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

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Date:   Tue, 28 Jun 2022 13:53:35 +0800
From:   Baolu Lu <baolu.lu@...ux.intel.com>
To:     "Tian, Kevin" <kevin.tian@...el.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:     baolu.lu@...ux.intel.com, 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()

On 2022/6/27 18:14, Tian, Kevin wrote:
>> 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()

Updated.

> 
>> +	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.

It's part of current IOMMU/SVA interfaces for the device drivers, and
has been used in various drivers.

$ git grep iommu_sva_get_pasid
drivers/dma/idxd/cdev.c:                pasid = iommu_sva_get_pasid(sva);
drivers/iommu/iommu-sva-lib.c:  ioasid_t pasid = 
iommu_sva_get_pasid(handle);
drivers/iommu/iommu-sva-lib.c:u32 iommu_sva_get_pasid(struct iommu_sva 
*handle)
drivers/iommu/iommu-sva-lib.c:EXPORT_SYMBOL_GPL(iommu_sva_get_pasid);
drivers/misc/uacce/uacce.c:     pasid = iommu_sva_get_pasid(handle);
include/linux/iommu.h:u32 iommu_sva_get_pasid(struct iommu_sva *handle);
include/linux/iommu.h:static inline u32 iommu_sva_get_pasid(struct 
iommu_sva *handle)

Or, I missed anything?

Best regards,
baolu