smmu 学习笔记之domain_alloc

2019-11-07 23:41:40

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smmu提供iommu_domain_alloc 这个接口来申请iommu_domain，举例如下：void 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");}可见iommu_domain_alloc只有一个形参，这个形参是bus_typestruct iommu_domain *iommu_domain_alloc(struct bus_type *bus){ return __iommu_domain_alloc(bus, IOMMU_DOMAIN_UNMANAGED);}增加type后调用__iommu_domain_allocstatic struct iommu_domain *__iommu_domain_alloc(struct bus_type *bus, unsigned type){ struct iommu_domain *domain; //判断bus和bus->iommu_ops 不能为null后 if (bus == NULL || bus->iommu_ops == NULL) return NULL; //调用bus->iommu_ops->domain_alloc 申请domain domain = bus->iommu_ops->domain_alloc(type); if (!domain) return NULL;//给domain的ops赋值为bus->iommu_ops domain->ops = bus->iommu_ops; domain->type = type; /* Assume all sizes by default; the driver may override this later */ domain->pgsize_bitmap = bus->iommu_ops->pgsize_bitmap; return domain;}我们继续看bus->iommu_ops->domain_alloc。在arm_smmu_device_probe 函数中会给bus的iommu_ops 赋值#ifdef CONFIG_PCI if (pci_bus_type.iommu_ops != &arm_smmu_ops) { pci_request_acs(); ret = bus_set_iommu(&pci_bus_type, &arm_smmu_ops); if (ret) return ret; }#endif#ifdef CONFIG_ARM_AMBA if (amba_bustype.iommu_ops != &arm_smmu_ops) { ret = bus_set_iommu(&amba_bustype, &arm_smmu_ops); if (ret) return ret; }#endif if (platform_bus_type.iommu_ops != &arm_smmu_ops) { ret = bus_set_iommu(&platform_bus_type, &arm_smmu_ops); if (ret) return ret; }可见总共支持三种总线。从bus_set_iommu 中就可以看到是将arm_smmu_ops 赋值给bus->iommu_opsint bus_set_iommu(struct bus_type *bus, const struct iommu_ops *ops){ int err; if (bus->iommu_ops != NULL) return -EBUSY; bus->iommu_ops = ops; /* Do IOMMU specific setup for this bus-type */ err = iommu_bus_init(bus, ops); if (err) bus->iommu_ops = NULL; return err;}因此__iommu_domain_alloc 中的bus->iommu_ops->domain_alloc 就等于arm_smmu_ops->domain_alloc而arm_smmu_ops->domain_alloc = arm_smmu_domain_allocstatic struct iommu_domain *arm_smmu_domain_alloc(unsigned type){ struct arm_smmu_domain *smmu_domain;//从arm_smmu_domain_alloc 中可以看出type 只能是IOMMU_DOMAIN_UNMANAGED 和 IOMMU_DOMAIN_DMA if (type != IOMMU_DOMAIN_UNMANAGED && type != IOMMU_DOMAIN_DMA) return NULL; /* * Allocate the domain and initialise some of its data structures. * We can't really do anything meaningful until we've added a * master. *///调用kzalloc 来申请arm_smmu_domain结构 smmu_domain = kzalloc(sizeof(*smmu_domain), GFP_KERNEL); if (!smmu_domain) return NULL;//如果type == IOMMU_DOMAIN_DMA的话，还要申请cookie if (type == IOMMU_DOMAIN_DMA && iommu_get_dma_cookie(&smmu_domain->domain)) { kfree(smmu_domain); return NULL; } mutex_init(&smmu_domain->init_mutex); spin_lock_init(&smmu_domain->pgtbl_lock); return &smmu_domain->domain;}int iommu_get_dma_cookie(struct iommu_domain *domain){ struct iommu_dma_cookie *cookie; if (domain->iova_cookie) return -EEXIST; cookie = kzalloc(sizeof(*cookie), GFP_KERNEL); if (!cookie) return -ENOMEM; spin_lock_init(&cookie->msi_lock); INIT_LIST_HEAD(&cookie->msi_page_list); domain->iova_cookie = cookie; return 0;}iommu_get_dma_cookie 也只是简单的申请memory和赋值而已。

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