Re: [RFC PATCH 1/8] iommu: Introduce bind_pasid_table API function

[Alex Williamson <alex.williamson-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

On Wed, 26 Apr 2017 18:11:58 +0800
"Liu, Yi L" <yi.l.liu-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org> wrote:

> From: Jacob Pan <jacob.jun.pan-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
> 
> Virtual IOMMU was proposed to support Shared Virtual Memory (SVM) use
> case in the guest:
> https://lists.gnu.org/archive/html/qemu-devel/2016-11/msg05311.html
> 
> As part of the proposed architecture, when a SVM capable PCI
> device is assigned to a guest, nested mode is turned on. Guest owns the
> first level page tables (request with PASID) and performs GVA->GPA
> translation. Second level page tables are owned by the host for GPA->HPA
> translation for both request with and without PASID.
> 
> A new IOMMU driver interface is therefore needed to perform tasks as
> follows:
> * Enable nested translation and appropriate translation type
> * Assign guest PASID table pointer (in GPA) and size to host IOMMU
> 
> This patch introduces new functions called iommu_(un)bind_pasid_table()
> to IOMMU APIs. Architecture specific IOMMU function can be added later
> to perform the specific steps for binding pasid table of assigned devices.
> 
> This patch also adds model definition in iommu.h. It would be used to
> check if the bind request is from a compatible entity. e.g. a bind
> request from an intel_iommu emulator may not be supported by an ARM SMMU
> driver.
> 
> Signed-off-by: Jacob Pan <jacob.jun.pan-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
> Signed-off-by: Liu, Yi L <yi.l.liu-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
> ---
>  drivers/iommu/iommu.c | 19 +++++++++++++++++++
>  include/linux/iommu.h | 31 +++++++++++++++++++++++++++++++
>  2 files changed, 50 insertions(+)
> 
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index dbe7f65..f2da636 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -1134,6 +1134,25 @@ int iommu_attach_device(struct iommu_domain *domain, struct device *dev)
>  }
>  EXPORT_SYMBOL_GPL(iommu_attach_device);
>  
> +int iommu_bind_pasid_table(struct iommu_domain *domain, struct device *dev,
> +			struct pasid_table_info *pasidt_binfo)
> +{
> +	if (unlikely(!domain->ops->bind_pasid_table))
> +		return -EINVAL;
> +
> +	return domain->ops->bind_pasid_table(domain, dev, pasidt_binfo);
> +}
> +EXPORT_SYMBOL_GPL(iommu_bind_pasid_table);
> +
> +int iommu_unbind_pasid_table(struct iommu_domain *domain, struct device *dev)
> +{
> +	if (unlikely(!domain->ops->unbind_pasid_table))
> +		return -EINVAL;
> +
> +	return domain->ops->unbind_pasid_table(domain, dev);
> +}
> +EXPORT_SYMBOL_GPL(iommu_unbind_pasid_table);
> +
>  static void __iommu_detach_device(struct iommu_domain *domain,
>  				  struct device *dev)
>  {
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 0ff5111..491a011 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -131,6 +131,15 @@ struct iommu_dm_region {
>  	int			prot;
>  };
>  
> +struct pasid_table_info {
> +	__u64	ptr;	/* PASID table ptr */
> +	__u64	size;	/* PASID table size*/
> +	__u32	model;	/* magic number */
> +#define INTEL_IOMMU	(1 << 0)
> +#define ARM_SMMU	(1 << 1)
> +	__u8	opaque[];/* IOMMU-specific details */
> +};

This needs to be in uapi since you're expecting a user to pass it 

> +
>  #ifdef CONFIG_IOMMU_API
>  
>  /**
> @@ -159,6 +168,8 @@ struct iommu_dm_region {
>   * @domain_get_windows: Return the number of windows for a domain
>   * @of_xlate: add OF master IDs to iommu grouping
>   * @pgsize_bitmap: bitmap of all possible supported page sizes
> + * @bind_pasid_table: bind pasid table pointer for guest SVM
> + * @unbind_pasid_table: unbind pasid table pointer and restore defaults
>   */
>  struct iommu_ops {
>  	bool (*capable)(enum iommu_cap);
> @@ -200,6 +211,10 @@ struct iommu_ops {
>  	u32 (*domain_get_windows)(struct iommu_domain *domain);
>  
>  	int (*of_xlate)(struct device *dev, struct of_phandle_args *args);
> +	int (*bind_pasid_table)(struct iommu_domain *domain, struct device *dev,
> +				struct pasid_table_info *pasidt_binfo);
> +	int (*unbind_pasid_table)(struct iommu_domain *domain,
> +				struct device *dev);
>  
>  	unsigned long pgsize_bitmap;
>  };
> @@ -221,6 +236,10 @@ extern int iommu_attach_device(struct iommu_domain *domain,
>  			       struct device *dev);
>  extern void iommu_detach_device(struct iommu_domain *domain,
>  				struct device *dev);
> +extern int iommu_bind_pasid_table(struct iommu_domain *domain,
> +		struct device *dev, struct pasid_table_info *pasidt_binfo);
> +extern int iommu_unbind_pasid_table(struct iommu_domain *domain,
> +				struct device *dev);
>  extern struct iommu_domain *iommu_get_domain_for_dev(struct device *dev);
>  extern int iommu_map(struct iommu_domain *domain, unsigned long iova,
>  		     phys_addr_t paddr, size_t size, int prot);
> @@ -595,6 +614,18 @@ const struct iommu_ops *iommu_get_instance(struct fwnode_handle *fwnode)
>  	return NULL;
>  }
>  
> +static inline
> +int iommu_bind_pasid_table(struct iommu_domain *domain, struct device *dev,
> +			struct pasid_table_info *pasidt_binfo)
> +{
> +	return -EINVAL;
> +}
> +static inline
> +int iommu_unbind_pasid_table(struct iommu_domain *domain, struct device *dev)
> +{
> +	return -EINVAL;
> +}
> +
>  #endif /* CONFIG_IOMMU_API */
>  
>  #endif /* __LINUX_IOMMU_H */