linux-kernel - Re: [PATCH v10 05/19] vfio iommu: Added pin and unpin callback functions to vfio_iommu_driver

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Message-ID: <58184D54.7020301@intel.com>
Date:   Tue, 01 Nov 2016 16:07:48 +0800
From:   Jike Song <jike.song@...el.com>
To:     Kirti Wankhede <kwankhede@...dia.com>
CC:     alex.williamson@...hat.com, pbonzini@...hat.com, kraxel@...hat.com,
        cjia@...dia.com, qemu-devel@...gnu.org, kvm@...r.kernel.org,
        kevin.tian@...el.com, bjsdjshi@...ux.vnet.ibm.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v10 05/19] vfio iommu: Added pin and unpin callback functions
 to vfio_iommu_driver_ops

On 10/27/2016 05:29 AM, Kirti Wankhede wrote:
> Added two new callback functions to struct vfio_iommu_driver_ops. Backend
> IOMMU module that supports pining and unpinning pages for mdev devices
> should provide these functions.
> Added APIs for pining and unpining pages to VFIO module. These calls back
> into backend iommu module to actually pin and unpin pages.
> 
> Signed-off-by: Kirti Wankhede <kwankhede@...dia.com>
> Signed-off-by: Neo Jia <cjia@...dia.com>
> Change-Id: Ia7417723aaae86bec2959ad9ae6c2915ddd340e0
> ---
>  drivers/vfio/vfio.c  | 92 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/vfio.h | 12 ++++++-
>  2 files changed, 103 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
> index 2e83bdf007fe..28b50ca14c52 100644
> --- a/drivers/vfio/vfio.c
> +++ b/drivers/vfio/vfio.c
> @@ -1799,6 +1799,98 @@ void vfio_info_cap_shift(struct vfio_info_cap *caps, size_t offset)
>  }
>  EXPORT_SYMBOL_GPL(vfio_info_cap_shift);
>  
> +
> +/*
> + * Pin a set of guest PFNs and return their associated host PFNs for local
> + * domain only.
> + * @dev [in] : device
> + * @user_pfn [in]: array of user/guest PFNs
> + * @npage [in]: count of array elements
> + * @prot [in] : protection flags
> + * @phys_pfn[out] : array of host PFNs
> + */

Hi Kirti,

Would you also add the documentation what the return value is? It's kind
not clear, and any reason to use long instead of int?

> +long vfio_pin_pages(struct device *dev, unsigned long *user_pfn,
> +		    long npage, int prot, unsigned long *phys_pfn)
> +{
> +	struct vfio_container *container;
> +	struct vfio_group *group;
> +	struct vfio_iommu_driver *driver;
> +	ssize_t ret;
> +
> +	if (!dev || !user_pfn || !phys_pfn)
> +		return -EINVAL;
> +
> +	group = vfio_group_get_from_dev(dev);
> +	if (IS_ERR(group))
> +		return PTR_ERR(group);
> +
> +	ret = vfio_group_add_container_user(group);
> +	if (ret)
> +		goto err_pin_pages;
> +
> +	container = group->container;
> +	down_read(&container->group_lock);
> +
> +	driver = container->iommu_driver;
> +	if (likely(driver && driver->ops->pin_pages))
> +		ret = driver->ops->pin_pages(container->iommu_data, user_pfn,
> +					     npage, prot, phys_pfn);
> +	else
> +		ret = -EINVAL;
> +
> +	up_read(&container->group_lock);
> +	vfio_group_try_dissolve_container(group);
> +
> +err_pin_pages:
> +	vfio_group_put(group);
> +	return ret;
> +
> +}
> +EXPORT_SYMBOL(vfio_pin_pages);
> +
> +/*
> + * Unpin set of host PFNs for local domain only.
> + * @dev [in] : device
> + * @pfn [in] : array of host PFNs to be unpinned.
> + * @npage [in] :count of elements in array, that is number of pages.
> + */

Ditto

--
Thanks,
Jike

> +long vfio_unpin_pages(struct device *dev, unsigned long *pfn, long npage)
> +{
> +	struct vfio_container *container;
> +	struct vfio_group *group;
> +	struct vfio_iommu_driver *driver;
> +	ssize_t ret;
> +
> +	if (!dev || !pfn)
> +		return -EINVAL;
> +
> +	group = vfio_group_get_from_dev(dev);
> +	if (IS_ERR(group))
> +		return PTR_ERR(group);
> +
> +	ret = vfio_group_add_container_user(group);
> +	if (ret)
> +		goto err_unpin_pages;
> +
> +	container = group->container;
> +	down_read(&container->group_lock);
> +
> +	driver = container->iommu_driver;
> +	if (likely(driver && driver->ops->unpin_pages))
> +		ret = driver->ops->unpin_pages(container->iommu_data, pfn,
> +					       npage);
> +	else
> +		ret = -EINVAL;
> +
> +	up_read(&container->group_lock);
> +	vfio_group_try_dissolve_container(group);
> +
> +err_unpin_pages:
> +	vfio_group_put(group);
> +	return ret;
> +}
> +EXPORT_SYMBOL(vfio_unpin_pages);
> +
>  /**
>   * Module/class support
>   */
> diff --git a/include/linux/vfio.h b/include/linux/vfio.h
> index 0ecae0b1cd34..0609a2052846 100644
> --- a/include/linux/vfio.h
> +++ b/include/linux/vfio.h
> @@ -75,7 +75,11 @@ struct vfio_iommu_driver_ops {
>  					struct iommu_group *group);
>  	void		(*detach_group)(void *iommu_data,
>  					struct iommu_group *group);
> -
> +	long		(*pin_pages)(void *iommu_data, unsigned long *user_pfn,
> +				     long npage, int prot,
> +				     unsigned long *phys_pfn);
> +	long		(*unpin_pages)(void *iommu_data, unsigned long *pfn,
> +				       long npage);
>  };
>  
>  extern int vfio_register_iommu_driver(const struct vfio_iommu_driver_ops *ops);
> @@ -127,6 +131,12 @@ static inline long vfio_spapr_iommu_eeh_ioctl(struct iommu_group *group,
>  }
>  #endif /* CONFIG_EEH */
>  
> +extern long vfio_pin_pages(struct device *dev, unsigned long *user_pfn,
> +			   long npage, int prot, unsigned long *phys_pfn);
> +
> +extern long vfio_unpin_pages(struct device *dev, unsigned long *pfn,
> +			     long npage);
> +
>  /*
>   * IRQfd - generic
>   */
>