diff options
| author | Jason Gunthorpe <jgg@nvidia.com> | 2022-11-29 23:29:37 +0300 |
|---|---|---|
| committer | Jason Gunthorpe <jgg@nvidia.com> | 2022-12-01 03:16:49 +0300 |
| commit | 8d40205f6093f18e07fe3dc5920fc85e9f82b8b3 (patch) | |
| tree | d234a41f681336b827ac77cec59b838521832ad9 /drivers/iommu/iommufd/io_pagetable.c | |
| parent | e8d57210035b6377d424ba964961892d01127cf6 (diff) | |
| download | linux-8d40205f6093f18e07fe3dc5920fc85e9f82b8b3.tar.xz | |
iommufd: Add kAPI toward external drivers for kernel access
Kernel access is the mode that VFIO "mdevs" use. In this case there is no
struct device and no IOMMU connection. iommufd acts as a record keeper for
accesses and returns the actual struct pages back to the caller to use
however they need. eg with kmap or the DMA API.
Each caller must create a struct iommufd_access with
iommufd_access_create(), similar to how iommufd_device_bind() works. Using
this struct the caller can access blocks of IOVA using
iommufd_access_pin_pages() or iommufd_access_rw().
Callers must provide a callback that immediately unpins any IOVA being
used within a range. This happens if userspace unmaps the IOVA under the
pin.
The implementation forwards the access requests directly to the iopt
infrastructure that manages the iopt_pages_access.
Link: https://lore.kernel.org/r/14-v6-a196d26f289e+11787-iommufd_jgg@nvidia.com
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Tested-by: Yi Liu <yi.l.liu@intel.com>
Tested-by: Lixiao Yang <lixiao.yang@intel.com>
Tested-by: Matthew Rosato <mjrosato@linux.ibm.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Diffstat (limited to 'drivers/iommu/iommufd/io_pagetable.c')
| -rw-r--r-- | drivers/iommu/iommufd/io_pagetable.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/drivers/iommu/iommufd/io_pagetable.c b/drivers/iommu/iommufd/io_pagetable.c index 756d347948f0..4f4a9d9aac57 100644 --- a/drivers/iommu/iommufd/io_pagetable.c +++ b/drivers/iommu/iommufd/io_pagetable.c @@ -458,6 +458,7 @@ static int iopt_unmap_iova_range(struct io_pagetable *iopt, unsigned long start, * is NULL. This prevents domain attach/detatch from running * concurrently with cleaning up the area. */ +again: down_read(&iopt->domains_rwsem); down_write(&iopt->iova_rwsem); while ((area = iopt_area_iter_first(iopt, start, last))) { @@ -486,8 +487,11 @@ static int iopt_unmap_iova_range(struct io_pagetable *iopt, unsigned long start, area->prevent_access = true; up_write(&iopt->iova_rwsem); up_read(&iopt->domains_rwsem); - /* Later patch calls back to drivers to unmap */ - return -EBUSY; + iommufd_access_notify_unmap(iopt, area_first, + iopt_area_length(area)); + if (WARN_ON(READ_ONCE(area->num_accesses))) + return -EDEADLOCK; + goto again; } pages = area->pages; |