Re: [PATCH RFC v1 13/15] iommu/virtio: Attach Arm PASID tables when available

Jean-Philippe Brucker
2021-03-03T20:56:08Z

On Fri, Jan 15, 2021 at 05:43:40PM +0530, Vivek Gautam wrote:
[...]
> +static int viommu_setup_pgtable(struct viommu_endpoint *vdev,
> + struct viommu_domain *vdomain)
> +{
> + int ret, id;
> + u32 asid;
> + enum io_pgtable_fmt fmt;
> + struct io_pgtable_ops *ops = NULL;
> + struct viommu_dev *viommu = vdev->viommu;
> + struct virtio_iommu_probe_table_format *desc = vdev->pgtf;
> + struct iommu_pasid_table *tbl = vdomain->pasid_tbl;
> + struct iommu_vendor_psdtable_cfg *pst_cfg;
> + struct arm_smmu_cfg_info *cfgi;
> + struct io_pgtable_cfg cfg = {
> + .iommu_dev = viommu->dev->parent,
> + .tlb = &viommu_flush_ops,
> + .pgsize_bitmap = vdev->pgsize_mask ? vdev->pgsize_mask :
> + vdomain->domain.pgsize_bitmap,
> + .ias = (vdev->input_end ? ilog2(vdev->input_end) :
> + ilog2(vdomain->domain.geometry.aperture_end)) + 1,
> + .oas = vdev->output_bits,
> + };
> +
> + if (!desc)
> + return -EINVAL;
> +
> + if (!vdev->output_bits)
> + return -ENODEV;
> +
> + switch (le16_to_cpu(desc->format)) {
> + case VIRTIO_IOMMU_FOMRAT_PGTF_ARM_LPAE:
> + fmt = ARM_64_LPAE_S1;
> + break;
> + default:
> + dev_err(vdev->dev, "unsupported page table format 0x%x\n",
> + le16_to_cpu(desc->format));
> + return -EINVAL;
> + }
> +
> + if (vdomain->mm.ops) {
> + /*
> + * TODO: attach additional endpoint to the domain. Check that
> + * the config is sane.
> + */
> + return -EEXIST;
> + }
> +
> + vdomain->mm.domain = vdomain;
> + ops = alloc_io_pgtable_ops(fmt, &cfg, &vdomain->mm);
> + if (!ops)
> + return -ENOMEM;
> +
> + pst_cfg = &tbl->cfg;
> + cfgi = &pst_cfg->vendor.cfg;
> + id = ida_simple_get(&asid_ida, 1, 1 << desc->asid_bits, GFP_KERNEL);
> + if (id < 0) {
> + ret = id;
> + goto err_free_pgtable;
> + }
> +
> + asid = id;
> + ret = iommu_psdtable_prepare(tbl, pst_cfg, &cfg, asid);
> + if (ret)
> + goto err_free_asid;
> +
> + /*
> + * Strange to setup an op here?
> + * cd-lib is the actual user of sync op, and therefore the platform
> + * drivers should assign this sync/maintenance ops as per need.
> + */
> + tbl->ops->sync = viommu_flush_pasid;

But this function deals with page tables, not pasid tables. As said on an
earlier patch, the TLB flush ops should probably be passed during table
registration - those ops are global so should really be const.

> +
> + /* Right now only PASID 0 supported ?? */
> + ret = iommu_psdtable_write(tbl, pst_cfg, 0, &cfgi->s1_cfg->cd);
> + if (ret)
> + goto err_free_asid;
> +
> + vdomain->mm.ops = ops;
> + dev_dbg(vdev->dev, "using page table format 0x%x\n", fmt);
> +
> + return 0;
> +
> +err_free_asid:
> + ida_simple_remove(&asid_ida, asid);
> +err_free_pgtable:
> + free_io_pgtable_ops(ops);
> + return ret;
> +}
> +
> +static int viommu_config_arm_pst(struct iommu_vendor_psdtable_cfg *pst_cfg,
> + struct virtio_iommu_req_attach_pst_arm *req)
> +{
> + struct arm_smmu_s1_cfg *s1_cfg = pst_cfg->vendor.cfg.s1_cfg;
> +
> + if (!s1_cfg)
> + return -ENODEV;
> +
> + req->format = cpu_to_le16(VIRTIO_IOMMU_FORMAT_PSTF_ARM_SMMU_V3);
> + req->s1fmt = s1_cfg->s1fmt;
> + req->s1dss = VIRTIO_IOMMU_PSTF_ARM_SMMU_V3_DSS_0;
> + req->s1contextptr = cpu_to_le64(pst_cfg->base);
> + req->s1cdmax = cpu_to_le32(s1_cfg->s1cdmax);
> +
> + return 0;
> +}
> +
> +static int viommu_config_pst(struct iommu_vendor_psdtable_cfg *pst_cfg,
> + void *req, enum pasid_table_fmt fmt)
> +{
> + int ret;
> +
> + switch (fmt) {
> + case PASID_TABLE_ARM_SMMU_V3:
> + ret = viommu_config_arm_pst(pst_cfg, req);
> + break;
> + default:
> + ret = -EINVAL;
> + WARN_ON(1);
> + }
> +
> + return ret;
> +}
> +
> +static int viommu_prepare_arm_pst(struct viommu_endpoint *vdev,
> + struct iommu_vendor_psdtable_cfg *pst_cfg)
> +{
> + struct virtio_iommu_probe_table_format *pgtf = vdev->pgtf;
> + struct arm_smmu_cfg_info *cfgi = &pst_cfg->vendor.cfg;
> + struct arm_smmu_s1_cfg *cfg;
> +
> + /* Some sanity checks */
> + if (pgtf->asid_bits != 8 && pgtf->asid_bits != 16)
> + return -EINVAL;

No need for this, next patch cheks asid size in viommu_config_arm_pgt()

> +
> + cfg = devm_kzalloc(pst_cfg->iommu_dev, sizeof(cfg), GFP_KERNEL);
> + if (!cfg)
> + return -ENOMEM;
> +
> + cfgi->s1_cfg = cfg;
> + cfg->s1cdmax = vdev->pasid_bits;
> + cfg->cd.asid = pgtf->asid_bits;

That doesn't look right, cfg->cd.asid takes the ASID value of context 0
but here we're writing a limit. viommu_setup_pgtable() probably needs to
set this field to the allocated ASID, since viommu_teardown_pgtable() uses
it.

> +
> + pst_cfg->fmt = PASID_TABLE_ARM_SMMU_V3;

Parent function can set this

> + /* XXX HACK: set feature bit ARM_SMMU_FEAT_2_LVL_CDTAB */
> + pst_cfg->vendor.cfg.feat_flag |= (1 << 1);

Oh right, this flag is missing. I'll add

#define VIRTIO_IOMMU_PST_ARM_SMMU3_F_CD2L (1ULL << 1)

to the spec.

> +
> + return 0;
> +}
> +
> +static int viommu_prepare_pst(struct viommu_endpoint *vdev,
> + struct iommu_vendor_psdtable_cfg *pst_cfg,
> + enum pasid_table_fmt fmt)
> +{
> + int ret;
> +
> + switch (fmt) {
> + case PASID_TABLE_ARM_SMMU_V3:
> + ret = viommu_prepare_arm_pst(vdev, pst_cfg);
> + break;
> + default:
> + dev_err(vdev->dev, "unsupported PASID table format 0x%x\n", fmt);
> + ret = -EINVAL;
> + }
> +
> + return ret;
> +}
> +
> +static int viommu_attach_pasid_table(struct viommu_endpoint *vdev,
> + struct viommu_domain *vdomain)
> +{
> + int ret;
> + int i, eid;
> + enum pasid_table_fmt fmt = -1;
> + struct virtio_iommu_probe_table_format *desc = vdev->pstf;
> + struct virtio_iommu_req_attach_table req = {
> + .head.type = VIRTIO_IOMMU_T_ATTACH_TABLE,
> + .domain = cpu_to_le32(vdomain->id),
> + };
> + struct viommu_dev *viommu = vdev->viommu;
> + struct iommu_pasid_table *tbl;
> + struct iommu_vendor_psdtable_cfg *pst_cfg;
> +
> + if (!viommu->has_table)
> + return 0;
> +
> + if (!desc)
> + return -ENODEV;
> +
> + /* Prepare PASID tables configuration */
> + switch (le16_to_cpu(desc->format)) {
> + case VIRTIO_IOMMU_FORMAT_PSTF_ARM_SMMU_V3:
> + fmt = PASID_TABLE_ARM_SMMU_V3;
> + break;
> + default:
> + dev_err(vdev->dev, "unsupported PASID table format 0x%x\n",
> + le16_to_cpu(desc->format));
> + return 0;
> + }
> +
> + if (!tbl) {
> + tbl = iommu_register_pasid_table(fmt, viommu->dev->parent, vdomain);
> + if (!tbl)
> + return -ENOMEM;
> +
> + vdomain->pasid_tbl = tbl;
> + pst_cfg = &tbl->cfg;
> +
> + pst_cfg->iommu_dev = viommu->dev->parent;
> +
> + /* Prepare PASID tables info to allocate a new table */
> + ret = viommu_prepare_pst(vdev, pst_cfg, fmt);
> + if (ret)
> + return ret;
> +
> + ret = iommu_psdtable_alloc(tbl, pst_cfg);
> + if (ret)
> + return ret;
> +
> + pst_cfg->iommu_dev = viommu->dev->parent;

Already set by iommu_register_pasid_table() (and needed for DMA
allocations in iommu_psdtable_alloc())

> + pst_cfg->fmt = PASID_TABLE_ARM_SMMU_V3;

Already set above

> +
> + ret = viommu_setup_pgtable(vdev, vdomain);
> + if (ret) {
> + dev_err(vdev->dev, "could not install page tables\n");
> + goto err_free_psdtable;
> + }
> +
> + /* Add arch-specific configuration */
> + ret = viommu_config_pst(pst_cfg, (void *)&req, fmt);
> + if (ret)
> + goto err_free_ops;
> +
> + vdev_for_each_id(i, eid, vdev) {
> + req.endpoint = cpu_to_le32(eid);
> + ret = viommu_send_req_sync(viommu, &req, sizeof(req));
> + if (ret)
> + goto err_free_ops;
> + }
> + } else {
> + /* TODO: otherwise, check for compatibility with vdev. */
> + return -ENOSYS;
> + }
> +
> + dev_dbg(vdev->dev, "uses PASID table format 0x%x\n", fmt);
> +
> + return 0;
> +
> +err_free_ops:
> + if (vdomain->mm.ops)
> + viommu_teardown_pgtable(vdomain);
> +err_free_psdtable:
> + iommu_psdtable_free(tbl, &tbl->cfg);
> +
> + return ret;
> +}
> +
> static int viommu_attach_dev(struct iommu_domain *domain, struct device *dev)
> {
> int ret = 0;
> @@ -928,6 +1213,17 @@ static int viommu_attach_dev(struct iommu_domain *domain, struct device *dev)
> if (vdev->vdomain)
> vdev->vdomain->nr_endpoints--;
>
> + ret = viommu_attach_pasid_table(vdev, vdomain);
> + if (ret) {
> + /*
> + * No PASID support, too bad. Perhaps we can bind a single set
> + * of page tables?
> + */
> + ret = viommu_setup_pgtable(vdev, vdomain);

This cannot work at the moment because viommu_setup_pgtable() writes to
the non-existing pasid table. Probably best to leave this call for next
patch.

Thanks,
Jean

> + if (ret)
> + dev_err(vdev->dev, "could not install tables\n");
> + }
> +
> if (!vdomain->mm.ops) {
> /* If we couldn't bind any table, use the mapping tree */
> ret = viommu_simple_attach(vdomain, vdev);
> @@ -948,6 +1244,10 @@ static int viommu_map(struct iommu_domain *domain, unsigned long iova,
> u32 flags;
> struct virtio_iommu_req_map map;
> struct viommu_domain *vdomain = to_viommu_domain(domain);
> + struct io_pgtable_ops *ops = vdomain->mm.ops;
> +
> + if (ops)
> + return ops->map(ops, iova, paddr, size, prot, gfp);
>
> flags = (prot & IOMMU_READ ? VIRTIO_IOMMU_MAP_F_READ : 0) |
> (prot & IOMMU_WRITE ? VIRTIO_IOMMU_MAP_F_WRITE : 0) |
> @@ -986,6 +1286,10 @@ static size_t viommu_unmap(struct iommu_domain *domain, unsigned long iova,
> size_t unmapped;
> struct virtio_iommu_req_unmap unmap;
> struct viommu_domain *vdomain = to_viommu_domain(domain);
> + struct io_pgtable_ops *ops = vdomain->mm.ops;
> +
> + if (ops)
> + return ops->unmap(ops, iova, size, gather);
>
> unmapped = viommu_del_mappings(vdomain, iova, size);
> if (unmapped < size)
> @@ -1014,6 +1318,10 @@ static phys_addr_t viommu_iova_to_phys(struct iommu_domain *domain,
> struct viommu_mapping *mapping;
> struct interval_tree_node *node;
> struct viommu_domain *vdomain = to_viommu_domain(domain);
> + struct io_pgtable_ops *ops = vdomain->mm.ops;
> +
> + if (ops)
> + return ops->iova_to_phys(ops, iova);
>
> spin_lock_irqsave(&vdomain->mappings_lock, flags);
> node = interval_tree_iter_first(&vdomain->mappings, iova, iova);
> @@ -1264,7 +1572,12 @@ static int viommu_probe(struct virtio_device *vdev)
> struct virtio_iommu_config, probe_size,
> &viommu->probe_size);
>
> + viommu->has_table = virtio_has_feature(vdev, VIRTIO_IOMMU_F_ATTACH_TABLE);
> viommu->has_map = virtio_has_feature(vdev, VIRTIO_IOMMU_F_MAP_UNMAP);
> + if (!viommu->has_table && !viommu->has_map) {
> + ret = -EINVAL;
> + goto err_free_vqs;
> + }
>
> viommu->geometry = (struct iommu_domain_geometry) {
> .aperture_start = input_start,
> @@ -1356,6 +1669,7 @@ static unsigned int features[] = {
> VIRTIO_IOMMU_F_DOMAIN_RANGE,
> VIRTIO_IOMMU_F_PROBE,
> VIRTIO_IOMMU_F_MMIO,
> + VIRTIO_IOMMU_F_ATTACH_TABLE,
> };
>
> static struct virtio_device_id id_table[] = {
> --
> 2.17.1
>