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charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On Wed, 29 Jul 2020 23:49:20 +0000 "Tian, Kevin" wrote: > > From: Alex Williamson > > Sent: Thursday, July 30, 2020 4:25 AM > > > > On Tue, 14 Jul 2020 13:57:02 +0800 > > Lu Baolu wrote: > > > > > The device driver needs an API to get its aux-domain. A typical usage > > > scenario is: > > > > > > unsigned long pasid; > > > struct iommu_domain *domain; > > > struct device *dev = mdev_dev(mdev); > > > struct device *iommu_device = vfio_mdev_get_iommu_device(dev); > > > > > > domain = iommu_aux_get_domain_for_dev(dev); > > > if (!domain) > > > return -ENODEV; > > > > > > pasid = iommu_aux_get_pasid(domain, iommu_device); > > > if (pasid <= 0) > > > return -EINVAL; > > > > > > /* Program the device context */ > > > .... > > > > > > This adds an API for such use case. > > > > > > Suggested-by: Alex Williamson > > > Signed-off-by: Lu Baolu > > > --- > > > drivers/iommu/iommu.c | 18 ++++++++++++++++++ > > > include/linux/iommu.h | 7 +++++++ > > > 2 files changed, 25 insertions(+) > > > > > > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c > > > index cad5a19ebf22..434bf42b6b9b 100644 > > > --- a/drivers/iommu/iommu.c > > > +++ b/drivers/iommu/iommu.c > > > @@ -2817,6 +2817,24 @@ void iommu_aux_detach_group(struct > > iommu_domain *domain, > > > } > > > EXPORT_SYMBOL_GPL(iommu_aux_detach_group); > > > > > > +struct iommu_domain *iommu_aux_get_domain_for_dev(struct device > > *dev) > > > +{ > > > + struct iommu_domain *domain = NULL; > > > + struct iommu_group *group; > > > + > > > + group = iommu_group_get(dev); > > > + if (!group) > > > + return NULL; > > > + > > > + if (group->aux_domain_attached) > > > + domain = group->domain; > > > > Why wouldn't the aux domain flag be on the domain itself rather than > > the group? Then if we wanted sanity checking in patch 1/ we'd only > > need to test the flag on the object we're provided. > > > > If we had such a flag, we could create an iommu_domain_is_aux() > > function and then simply use iommu_get_domain_for_dev() and test that > > it's an aux domain in the example use case. It seems like that would > > IOMMU layer manages domains per parent device. Here given a Is this the IOMMU layer or the VT-d driver? I don't see any notion of managing domains relative to a parent in the IOMMU layer. Please point to something more specific if I'm wrong here. > dev (of mdev), we need a way to find its associated domain under its > parent device. And we cannot simply use iommu_get_domain_for_dev > on the parent device of the mdev, as it will give us the primary domain > of parent device. Not the parent device of the mdev, but the mdev_dev(mdev) device. Isn't that what this series is enabling, being able to return the domain from the group that contains the mdev_dev? We shouldn't need to leave breadcrumbs on the group to know about the domain, the domain itself should be the source of knowledge, or provide a mechanism/ops to learn that knowledge. Thanks, Alex > > resolve the jump from a domain to an aux-domain just as well as adding > > this separate iommu_aux_get_domain_for_dev() interface. The is_aux > > test might also be useful in other cases too. Thanks, > > > > Alex > > > > > + > > > + iommu_group_put(group); > > > + > > > + return domain; > > > +} > > > +EXPORT_SYMBOL_GPL(iommu_aux_get_domain_for_dev); > > > + > > > /** > > > * iommu_sva_bind_device() - Bind a process address space to a device > > > * @dev: the device > > > diff --git a/include/linux/iommu.h b/include/linux/iommu.h > > > index 9506551139ab..cda6cef7579e 100644 > > > --- a/include/linux/iommu.h > > > +++ b/include/linux/iommu.h > > > @@ -639,6 +639,7 @@ int iommu_aux_attach_group(struct > > iommu_domain *domain, > > > struct iommu_group *group, struct device *dev); > > > void iommu_aux_detach_group(struct iommu_domain *domain, > > > struct iommu_group *group, struct device *dev); > > > +struct iommu_domain *iommu_aux_get_domain_for_dev(struct device > > *dev); > > > > > > struct iommu_sva *iommu_sva_bind_device(struct device *dev, > > > struct mm_struct *mm, > > > @@ -1040,6 +1041,12 @@ iommu_aux_detach_group(struct > > iommu_domain *domain, > > > { > > > } > > > > > > +static inline struct iommu_domain * > > > +iommu_aux_get_domain_for_dev(struct device *dev) > > > +{ > > > + return NULL; > > > +} > > > + > > > static inline struct iommu_sva * > > > iommu_sva_bind_device(struct device *dev, struct mm_struct *mm, void > > *drvdata) > > > { > _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu