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 extend these interfaces for muliple-device groups, and "all devices are in the same address space" is still guaranteed. For multiple devices belonging to a same group, iommu_device_use_dma_api() and iommu_attach_device() are exclusive. Therefore, when drivers decide to use iommu_attach_domain(), they cannot call iommu_device_use_dma_api() at the same time. Signed-off-by: Jason Gunthorpe <[email protected]> Signed-off-by: Lu Baolu <[email protected]> --- drivers/iommu/iommu.c | 79 +++++++++++++++++++++++++++++++++---------- 1 file changed, 62 insertions(+), 17 deletions(-) diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index ab8ab95969f5..2c9efd85e447 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -47,6 +47,7 @@ struct iommu_group { struct iommu_domain *domain; struct list_head entry; unsigned int owner_cnt; + unsigned int attach_cnt; void *owner; }; @@ -1921,27 +1922,59 @@ static int __iommu_attach_device(struct iommu_domain *domain, return ret; } +/** + * iommu_attach_device() - attach external or UNMANAGED domain to device + * @domain: the domain about to attach + * @dev: the device about to be attached + * + * For devices belonging to the same group, iommu_device_use_dma_api() and + * iommu_attach_device() are exclusive. Therefore, when drivers decide to + * use iommu_attach_domain(), they cannot call iommu_device_use_dma_api() + * at the same time. + */ int iommu_attach_device(struct iommu_domain *domain, struct device *dev) { struct iommu_group *group; - int ret; + int ret = 0; + + if (domain->type != IOMMU_DOMAIN_UNMANAGED) + return -EINVAL; group = iommu_group_get(dev); if (!group) return -ENODEV; - /* - * Lock the group to make sure the device-count doesn't - * change while we are attaching - */ mutex_lock(&group->mutex); - ret = -EINVAL; - if (iommu_group_device_count(group) != 1) - goto out_unlock; + if (group->owner_cnt) { + /* + * Group has been used for kernel-api dma or claimed explicitly + * for exclusive occupation. For backward compatibility, device + * in a singleton group is allowed to ignore setting the + * drv.no_kernel_api_dma field. + */ + if ((group->domain == group->default_domain && + iommu_group_device_count(group) != 1) || + group->owner) { + ret = -EBUSY; + goto unlock_out; + } + } - ret = __iommu_attach_group(domain, group); + if (!group->attach_cnt) { + ret = __iommu_attach_group(domain, group); + if (ret) + goto unlock_out; + } else { + if (group->domain != domain) { + ret = -EPERM; + goto unlock_out; + } + } -out_unlock: + group->owner_cnt++; + group->attach_cnt++; + +unlock_out: mutex_unlock(&group->mutex); iommu_group_put(group); @@ -2182,23 +2215,35 @@ static void __iommu_detach_device(struct iommu_domain *domain, trace_detach_device_from_domain(dev); } +/** + * iommu_detach_device() - detach external or UNMANAGED domain from device + * @domain: the domain about to detach + * @dev: the device about to be detached + * + * Paired with iommu_attach_device(), it detaches the domain from the device. + */ void iommu_detach_device(struct iommu_domain *domain, struct device *dev) { struct iommu_group *group; + if (WARN_ON(domain->type != IOMMU_DOMAIN_UNMANAGED)) + return; + group = iommu_group_get(dev); - if (!group) + if (WARN_ON(!group)) return; mutex_lock(&group->mutex); - if (iommu_group_device_count(group) != 1) { - WARN_ON(1); - goto out_unlock; - } + if (WARN_ON(!group->attach_cnt || !group->owner_cnt || + group->domain != domain)) + goto unlock_out; - __iommu_detach_group(domain, group); + group->attach_cnt--; + group->owner_cnt--; + if (!group->attach_cnt) + __iommu_detach_group(domain, group); -out_unlock: +unlock_out: mutex_unlock(&group->mutex); iommu_group_put(group); } -- 2.25.1 _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
