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...@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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