Messages in this thread | | | Subject | Re: [PATCH 1/2] iommu: Add iommu_group_get/set_domain() | From | Robin Murphy <> | Date | Mon, 29 Jun 2020 12:56:46 +0100 |
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On 2020-06-27 04:15, Lu Baolu wrote: > The hardware assistant vfio mediated device is a use case of iommu > aux-domain. The interactions between vfio/mdev and iommu during mdev > creation and passthr are: > > - Create a group for mdev with iommu_group_alloc(); > - Add the device to the group with > group = iommu_group_alloc(); > if (IS_ERR(group)) > return PTR_ERR(group); > > ret = iommu_group_add_device(group, &mdev->dev); > if (!ret) > dev_info(&mdev->dev, "MDEV: group_id = %d\n", > iommu_group_id(group)); > - Allocate an aux-domain > iommu_domain_alloc() > - Attach the aux-domain to the physical device from which the mdev is > created. > iommu_aux_attach_device() > > In the whole process, an iommu group was allocated for the mdev and an > iommu domain was attached to the group, but the group->domain leaves > NULL. As the result, iommu_get_domain_for_dev() doesn't work anymore. > > This adds iommu_group_get/set_domain() so that group->domain could be > managed whenever a domain is attached or detached through the aux-domain > api's.
Letting external callers poke around directly in the internals of iommu_group doesn't look right to me.
If a regular device is attached to one or more aux domains for PASID use, iommu_get_domain_for_dev() is still going to return the primary domain, so why should it be expected to behave differently for mediated devices? AFAICS it's perfectly legitimate to have no primary domain if traffic-without-PASID is invalid.
Robin.
> Fixes: 7bd50f0cd2fd5 ("vfio/type1: Add domain at(de)taching group helpers") > Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com> > --- > drivers/iommu/iommu.c | 28 ++++++++++++++++++++++++++++ > include/linux/iommu.h | 14 ++++++++++++++ > 2 files changed, 42 insertions(+) > > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c > index d43120eb1dc5..e2b665303d70 100644 > --- a/drivers/iommu/iommu.c > +++ b/drivers/iommu/iommu.c > @@ -715,6 +715,34 @@ int iommu_group_set_name(struct iommu_group *group, const char *name) > } > EXPORT_SYMBOL_GPL(iommu_group_set_name); > > +/** > + * iommu_group_get_domain - get domain of a group > + * @group: the group > + * > + * This is called to get the domain of a group. > + */ > +struct iommu_domain *iommu_group_get_domain(struct iommu_group *group) > +{ > + return group->domain; > +} > +EXPORT_SYMBOL_GPL(iommu_group_get_domain); > + > +/** > + * iommu_group_set_domain - set domain for a group > + * @group: the group > + * @domain: iommu domain > + * > + * This is called to set the domain for a group. In aux-domain case, a domain > + * might attach or detach to an iommu group through the aux-domain apis, but > + * the group->domain doesn't get a chance to be updated there. > + */ > +void iommu_group_set_domain(struct iommu_group *group, > + struct iommu_domain *domain) > +{ > + group->domain = domain; > +} > +EXPORT_SYMBOL_GPL(iommu_group_set_domain); > + > static int iommu_create_device_direct_mappings(struct iommu_group *group, > struct device *dev) > { > diff --git a/include/linux/iommu.h b/include/linux/iommu.h > index 5f0b7859d2eb..ff88d548a870 100644 > --- a/include/linux/iommu.h > +++ b/include/linux/iommu.h > @@ -496,6 +496,9 @@ extern void iommu_group_set_iommudata(struct iommu_group *group, > void *iommu_data, > void (*release)(void *iommu_data)); > extern int iommu_group_set_name(struct iommu_group *group, const char *name); > +extern struct iommu_domain *iommu_group_get_domain(struct iommu_group *group); > +extern void iommu_group_set_domain(struct iommu_group *group, > + struct iommu_domain *domain); > extern int iommu_group_add_device(struct iommu_group *group, > struct device *dev); > extern void iommu_group_remove_device(struct device *dev); > @@ -840,6 +843,17 @@ static inline int iommu_group_set_name(struct iommu_group *group, > return -ENODEV; > } > > +static inline > +struct iommu_domain *iommu_group_get_domain(struct iommu_group *group) > +{ > + return NULL; > +} > + > +static inline void iommu_group_set_domain(struct iommu_group *group, > + struct iommu_domain *domain) > +{ > +} > + > static inline int iommu_group_add_device(struct iommu_group *group, > struct device *dev) > { >
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