The iommu_attach/detach_device() interfaces were exposed for the device
drivers to attach/detach their own domains. The commit <426a273834eae>
("iommu: Limit iommu_attach/detach_device to device with their own group")
restricted them to singleton groups to avoid different device in a group
attaching different domain.As we've introduced device DMA ownership into the iommu core. We can now introduce interfaces for muliple-device groups, and "all devices are in the same address space" is still guaranteed. The iommu_attach/detach_device_shared() could be used when multiple drivers sharing the group claim the DMA_OWNER_PRIVATE_DOMAIN ownership. The first call of iommu_attach_device_shared() attaches the domain to the group. Other drivers could join it later. The domain will be detached from the group after all drivers unjoin it. Signed-off-by: Jason Gunthorpe <[email protected]> Signed-off-by: Lu Baolu <[email protected]> Tested-by: Dmitry Osipenko <[email protected]> --- include/linux/iommu.h | 13 +++++++ drivers/iommu/iommu.c | 79 +++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 92 insertions(+) diff --git a/include/linux/iommu.h b/include/linux/iommu.h index 5ad4cf13370d..1bc03118dfb3 100644 --- a/include/linux/iommu.h +++ b/include/linux/iommu.h @@ -703,6 +703,8 @@ int iommu_group_set_dma_owner(struct iommu_group *group, enum iommu_dma_owner ow void *owner_cookie); void iommu_group_release_dma_owner(struct iommu_group *group, enum iommu_dma_owner owner); bool iommu_group_dma_owner_unclaimed(struct iommu_group *group); +int iommu_attach_device_shared(struct iommu_domain *domain, struct device *dev); +void iommu_detach_device_shared(struct iommu_domain *domain, struct device *dev); #else /* CONFIG_IOMMU_API */ @@ -743,11 +745,22 @@ static inline int iommu_attach_device(struct iommu_domain *domain, return -ENODEV; } +static inline int iommu_attach_device_shared(struct iommu_domain *domain, + struct device *dev) +{ + return -ENODEV; +} + static inline void iommu_detach_device(struct iommu_domain *domain, struct device *dev) { } +static inline void iommu_detach_device_shared(struct iommu_domain *domain, + struct device *dev) +{ +} + static inline struct iommu_domain *iommu_get_domain_for_dev(struct device *dev) { return NULL; diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index 8bec71b1cc18..3ad66cb9bedc 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -50,6 +50,7 @@ struct iommu_group { struct list_head entry; enum iommu_dma_owner dma_owner; unsigned int owner_cnt; + unsigned int attach_cnt; void *owner_cookie; }; @@ -3512,3 +3513,81 @@ void iommu_device_release_dma_owner(struct device *dev, enum iommu_dma_owner own iommu_group_put(group); } EXPORT_SYMBOL_GPL(iommu_device_release_dma_owner); + +/** + * iommu_attach_device_shared() - Attach shared domain to a device + * @domain: The shared domain. + * @dev: The device. + * + * Similar to iommu_attach_device(), but allowed for shared-group devices + * and guarantees that all devices in an iommu group could only be attached + * by a same iommu domain. The caller should explicitly set the dma ownership + * of DMA_OWNER_PRIVATE_DOMAIN or DMA_OWNER_PRIVATE_DOMAIN_USER type before + * calling it and use the paired helper iommu_detach_device_shared() for + * cleanup. + */ +int iommu_attach_device_shared(struct iommu_domain *domain, struct device *dev) +{ + struct iommu_group *group; + int ret = 0; + + group = iommu_group_get(dev); + if (!group) + return -ENODEV; + + mutex_lock(&group->mutex); + if (group->dma_owner != DMA_OWNER_PRIVATE_DOMAIN && + group->dma_owner != DMA_OWNER_PRIVATE_DOMAIN_USER) { + ret = -EPERM; + goto unlock_out; + } + + if (group->attach_cnt) { + if (group->domain != domain) { + ret = -EBUSY; + goto unlock_out; + } + } else { + ret = __iommu_attach_group(domain, group); + if (ret) + goto unlock_out; + } + + group->attach_cnt++; +unlock_out: + mutex_unlock(&group->mutex); + iommu_group_put(group); + + return ret; +} +EXPORT_SYMBOL_GPL(iommu_attach_device_shared); + +/** + * iommu_detach_device_shared() - Detach a domain from device + * @domain: The domain. + * @dev: The device. + * + * The detach helper paired with iommu_attach_device_shared(). + */ +void iommu_detach_device_shared(struct iommu_domain *domain, struct device *dev) +{ + struct iommu_group *group; + + group = iommu_group_get(dev); + if (!group) + return; + + mutex_lock(&group->mutex); + if (WARN_ON(!group->attach_cnt || group->domain != domain || + (group->dma_owner != DMA_OWNER_PRIVATE_DOMAIN && + group->dma_owner != DMA_OWNER_PRIVATE_DOMAIN_USER))) + goto unlock_out; + + if (--group->attach_cnt == 0) + __iommu_detach_group(domain, group); + +unlock_out: + mutex_unlock(&group->mutex); + iommu_group_put(group); +} +EXPORT_SYMBOL_GPL(iommu_detach_device_shared); -- 2.25.1 _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
