linux-kernel - Re: [PATCH 05/20] iommu: Add iommu_paging_domain

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Date: Wed, 29 May 2024 17:04:28 +0800
From: Yi Liu <yi.l.liu@...el.com>
To: Lu Baolu <baolu.lu@...ux.intel.com>, Joerg Roedel <joro@...tes.org>, "Will
 Deacon" <will@...nel.org>, Robin Murphy <robin.murphy@....com>, "Jason
 Gunthorpe" <jgg@...pe.ca>, Kevin Tian <kevin.tian@...el.com>
CC: David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>, "Kalle
 Valo" <kvalo@...nel.org>, Bjorn Andersson <andersson@...nel.org>, "Mathieu
 Poirier" <mathieu.poirier@...aro.org>, Alex Williamson
	<alex.williamson@...hat.com>, <mst@...hat.com>, Jason Wang
	<jasowang@...hat.com>, Thierry Reding <thierry.reding@...il.com>, "Jonathan
 Hunter" <jonathanh@...dia.com>, Mikko Perttunen <mperttunen@...dia.com>,
	<iommu@...ts.linux.dev>, <dri-devel@...ts.freedesktop.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 05/20] iommu: Add iommu_paging_domain_alloc() interface

On 2024/5/29 13:32, Lu Baolu wrote:
> Commit <17de3f5fdd35> ("iommu: Retire bus ops") removes iommu ops from
> bus. The iommu subsystem no longer relies on bus for operations. So the
> bus parameter in iommu_domain_alloc() is no longer relevant.
> 
> Add a new interface named iommu_paging_domain_alloc(), which explicitly
> indicates the allocation of a paging domain for DMA managed by a kernel
> driver. The new interface takes a device pointer as its parameter, that
> better aligns with the current iommu subsystem.

you may want to move this patch before patch 03/04.

> Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
> ---
>   include/linux/iommu.h |  6 ++++++
>   drivers/iommu/iommu.c | 20 ++++++++++++++++++++
>   2 files changed, 26 insertions(+)
> 
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 6648b2415474..16401de7802d 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -781,6 +781,7 @@ extern bool device_iommu_capable(struct device *dev, enum iommu_cap cap);
>   extern bool iommu_group_has_isolated_msi(struct iommu_group *group);
>   extern struct iommu_domain *iommu_domain_alloc(const struct bus_type *bus);
>   struct iommu_domain *iommu_user_domain_alloc(struct device *dev, u32 flags);
> +struct iommu_domain *iommu_paging_domain_alloc(struct device *dev);
>   extern void iommu_domain_free(struct iommu_domain *domain);
>   extern int iommu_attach_device(struct iommu_domain *domain,
>   			       struct device *dev);
> @@ -1092,6 +1093,11 @@ static inline struct iommu_domain *iommu_user_domain_alloc(struct device *dev, u
>   	return ERR_PTR(-ENODEV);
>   }
>   
> +static inline struct iommu_domain *iommu_paging_domain_alloc(struct device *dev)
> +{
> +	return ERR_PTR(-ENODEV);
> +}
> +
>   static inline void iommu_domain_free(struct iommu_domain *domain)
>   {
>   }
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index f1416892ef8e..7df4a021b040 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -2016,6 +2016,10 @@ static int __iommu_domain_alloc_dev(struct device *dev, void *data)
>   	return 0;
>   }
>   
> +/*
> + * The iommu ops in bus has been retired. Do not use this interface in
> + * new drivers.
> + */
>   struct iommu_domain *iommu_domain_alloc(const struct bus_type *bus)
>   {
>   	const struct iommu_ops *ops = NULL;
> @@ -2074,6 +2078,22 @@ struct iommu_domain *iommu_user_domain_alloc(struct device *dev, u32 flags)
>   }
>   EXPORT_SYMBOL_GPL(iommu_user_domain_alloc);
>   
> +/**
> + * iommu_paging_domain_alloc() - Allocate a paging domain
> + * @dev: device for which the domain is allocated
> + *
> + * Allocate a paging domain which will be managed by a kernel driver. Return
> + * allocated domain if successful, or a ERR pointer for failure.
> + */
> +struct iommu_domain *iommu_paging_domain_alloc(struct device *dev)
> +{
> +	if (!dev_has_iommu(dev))
> +		return ERR_PTR(-ENODEV);
> +
> +	return __iommu_domain_alloc(dev_iommu_ops(dev), dev, IOMMU_DOMAIN_UNMANAGED);
> +}
> +EXPORT_SYMBOL_GPL(iommu_paging_domain_alloc);
> +
>   void iommu_domain_free(struct iommu_domain *domain)
>   {
>   	if (domain->type == IOMMU_DOMAIN_SVA)

-- 
Regards,
Yi Liu