smmu 学习笔记之attach_dev 2

2019-11-07 23:34:53

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static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev){ int ret = 0; struct arm_smmu_device *smmu;//从iommu_domain 中得到arm_smmu_domain struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain); struct arm_smmu_master_data *master; struct arm_smmu_strtab_ent *ste; if (!dev->iommu_fwspec) return -ENOENT; master = dev->iommu_fwspec->iommu_PRiv; smmu = master->smmu; ste = &master->ste; /* Already attached to a different domain? *///ste->bypass 不为null的话，说明arm_smmu_attach_dev 已经被调用过了，这个值是在arm_smmu_attach_dev 后面赋值的 if (!ste->bypass) arm_smmu_detach_dev(dev); mutex_lock(&smmu_domain->init_mutex);//一般情况下smmu_domain->smmu 也就是arm_smmu_device 是等于null的 if (!smmu_domain->smmu) { smmu_domain->smmu = smmu; ret = arm_smmu_domain_finalise(domain); if (ret) { smmu_domain->smmu = NULL; goto out_unlock; } } else if (smmu_domain->smmu != smmu) { dev_err(dev, "cannot attach to SMMU %s (upstream of %s)/n", dev_name(smmu_domain->smmu->dev), dev_name(smmu->dev)); ret = -ENXIO; goto out_unlock; }//给ste->bypass 赋值，前面已经判断了 ste->bypass = false; ste->valid = true;//smmu的stage分为两部分，s1和s2，s1是从va->ipa,而s2是从ipa->pa.va 表示虚拟地址，ipa表示中间物理地址，pa表示物理地址.//如果stage 是s1的话，就说明是虚拟化应用，需要配置s1， if (smmu_domain->stage == ARM_SMMU_DOMAIN_S1) { ste->s1_cfg = &smmu_domain->s1_cfg; ste->s2_cfg = NULL; arm_smmu_write_ctx_desc(smmu, ste->s1_cfg); } else { ste->s1_cfg = NULL; ste->s2_cfg = &smmu_domain->s2_cfg; }//从这段code看每个domain中只能包含s1或者s2，不能同时包含.也就是说如果要从va->ipa->pa的话，就必须要两个domain.//初始化ste table ret = arm_smmu_install_ste_for_dev(dev->iommu_fwspec); if (ret < 0) ste->valid = false;out_unlock: mutex_unlock(&smmu_domain->init_mutex); return ret;}继续看看arm_smmu_domain_finalisestatic int arm_smmu_domain_finalise(struct iommu_domain *domain){ int ret; unsigned long ias, oas; enum io_pgtable_fmt fmt; struct io_pgtable_cfg pgtbl_cfg; struct io_pgtable_ops *pgtbl_ops; int (*finalise_stage_fn)(struct arm_smmu_domain *, struct io_pgtable_cfg *); struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain); struct arm_smmu_device *smmu = smmu_domain->smmu; /* Restrict the stage to what we can actually support *///根据当前硬件feature来决定是smmu_domain->stage，这里也可看出domain只能有一个stage.要么是s1要么是s2 if (!(smmu->features & ARM_SMMU_FEAT_TRANS_S1)) smmu_domain->stage = ARM_SMMU_DOMAIN_S2; if (!(smmu->features & ARM_SMMU_FEAT_TRANS_S2)) smmu_domain->stage = ARM_SMMU_DOMAIN_S1; switch (smmu_domain->stage) { case ARM_SMMU_DOMAIN_S1: ias = VA_BITS; oas = smmu->ias; fmt = ARM_64_LPAE_S1; finalise_stage_fn = arm_smmu_domain_finalise_s1; break; case ARM_SMMU_DOMAIN_NESTED: case ARM_SMMU_DOMAIN_S2: ias = smmu->ias; oas = smmu->oas; fmt = ARM_64_LPAE_S2; finalise_stage_fn = arm_smmu_domain_finalise_s2; break; default: return -EINVAL; } pgtbl_cfg = (struct io_pgtable_cfg) { .pgsize_bitmap = smmu->pgsize_bitmap, .ias = ias, .oas = oas, .tlb = &arm_smmu_gather_ops, .iommu_dev = smmu->dev, };//这个地方很重要，注意一下 pgtbl_ops = alloc_io_pgtable_ops(fmt, &pgtbl_cfg, smmu_domain); if (!pgtbl_ops) return -ENOMEM; domain->pgsize_bitmap = pgtbl_cfg.pgsize_bitmap; domain->geometry.aperture_end = (1UL << ias) - 1; domain->geometry.force_aperture = true; smmu_domain->pgtbl_ops = pgtbl_ops;//简单的赋值 ret = finalise_stage_fn(smmu_domain, &pgtbl_cfg); if (ret < 0) free_io_pgtable_ops(pgtbl_ops); return ret;}struct io_pgtable_ops *alloc_io_pgtable_ops(enum io_pgtable_fmt fmt, struct io_pgtable_cfg *cfg, void *cookie){ struct io_pgtable *iop; const struct io_pgtable_init_fns *fns; if (fmt >= IO_PGTABLE_NUM_FMTS) return NULL;//根据fmt来决定fns。fmt 有四种// [ARM_32_LPAE_S1] = &io_pgtable_arm_32_lpae_s1_init_fns,// [ARM_32_LPAE_S2] = &io_pgtable_arm_32_lpae_s2_init_fns,// [ARM_64_LPAE_S1] = &io_pgtable_arm_64_lpae_s1_init_fns,// [ARM_64_LPAE_S2] = &io_pgtable_arm_64_lpae_s2_init_fns, fns = io_pgtable_init_table[fmt]; if (!fns) return NULL; iop = fns->alloc(cfg, cookie); if (!iop) return NULL; iop->fmt = fmt; iop->cookie = cookie; iop->cfg = *cfg; return &iop->ops;}我们以ARM_64_LPAE_S2为例，也就是调用io_pgtable_arm_64_lpae_s2_init_fns的alloc函数struct io_pgtable_init_fns io_pgtable_arm_64_lpae_s2_init_fns = { .alloc = arm_64_lpae_alloc_pgtable_s2, .free = arm_lpae_free_pgtable,};在arm_64_lpae_alloc_pgtable_s2 中最终要就是调用arm_lpae_alloc_pgtable。而arm_lpae_alloc_pgtable中最重要的就是 data->iop.ops = (struct io_pgtable_ops) { .map = arm_lpae_map, .unmap = arm_lpae_unmap, .iova_to_phys = arm_lpae_iova_to_phys, };这段赋值，后面arm_smmu_ops 中调用的map/unmap/iova_to_phys 最终都是调用到这里来

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