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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: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Yan Zhao <yan.y.zhao@intel.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
This commit is contained in:
Yan Zhao 2020-03-24 09:27:57 -06:00 committed by Alex Williamson
parent 8d46c0cca5
commit 40280cf7e8
2 changed files with 97 additions and 0 deletions
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91
drivers/vfio/vfio.c
View File

@ -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

6
include/linux/vfio.h
View File

@ -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);