smmu 学习笔记之attach_dev

2019-11-07 23:37:33

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根据hns_uio_set_iommu 函数中的flowvoid hns_uio_set_iommu(struct nic_uio_device *PRiv, unsigned long iova, unsigned long paddr, int gfp_order){ struct iommu_domain *domain; int ret = 0; domain = iommu_domain_alloc(priv->dev->bus); if (!domain) PRINT(KERN_ERR, "domain is null/n"); ret = iommu_attach_device(domain, priv->dev); PRINT(KERN_ERR, "domain is null = %d/n", ret); ret = iommu_map(domain, iova, (phys_addr_t)paddr, gfp_order, (IOMMU_WRITE | IOMMU_READ | IOMMU_CACHE)); PRINT(KERN_ERR, "domain is null = %d/n", ret);}申请domain之后，如果domain不为null的话，就要attach deviceint iommu_attach_device(struct iommu_domain *domain, struct device *dev){ struct iommu_group *group; int ret; group = iommu_group_get(dev); /* FIXME: Remove this when groups a mandatory for iommu drivers */ if (group == NULL) return __iommu_attach_device(domain, dev); /* * We have a group - lock it 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; ret = __iommu_attach_group(domain, group);out_unlock: mutex_unlock(&group->mutex); iommu_group_put(group); return ret;}在iommu_attach_device 中首先通过group = iommu_group_get(dev); 得到group在smmu v3版本中的group有两种，其也是在arm_smmu_ops的device_group 中定义的static struct iommu_ops arm_smmu_ops = { .capable = arm_smmu_capable, .domain_alloc = arm_smmu_domain_alloc, .domain_free = arm_smmu_domain_free, .attach_dev = arm_smmu_attach_dev, .map = arm_smmu_map, .unmap = arm_smmu_unmap, .map_sg = default_iommu_map_sg, .iova_to_phys = arm_smmu_iova_to_phys, .add_device = arm_smmu_add_device, .remove_device = arm_smmu_remove_device, .device_group = arm_smmu_device_group, .domain_get_attr = arm_smmu_domain_get_attr, .domain_set_attr = arm_smmu_domain_set_attr, .of_xlate = arm_smmu_of_xlate, .pgsize_bitmap = -1UL, /* Restricted during device attach */};static struct iommu_group *arm_smmu_device_group(struct device *dev){ struct iommu_group *group; /* * We don't support devices sharing stream IDs other than PCI RID * aliases, since the necessary ID-to-device lookup becomes rather * impractical given a potential sparse 32-bit stream ID space. */ if (dev_is_pci(dev)) group = pci_device_group(dev); else group = generic_device_group(dev); return group;}从arm_smmu_device_group 函数可以看出group分为pci group和generic group在iommu_attach_device 函数中我们以generic group为例，如果group为null的话，就调用__iommu_attach_devicestatic int __iommu_attach_device(struct iommu_domain *domain, struct device *dev){ int ret; if (unlikely(domain->ops->attach_dev == NULL)) return -ENODEV; ret = domain->ops->attach_dev(domain, dev); if (!ret) trace_attach_device_to_domain(dev); return ret;}最终也是调用arm_smmu_ops 中的attach_dev 即arm_smmu_attach_dev。这个函数前面已经有介绍了然后在iommu_attach_device 中调用iommu_group_device_count 来看当时是否已经有group了static int iommu_group_device_count(struct iommu_group *group){ struct iommu_device *entry; int ret = 0; list_for_each_entry(entry, &group->devices, list) ret++; return ret;}只要group->devices 不为null，ret 就自加如果最终的group大于1，就调用__iommu_attach_group 来attach groupstatic int __iommu_attach_group(struct iommu_domain *domain, struct iommu_group *group){ int ret; if (group->default_domain && group->domain != group->default_domain) return -EBUSY; ret = __iommu_group_for_each_dev(group, domain, iommu_group_do_attach_device); if (ret == 0) group->domain = domain; return ret;}__iommu_attach_group 中进行参数判断后，继续调用__iommu_group_for_each_dev。如果ret == 0的话，说明执行成功，就将这个申请的domian赋值给group->domain = domain，为每个domain都调用iommu_group_do_attach_devicestatic int iommu_group_do_attach_device(struct device *dev, void *data){ struct iommu_domain *domain = data; return __iommu_attach_device(domain, dev);}继续调用__iommu_attach_devicestatic int __iommu_attach_device(struct iommu_domain *domain, struct device *dev){ int ret; if (unlikely(domain->ops->attach_dev == NULL)) return -ENODEV; ret = domain->ops->attach_dev(domain, dev); if (!ret) trace_attach_device_to_domain(dev); return ret;}最终还是调用domain->ops->attach_dev，最中还是调用arm_smmu_ops 中的attach_dev也就是arm_smmu_attach_dev

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