Message-ID: <ee88590b-513e-7821-ab52-18d496ad90dc@arm.com>
Date:   Fri, 12 Mar 2021 18:59:17 +0530
From:   Vivek Kumar Gautam <vivek.gautam@....com>
To:     Jean-Philippe Brucker <jean-philippe@...aro.org>
Cc:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        iommu@...ts.linux-foundation.org,
        virtualization@...ts.linux-foundation.org, joro@...tes.org,
        will.deacon@....com, mst@...hat.com, robin.murphy@....com,
        eric.auger@...hat.com, alex.williamson@...hat.com,
        kevin.tian@...el.com, jacob.jun.pan@...ux.intel.com,
        yi.l.liu@...el.com, lorenzo.pieralisi@....com,
        shameerali.kolothum.thodi@...wei.com
Subject: Re: [PATCH RFC v1 13/15] iommu/virtio: Attach Arm PASID tables when
 available



On 3/3/21 10:55 PM, Jean-Philippe Brucker wrote:
> 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, will amend it.

> 
>> +
>> +	/* 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()

Right, thanks for catching.

> 
>> +
>> +	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.

Yea, this isn't right. The asid should be assigned to the one that we 
are allocating. I think this is getting over-written when 
iommu_psdtable_prepare() calls into arm_smmu_prepare_cd() where the 
correct asid value is assigned. I will remove this.

> 
>> +
>> +	pst_cfg->fmt = PASID_TABLE_ARM_SMMU_V3;
> 
> Parent function can set this

Sure.

> 
>> +	/* 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.

Regarding this Eric pointed out [1] in my other patch about the 
scalability of the approach where we keep adding flags in 
'iommu_nesting_info' corresponding to the arm-smmu-v3 capabilities. I 
guess the same goes to these flags in virtio.
May be the 'iommu_nesting_info' can have a bitmap with the caps for 
vendor specific features, and here we can add the related flags?

> 
>> +
>> +	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())

Right.

> 
>> +		pst_cfg->fmt = PASID_TABLE_ARM_SMMU_V3;
> 
> Already set above

Right.

> 
>> +
>> +		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.

Yea, will move it to the next patch.

Thanks & regards
Vivek

> 
> 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
>>

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