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

[Yisheng Xie <xieyisheng1@huawei.com>]

Hi Jean,

On 2018/2/22 14:23, Jean-Philippe Brucker wrote:
> @@ -129,7 +439,10 @@ int iommu_sva_device_shutdown(struct device *dev)
>  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);

Should io_mm->pasid still be set to *pasid when the device already bond? so driver can
always get the right pasid if it bond to a mm multi-times, without keeping the pasid itself?

Thanks
Yisheng
> +			break;
> +		}
> +		break;
> +	}
> +	spin_unlock(&iommu_sva_lock);
> +
> +	if (bond)
> +		return 0;
> +
> +	if (!io_mm) {
> +		io_mm = io_mm_alloc(domain, dev, mm);
> +		if (IS_ERR(io_mm))
> +			return PTR_ERR(io_mm);
> +	}
> +
> +	ret = io_mm_attach(domain, dev, io_mm, drvdata);
> +	if (ret)
> +		io_mm_put(io_mm);
> +	else
> +		*pasid = io_mm->pasid;
> +
> +	return ret;
>  }
>  EXPORT_SYMBOL_GPL(iommu_sva_bind_device);