[PATCH 03/37] iommu/sva: Manage process address spaces

[Jean-Philippe Brucker]

On 24/04/18 02:32, Sinan Kaya wrote:
> On 2/12/2018 1:33 PM, Jean-Philippe Brucker wrote:
>> /**
>>   * iommu_sva_device_init() - Initialize Shared Virtual Addressing for a device
>>   * @dev: the device
>> @@ -129,7 +439,10 @@ EXPORT_SYMBOL_GPL(iommu_sva_device_shutdown);
>>  int iommu_sva_bind_device(struct device *dev, struct mm_struct *mm, int *pasid,
>>  			  unsigned long flags, void *drvdata)
>>  {
>> +	int i, ret;
>> +	struct io_mm *io_mm = NULL;
>>  	struct iommu_domain *domain;
>> +	struct iommu_bond *bond = NULL, *tmp;
>>  	struct iommu_param *dev_param = dev->iommu_param;
>>  
>>  	domain = iommu_get_domain_for_dev(dev);
>> @@ -145,7 +458,42 @@ int iommu_sva_bind_device(struct device *dev, struct mm_struct *mm, int *pasid,
>>  	if (flags != (IOMMU_SVA_FEAT_PASID | IOMMU_SVA_FEAT_IOPF))
>>  		return -EINVAL;
>>  
>> -	return -ENOSYS; /* TODO */
>> +	/* If an io_mm already exists, use it */
>> +	spin_lock(&iommu_sva_lock);
>> +	idr_for_each_entry(&iommu_pasid_idr, io_mm, i) {
>> +		if (io_mm->mm != mm || !io_mm_get_locked(io_mm))
>> +			continue;
>> +
>> +		/* Is it already bound to this device? */
>> +		list_for_each_entry(tmp, &io_mm->devices, mm_head) {
>> +			if (tmp->dev != dev)
>> +				continue;
>> +
>> +			bond = tmp;
>> +			refcount_inc(&bond->refs);
>> +			io_mm_put_locked(io_mm);
>> +			break;
>> +		}
>> +		break;
>> +	}
>> +	spin_unlock(&iommu_sva_lock);
>> +
>> +	if (bond)
> 
> Please return pasid when you find an io_mm that is already bound. Something like
> *pasid = io_mm->pasid should do the work here when bond is true.

Right. I think we should also keep returning 0, not switch to -EEXIST or
similar. So in next version a driver can call bind(devX, mmY) multiple
times, but the first unbind() removes the bond.

Thanks,
Jean