linux-kernel - Re: [PATCH v6 3/4] iommu/vt-d: Add set_dev

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Message-ID: <ZHUBoBev2Vzp8nGF@nvidia.com>
Date:   Mon, 29 May 2023 16:48:48 -0300
From:   Jason Gunthorpe <jgg@...dia.com>
To:     Jacob Pan <jacob.jun.pan@...ux.intel.com>
Cc:     LKML <linux-kernel@...r.kernel.org>, iommu@...ts.linux.dev,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        Joerg Roedel <joro@...tes.org>, dmaengine@...r.kernel.org,
        vkoul@...nel.org, Robin Murphy <robin.murphy@....com>,
        Will Deacon <will@...nel.org>,
        David Woodhouse <dwmw2@...radead.org>,
        Raj Ashok <ashok.raj@...el.com>,
        "Tian, Kevin" <kevin.tian@...el.com>, Yi Liu <yi.l.liu@...el.com>,
        "Yu, Fenghua" <fenghua.yu@...el.com>,
        Dave Jiang <dave.jiang@...el.com>,
        Tony Luck <tony.luck@...el.com>,
        "Zanussi, Tom" <tom.zanussi@...el.com>,
        narayan.ranganathan@...el.com
Subject: Re: [PATCH v6 3/4] iommu/vt-d: Add set_dev_pasid callback for dma
 domain

On Fri, May 19, 2023 at 01:32:22PM -0700, Jacob Pan wrote:

> @@ -4720,25 +4762,99 @@ static void intel_iommu_iotlb_sync_map(struct iommu_domain *domain,
>  static void intel_iommu_remove_dev_pasid(struct device *dev, ioasid_t pasid)
>  {
>  	struct intel_iommu *iommu = device_to_iommu(dev, NULL, NULL);
> +	struct dev_pasid_info *curr, *dev_pasid = NULL;
> +	struct dmar_domain *dmar_domain;
>  	struct iommu_domain *domain;
> +	unsigned long flags;
>  
> -	/* Domain type specific cleanup: */
>  	domain = iommu_get_domain_for_dev_pasid(dev, pasid, 0);
> -	if (domain) {
> -		switch (domain->type) {
> -		case IOMMU_DOMAIN_SVA:
> -			intel_svm_remove_dev_pasid(dev, pasid);
> -			break;
> -		default:
> -			/* should never reach here */
> -			WARN_ON(1);
> +	if (!domain)
> +		goto out_tear_down;
> +
> +	/*
> +	 * The SVA implementation needs to stop mm notification, drain the
> +	 * pending page fault requests before tearing down the pasid entry.
> +	 * The VT-d spec (section 6.2.3.1) also recommends that software
> +	 * could use a reserved domain id for all first-only and pass-through
> +	 * translations. Hence there's no need to call domain_detach_iommu()
> +	 * in the sva domain case.
> +	 */
> +	if (domain->type == IOMMU_DOMAIN_SVA) {
> +		intel_svm_remove_dev_pasid(dev, pasid);
> +		goto out_tear_down;
> +	}

But why don't you need to do all the other
intel_pasid_tear_down_entry(), intel_svm_drain_prq() (which is
misnamed) and other stuff from intel_svm_remove_dev_pasid() ?

There still seems to be waaay too much "SVM" in the PASID code.

> +static int intel_iommu_set_dev_pasid(struct iommu_domain *domain,
> +				     struct device *dev, ioasid_t pasid)
> +{
> +	struct device_domain_info *info = dev_iommu_priv_get(dev);
> +	struct dmar_domain *dmar_domain = to_dmar_domain(domain);
> +	struct intel_iommu *iommu = info->iommu;
> +	struct dev_pasid_info *dev_pasid;
> +	unsigned long flags;
> +	int ret;
> +
> +	if (!pasid_supported(iommu) || dev_is_real_dma_subdevice(dev))
> +		return -EOPNOTSUPP;
> +
> +	if (context_copied(iommu, info->bus, info->devfn))
> +		return -EBUSY;
> +
> +	ret = prepare_domain_attach_device(domain, dev);
> +	if (ret)
> +		return ret;
> +
> +	dev_pasid = kzalloc(sizeof(*dev_pasid), GFP_KERNEL);
> +	if (!dev_pasid)
> +		return -ENOMEM;
> +
> +	ret = domain_attach_iommu(dmar_domain, iommu);
> +	if (ret)
> +		goto out_free;
> +
> +	if (domain_type_is_si(dmar_domain))
> +		ret = intel_pasid_setup_pass_through(iommu, dmar_domain,
> +						     dev, pasid);
> +	else if (dmar_domain->use_first_level)
> +		ret = domain_setup_first_level(iommu, dmar_domain,
> +					       dev, pasid);
> +	else
> +		ret = intel_pasid_setup_second_level(iommu, dmar_domain,
> +						     dev, pasid);

It would be nice if the different domain types had their own ops..

Jason