linux-kernel - RE: [PATCH v9 07/11] iommu/sva: Refactoring iommu_sva_bind/unbind

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Date:   Mon, 27 Jun 2022 10:14:27 +0000
From:   "Tian, Kevin" <kevin.tian@...el.com>
To:     Lu Baolu <baolu.lu@...ux.intel.com>,
        Joerg Roedel <joro@...tes.org>,
        Jason Gunthorpe <jgg@...dia.com>,
        Christoph Hellwig <hch@...radead.org>,
        "Raj, Ashok" <ashok.raj@...el.com>, Will Deacon <will@...nel.org>,
        "Robin Murphy" <robin.murphy@....com>,
        Jean-Philippe Brucker <jean-philippe@...aro.com>,
        "Jiang, Dave" <dave.jiang@...el.com>, Vinod Koul <vkoul@...nel.org>
CC:     Eric Auger <eric.auger@...hat.com>,
        "Liu, Yi L" <yi.l.liu@...el.com>,
        "Pan, Jacob jun" <jacob.jun.pan@...el.com>,
        "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
        "iommu@...ts.linux.dev" <iommu@...ts.linux.dev>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v9 07/11] iommu/sva: Refactoring
 iommu_sva_bind/unbind_device()

> From: Lu Baolu <baolu.lu@...ux.intel.com>
> Sent: Tuesday, June 21, 2022 10:44 PM
> +struct iommu_sva *iommu_sva_bind_device(struct device *dev, struct
> mm_struct *mm)
> +{
> +	struct iommu_domain *domain;
> +	ioasid_t max_pasids;
> +	int ret = -EINVAL;
> +
> +	/* Allocate mm->pasid if necessary. */

this comment is for iommu_sva_alloc_pasid()

> +	max_pasids = dev->iommu->max_pasids;
> +	if (!max_pasids)
> +		return ERR_PTR(-EOPNOTSUPP);
> +
> +	ret = iommu_sva_alloc_pasid(mm, 1, max_pasids - 1);
> +	if (ret)
> +		return ERR_PTR(ret);
> +


...
> +void iommu_sva_unbind_device(struct iommu_sva *handle)
> +{
> +	struct device *dev = handle->dev;
> +	struct iommu_domain *domain =
> +			container_of(handle, struct iommu_domain, bond);
> +	ioasid_t pasid = iommu_sva_get_pasid(handle);
> +
> +	mutex_lock(&iommu_sva_lock);
> +	if (refcount_dec_and_test(&domain->bond.users)) {
> +		iommu_detach_device_pasid(domain, dev, pasid);
> +		iommu_domain_free(domain);
> +	}
> +	mutex_unlock(&iommu_sva_lock);
> +}
> +EXPORT_SYMBOL_GPL(iommu_sva_unbind_device);
> +
> +u32 iommu_sva_get_pasid(struct iommu_sva *handle)
> +{
> +	struct iommu_domain *domain =
> +			container_of(handle, struct iommu_domain, bond);
> +
> +	return domain->mm->pasid;
> +}
> +EXPORT_SYMBOL_GPL(iommu_sva_get_pasid);

Looks this is only used by unbind_device. Just open code it.