linux-kernel - Re: [RFC v3 04/10] iommu: iommu_alloc_resv

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Date:   Tue, 6 Dec 2016 17:30:44 +0000
From:   Robin Murphy <robin.murphy@....com>
To:     Eric Auger <eric.auger@...hat.com>, eric.auger.pro@...il.com,
        christoffer.dall@...aro.org, marc.zyngier@....com,
        alex.williamson@...hat.com, will.deacon@....com, joro@...tes.org,
        tglx@...utronix.de, jason@...edaemon.net,
        linux-arm-kernel@...ts.infradead.org
Cc:     kvm@...r.kernel.org, drjones@...hat.com,
        linux-kernel@...r.kernel.org, pranav.sawargaonkar@...il.com,
        iommu@...ts.linux-foundation.org, punit.agrawal@....com,
        diana.craciun@....com
Subject: Re: [RFC v3 04/10] iommu: iommu_alloc_resv_region

On 15/11/16 13:09, Eric Auger wrote:
> Introduce a new helper serving the purpose to allocate a reserved
> region.  This will be used in iommu driver implementing reserved
> region callbacks.
> 
> Signed-off-by: Eric Auger <eric.auger@...hat.com>
> ---
>  drivers/iommu/iommu.c | 16 ++++++++++++++++
>  include/linux/iommu.h |  8 ++++++++
>  2 files changed, 24 insertions(+)
> 
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index c7ed334..6ee529f 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -1562,6 +1562,22 @@ void iommu_put_resv_regions(struct device *dev, struct list_head *list)
>  		ops->put_resv_regions(dev, list);
>  }
>  
> +struct iommu_resv_region *iommu_alloc_resv_region(phys_addr_t start,
> +						  size_t length,
> +						  unsigned int prot)
> +{
> +	struct iommu_resv_region *region;
> +
> +	region = kzalloc(sizeof(*region), GFP_KERNEL);
> +	if (!region)
> +		return NULL;
> +
> +	region->start = start;
> +	region->length = length;
> +	region->prot = prot;
> +	return region;
> +}

I think you need an INIT_LIST_HEAD() in here as well, or
CONFIG_DEBUG_LIST might get unhappy about using an uninitialised head later.

Robin.

> +
>  /* Request that a device is direct mapped by the IOMMU */
>  int iommu_request_dm_for_dev(struct device *dev)
>  {
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 02cf565..0aea877 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -241,6 +241,8 @@ extern void iommu_set_fault_handler(struct iommu_domain *domain,
>  extern void iommu_get_resv_regions(struct device *dev, struct list_head *list);
>  extern void iommu_put_resv_regions(struct device *dev, struct list_head *list);
>  extern int iommu_request_dm_for_dev(struct device *dev);
> +extern struct iommu_resv_region *
> +iommu_alloc_resv_region(phys_addr_t start, size_t length, unsigned int prot);
>  
>  extern int iommu_attach_group(struct iommu_domain *domain,
>  			      struct iommu_group *group);
> @@ -454,6 +456,12 @@ static inline void iommu_put_resv_regions(struct device *dev,
>  {
>  }
>  
> +static inline struct iommu_resv_region *
> +iommu_alloc_resv_region(phys_addr_t start, size_t length, unsigned int prot)
> +{
> +	return NULL;
> +}
> +
>  static inline int iommu_request_dm_for_dev(struct device *dev)
>  {
>  	return -ENODEV;
>