Commit 40280cf7 authored by Yan Zhao's avatar Yan Zhao Committed by Alex Williamson
Browse files

vfio: avoid inefficient operations on VFIO group in vfio_pin/unpin_pages 



vfio_group_pin_pages() and vfio_group_unpin_pages() are introduced to
avoid inefficient search/check/ref/deref opertions associated with VFIO
group as those in each calling into vfio_pin_pages() and
vfio_unpin_pages().

VFIO group is taken as arg directly. The callers combine
search/check/ref/deref operations associated with VFIO group by calling
vfio_group_get_external_user()/vfio_group_get_external_user_from_dev()
beforehand, and vfio_group_put_external_user() afterwards.

Suggested-by: default avatarAlex Williamson <alex.williamson@redhat.com>
Signed-off-by: default avatarYan Zhao <yan.y.zhao@intel.com>
Signed-off-by: default avatarAlex Williamson <alex.williamson@redhat.com>
parent 8d46c0cc

drivers/vfio/vfio.c

+91 −0
Original line number Diff line number Diff line
@@ -1999,6 +1999,97 @@ err_unpin_pages: 
}

EXPORT_SYMBOL(vfio_unpin_pages);



/*

 * Pin a set of guest IOVA PFNs and return their associated host PFNs for a

 * VFIO group.

 *

 * The caller needs to call vfio_group_get_external_user() or

 * vfio_group_get_external_user_from_dev() prior to calling this interface,

 * so as to prevent the VFIO group from disposal in the middle of the call.

 * But it can keep the reference to the VFIO group for several calls into

 * this interface.

 * After finishing using of the VFIO group, the caller needs to release the

 * VFIO group by calling vfio_group_put_external_user().

 *

 * @group [in]		: VFIO group

 * @user_iova_pfn [in]	: array of user/guest IOVA PFNs to be pinned.

 * @npage [in]		: count of elements in user_iova_pfn array.

 *			  This count should not be greater

 *			  VFIO_PIN_PAGES_MAX_ENTRIES.

 * @prot [in]		: protection flags

 * @phys_pfn [out]	: array of host PFNs

 * Return error or number of pages pinned.

 */

int vfio_group_pin_pages(struct vfio_group *group,

			 unsigned long *user_iova_pfn, int npage,

			 int prot, unsigned long *phys_pfn)

{

	struct vfio_container *container;

	struct vfio_iommu_driver *driver;

	int ret;



	if (!group || !user_iova_pfn || !phys_pfn || !npage)

		return -EINVAL;



	if (npage > VFIO_PIN_PAGES_MAX_ENTRIES)

		return -E2BIG;



	container = group->container;

	driver = container->iommu_driver;

	if (likely(driver && driver->ops->pin_pages))

		ret = driver->ops->pin_pages(container->iommu_data,

					     user_iova_pfn, npage,

					     prot, phys_pfn);

	else

		ret = -ENOTTY;



	return ret;

}

EXPORT_SYMBOL(vfio_group_pin_pages);



/*

 * Unpin a set of guest IOVA PFNs for a VFIO group.

 *

 * The caller needs to call vfio_group_get_external_user() or

 * vfio_group_get_external_user_from_dev() prior to calling this interface,

 * so as to prevent the VFIO group from disposal in the middle of the call.

 * But it can keep the reference to the VFIO group for several calls into

 * this interface.

 * After finishing using of the VFIO group, the caller needs to release the

 * VFIO group by calling vfio_group_put_external_user().

 *

 * @group [in]		: vfio group

 * @user_iova_pfn [in]	: array of user/guest IOVA PFNs to be unpinned.

 * @npage [in]		: count of elements in user_iova_pfn array.

 *			  This count should not be greater than

 *			  VFIO_PIN_PAGES_MAX_ENTRIES.

 * Return error or number of pages unpinned.

 */

int vfio_group_unpin_pages(struct vfio_group *group,

			   unsigned long *user_iova_pfn, int npage)

{

	struct vfio_container *container;

	struct vfio_iommu_driver *driver;

	int ret;



	if (!group || !user_iova_pfn || !npage)

		return -EINVAL;



	if (npage > VFIO_PIN_PAGES_MAX_ENTRIES)

		return -E2BIG;



	container = group->container;

	driver = container->iommu_driver;

	if (likely(driver && driver->ops->unpin_pages))

		ret = driver->ops->unpin_pages(container->iommu_data,

					       user_iova_pfn, npage);

	else

		ret = -ENOTTY;



	return ret;

}

EXPORT_SYMBOL(vfio_group_unpin_pages);





/*

 * This interface allows the CPUs to perform some sort of virtual DMA on

include/linux/vfio.h

+6 −0
Original line number Diff line number Diff line
@@ -111,6 +111,12 @@ extern int vfio_pin_pages(struct device *dev, unsigned long *user_pfn, 
extern int vfio_unpin_pages(struct device *dev, unsigned long *user_pfn,

			    int npage);



extern int vfio_group_pin_pages(struct vfio_group *group,

				unsigned long *user_iova_pfn, int npage,

				int prot, unsigned long *phys_pfn);

extern int vfio_group_unpin_pages(struct vfio_group *group,

				  unsigned long *user_iova_pfn, int npage);



extern int vfio_dma_rw(struct vfio_group *group, dma_addr_t user_iova,

		       void *data, size_t len, bool write);

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