device *dev, void *data) { > > struct domain_capsule *dc = (struct domain_capsule *)data; > > unsigned long arg = *(unsigned long *)dc->data; > > + struct device *iommu_device; > > + > > + iommu_device = vfio_get_iommu_device(dc->group, dev); > > + if (!iommu_device) > > + return -EINVAL; > > > > - return iommu_uapi_sva_bind_gpasid(dc->domain, dev, (void __user *)arg); > > + return iommu_uapi_sva_bind_gpasid(dc->domain, iommu_device, > > + (void __user *)arg); > > } > > > > static int vfio_dev_unbind_gpasid_fn(struct device *dev, void *data) > > { > > struct domain_capsule *dc = (struct domain_capsule *)data; > > unsigned long arg = *(unsigned long *)dc->data; > > + struct device *iommu_device; > > > > - iommu_uapi_sva_unbind_gpasid(dc->domain, dev, (void __user *)arg); > > + iommu_device = vfio_get_iommu_device(dc->group, dev); > > + if (!iommu_device) > > + return -EINVAL; > > + > > + iommu_uapi_sva_unbind_gpasid(dc->domain, iommu_device, > > + (void __user *)arg); > > return 0; > > } > > > > @@ -2401,8 +2422,13 @@ static int __vfio_dev_unbind_gpasid_fn(struct device > *dev, void *data) > > struct domain_capsule *dc = (struct domain_capsule *)data; > > struct iommu_gpasid_bind_data *unbind_data = > > (struct iommu_gpasid_bind_data *)dc->data; > > + struct device *iommu_device; > > + > > + iommu_device = vfio_get_iommu_device(dc->group, dev); > > + if (!iommu_device) > > + return -EINVAL; > > > > - iommu_sva_unbind_gpasid(dc->domain, dev, unbind_data); > > + iommu_sva_unbind_gpasid(dc->domain, iommu_device, unbind_data); > > return 0; > > } > > > > @@ -3060,8 +3086,14 @@ static int vfio_dev_cache_invalidate_fn(struct > > device *dev, void *data) { > > struct domain_capsule *dc = (struct domain_capsule *)data; > > unsigned long arg = *(unsigned long *)dc->data; > > + struct device *iommu_device; > > + > > + iommu_device = vfio_get_iommu_device(dc->group, dev); > > + if (!iommu_device) > > + return -EINVAL; > > > > - iommu_uapi_cache_invalidate(dc->domain, dev, (void __user *)arg); > > + iommu_uapi_cache_invalidate(dc->domain, iommu_device, > > + (void __user *)arg); > > return 0; > > } > >
