Re: [PATCH 3/9] vfio/mdev: Pass in a struct vfio_device * to vfio_pin/unpin_pages()

[Eric Farman <farman@linux.ibm.com>]

On Tue, 2022-04-12 at 12:53 -0300, Jason Gunthorpe wrote:
> Every caller has a readily available vfio_device pointer, use that
> instead
> of passing in a generic struct device. The struct vfio_device already
> contains the group we need so this avoids complexity, extra
> refcountings,
> and a confusing lifecycle model.
> 
> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
> ---
>  .../driver-api/vfio-mediated-device.rst       |  4 +-
>  drivers/s390/cio/vfio_ccw_cp.c                |  6 +--
>  drivers/s390/crypto/vfio_ap_ops.c             |  8 ++--
>  drivers/vfio/vfio.c                           | 40 ++++++-----------
> --
>  include/linux/vfio.h                          |  4 +-
>  5 files changed, 24 insertions(+), 38 deletions(-)

For the -ccw bits:

Acked-by: Eric Farman <farman@linux.ibm.com>

> 
> diff --git a/Documentation/driver-api/vfio-mediated-device.rst
> b/Documentation/driver-api/vfio-mediated-device.rst
> index 9f26079cacae35..6aeca741dc9be1 100644
> --- a/Documentation/driver-api/vfio-mediated-device.rst
> +++ b/Documentation/driver-api/vfio-mediated-device.rst
> @@ -279,10 +279,10 @@ Translation APIs for Mediated Devices
>  The following APIs are provided for translating user pfn to host pfn
> in a VFIO
>  driver::
>  
> -	extern int vfio_pin_pages(struct device *dev, unsigned long
> *user_pfn,
> +	extern int vfio_pin_pages(struct vfio_device *vdev, unsigned
> long *user_pfn,
>  				  int npage, int prot, unsigned long
> *phys_pfn);
>  
> -	extern int vfio_unpin_pages(struct device *dev, unsigned long
> *user_pfn,
> +	extern int vfio_unpin_pages(struct vfio_device *vdev, unsigned
> long *user_pfn,
>  				    int npage);
>  
>  These functions call back into the back-end IOMMU module by using
> the pin_pages
> diff --git a/drivers/s390/cio/vfio_ccw_cp.c
> b/drivers/s390/cio/vfio_ccw_cp.c
> index af5048a1ba8894..e362cb962a7234 100644
> --- a/drivers/s390/cio/vfio_ccw_cp.c
> +++ b/drivers/s390/cio/vfio_ccw_cp.c
> @@ -103,13 +103,13 @@ static int pfn_array_pin(struct pfn_array *pa,
> struct vfio_device *vdev)
>  {
>  	int ret = 0;
>  
> -	ret = vfio_pin_pages(vdev->dev, pa->pa_iova_pfn, pa->pa_nr,
> +	ret = vfio_pin_pages(vdev, pa->pa_iova_pfn, pa->pa_nr,
>  			     IOMMU_READ | IOMMU_WRITE, pa->pa_pfn);
>  
>  	if (ret < 0) {
>  		goto err_out;
>  	} else if (ret > 0 && ret != pa->pa_nr) {
> -		vfio_unpin_pages(vdev->dev, pa->pa_iova_pfn, ret);
> +		vfio_unpin_pages(vdev, pa->pa_iova_pfn, ret);
>  		ret = -EINVAL;
>  		goto err_out;
>  	}
> @@ -127,7 +127,7 @@ static void pfn_array_unpin_free(struct pfn_array
> *pa, struct vfio_device *vdev)
>  {
>  	/* Only unpin if any pages were pinned to begin with */
>  	if (pa->pa_nr)
> -		vfio_unpin_pages(vdev->dev, pa->pa_iova_pfn, pa-
> >pa_nr);
> +		vfio_unpin_pages(vdev, pa->pa_iova_pfn, pa->pa_nr);
>  	pa->pa_nr = 0;
>  	kfree(pa->pa_iova_pfn);
>  }
> diff --git a/drivers/s390/crypto/vfio_ap_ops.c
> b/drivers/s390/crypto/vfio_ap_ops.c
> index 69768061cd7bd9..a10b3369d76c41 100644
> --- a/drivers/s390/crypto/vfio_ap_ops.c
> +++ b/drivers/s390/crypto/vfio_ap_ops.c
> @@ -124,7 +124,7 @@ static void vfio_ap_free_aqic_resources(struct
> vfio_ap_queue *q)
>  		q->saved_isc = VFIO_AP_ISC_INVALID;
>  	}
>  	if (q->saved_pfn && !WARN_ON(!q->matrix_mdev)) {
> -		vfio_unpin_pages(mdev_dev(q->matrix_mdev->mdev),
> +		vfio_unpin_pages(&q->matrix_mdev->vdev,
>  				 &q->saved_pfn, 1);
>  		q->saved_pfn = 0;
>  	}
> @@ -258,7 +258,7 @@ static struct ap_queue_status
> vfio_ap_irq_enable(struct vfio_ap_queue *q,
>  		return status;
>  	}
>  
> -	ret = vfio_pin_pages(mdev_dev(q->matrix_mdev->mdev), &g_pfn, 1,
> +	ret = vfio_pin_pages(&q->matrix_mdev->vdev, &g_pfn, 1,
>  			     IOMMU_READ | IOMMU_WRITE, &h_pfn);
>  	switch (ret) {
>  	case 1:
> @@ -301,7 +301,7 @@ static struct ap_queue_status
> vfio_ap_irq_enable(struct vfio_ap_queue *q,
>  		break;
>  	case AP_RESPONSE_OTHERWISE_CHANGED:
>  		/* We could not modify IRQ setings: clear new
> configuration */
> -		vfio_unpin_pages(mdev_dev(q->matrix_mdev->mdev),
> &g_pfn, 1);
> +		vfio_unpin_pages(&q->matrix_mdev->vdev, &g_pfn, 1);
>  		kvm_s390_gisc_unregister(kvm, isc);
>  		break;
>  	default:
> @@ -1250,7 +1250,7 @@ static int vfio_ap_mdev_iommu_notifier(struct
> notifier_block *nb,
>  		struct vfio_iommu_type1_dma_unmap *unmap = data;
>  		unsigned long g_pfn = unmap->iova >> PAGE_SHIFT;
>  
> -		vfio_unpin_pages(mdev_dev(matrix_mdev->mdev), &g_pfn,
> 1);
> +		vfio_unpin_pages(&matrix_mdev->vdev, &g_pfn, 1);
>  		return NOTIFY_OK;
>  	}
>  
> diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
> index 8a5c46aa2bef61..24b92a45cfc8f1 100644
> --- a/drivers/vfio/vfio.c
> +++ b/drivers/vfio/vfio.c
> @@ -2142,32 +2142,26 @@
> EXPORT_SYMBOL(vfio_set_irqs_validate_and_prepare);
>   * @phys_pfn[out]: array of host PFNs
>   * Return error or number of pages pinned.
>   */
> -int vfio_pin_pages(struct device *dev, unsigned long *user_pfn, int
> npage,
> +int vfio_pin_pages(struct vfio_device *vdev, unsigned long
> *user_pfn, int npage,
>  		   int prot, unsigned long *phys_pfn)
>  {
>  	struct vfio_container *container;
> -	struct vfio_group *group;
> +	struct vfio_group *group = vdev->group;
>  	struct vfio_iommu_driver *driver;
>  	int ret;
>  
> -	if (!dev || !user_pfn || !phys_pfn || !npage)
> +	if (!user_pfn || !phys_pfn || !npage)
>  		return -EINVAL;
>  
>  	if (npage > VFIO_PIN_PAGES_MAX_ENTRIES)
>  		return -E2BIG;
>  
> -	group = vfio_group_get_from_dev(dev);
> -	if (!group)
> -		return -ENODEV;
> -
> -	if (group->dev_counter > 1) {
> -		ret = -EINVAL;
> -		goto err_pin_pages;
> -	}
> +	if (group->dev_counter > 1)
> +		return -EINVAL;
>  
>  	ret = vfio_group_add_container_user(group);
>  	if (ret)
> -		goto err_pin_pages;
> +		return ret;
>  
>  	container = group->container;
>  	driver = container->iommu_driver;
> @@ -2180,8 +2174,6 @@ int vfio_pin_pages(struct device *dev, unsigned
> long *user_pfn, int npage,
>  
>  	vfio_group_try_dissolve_container(group);
>  
> -err_pin_pages:
> -	vfio_group_put(group);
>  	return ret;
>  }
>  EXPORT_SYMBOL(vfio_pin_pages);
> @@ -2195,28 +2187,24 @@ EXPORT_SYMBOL(vfio_pin_pages);
>   *                 be greater than VFIO_PIN_PAGES_MAX_ENTRIES.
>   * Return error or number of pages unpinned.
>   */
> -int vfio_unpin_pages(struct device *dev, unsigned long *user_pfn,
> int npage)
> +int vfio_unpin_pages(struct vfio_device *vdev, unsigned long
> *user_pfn,
> +		     int npage)
>  {
>  	struct vfio_container *container;
> -	struct vfio_group *group;
>  	struct vfio_iommu_driver *driver;
>  	int ret;
>  
> -	if (!dev || !user_pfn || !npage)
> +	if (!user_pfn || !npage)
>  		return -EINVAL;
>  
>  	if (npage > VFIO_PIN_PAGES_MAX_ENTRIES)
>  		return -E2BIG;
>  
> -	group = vfio_group_get_from_dev(dev);
> -	if (!group)
> -		return -ENODEV;
> -
> -	ret = vfio_group_add_container_user(group);
> +	ret = vfio_group_add_container_user(vdev->group);
>  	if (ret)
> -		goto err_unpin_pages;
> +		return ret;
>  
> -	container = group->container;
> +	container = vdev->group->container;
>  	driver = container->iommu_driver;
>  	if (likely(driver && driver->ops->unpin_pages))
>  		ret = driver->ops->unpin_pages(container->iommu_data,
> user_pfn,
> @@ -2224,10 +2212,8 @@ int vfio_unpin_pages(struct device *dev,
> unsigned long *user_pfn, int npage)
>  	else
>  		ret = -ENOTTY;
>  
> -	vfio_group_try_dissolve_container(group);
> +	vfio_group_try_dissolve_container(vdev->group);
>  
> -err_unpin_pages:
> -	vfio_group_put(group);
>  	return ret;
>  }
>  EXPORT_SYMBOL(vfio_unpin_pages);
> diff --git a/include/linux/vfio.h b/include/linux/vfio.h
> index 748ec0e0293aea..8f2a09801a660b 100644
> --- a/include/linux/vfio.h
> +++ b/include/linux/vfio.h
> @@ -150,9 +150,9 @@ extern long vfio_external_check_extension(struct
> vfio_group *group,
>  
>  #define VFIO_PIN_PAGES_MAX_ENTRIES	(PAGE_SIZE/sizeof(unsigned
> long))
>  
> -extern int vfio_pin_pages(struct device *dev, unsigned long
> *user_pfn,
> +extern int vfio_pin_pages(struct vfio_device *vdev, unsigned long
> *user_pfn,
>  			  int npage, int prot, unsigned long
> *phys_pfn);
> -extern int vfio_unpin_pages(struct device *dev, unsigned long
> *user_pfn,
> +extern int vfio_unpin_pages(struct vfio_device *vdev, unsigned long
> *user_pfn,
>  			    int npage);
>  
>  extern int vfio_group_pin_pages(struct vfio_group *group,