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authorJohn Hubbard <jhubbard@nvidia.com>2020-01-31 09:12:39 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2020-01-31 21:30:37 +0300
commit3567813eae5e9b4d02dc227e2060e85abc912045 (patch)
tree6126ab93d0bdf9e730601794ca5b9fafe0632291
parentc4237f8b1f4f2857c3079c99f69d971f883dd69c (diff)
downloadlinux-3567813eae5e9b4d02dc227e2060e85abc912045.tar.xz
vfio: fix FOLL_LONGTERM use, simplify get_user_pages_remote() call
Update VFIO to take advantage of the recently loosened restriction on FOLL_LONGTERM with get_user_pages_remote(). Also, now it is possible to fix a bug: the VFIO caller is logically a FOLL_LONGTERM user, but it wasn't setting FOLL_LONGTERM. Also, remove an unnessary pair of calls that were releasing and reacquiring the mmap_sem. There is no need to avoid holding mmap_sem just in order to call page_to_pfn(). Also, now that the the DAX check ("if a VMA is DAX, don't allow long term pinning") is in the internals of get_user_pages_remote() and __gup_longterm_locked(), there's no need for it at the VFIO call site. So remove it. Link: http://lkml.kernel.org/r/20200107224558.2362728-8-jhubbard@nvidia.com Signed-off-by: John Hubbard <jhubbard@nvidia.com> Tested-by: Alex Williamson <alex.williamson@redhat.com> Acked-by: Alex Williamson <alex.williamson@redhat.com> Reviewed-by: Jason Gunthorpe <jgg@mellanox.com> Reviewed-by: Ira Weiny <ira.weiny@intel.com> Suggested-by: Jason Gunthorpe <jgg@ziepe.ca> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Björn Töpel <bjorn.topel@intel.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Hans Verkuil <hverkuil-cisco@xs4all.nl> Cc: Jan Kara <jack@suse.cz> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Leon Romanovsky <leonro@mellanox.com> Cc: Mauro Carvalho Chehab <mchehab@kernel.org> Cc: Mike Rapoport <rppt@linux.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--drivers/vfio/vfio_iommu_type1.c30
1 files changed, 5 insertions, 25 deletions
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 2ada8e6cdb88..b800fc9a0251 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -322,7 +322,6 @@ static int vaddr_get_pfn(struct mm_struct *mm, unsigned long vaddr,
{
struct page *page[1];
struct vm_area_struct *vma;
- struct vm_area_struct *vmas[1];
unsigned int flags = 0;
int ret;
@@ -330,33 +329,14 @@ static int vaddr_get_pfn(struct mm_struct *mm, unsigned long vaddr,
flags |= FOLL_WRITE;
down_read(&mm->mmap_sem);
- if (mm == current->mm) {
- ret = get_user_pages(vaddr, 1, flags | FOLL_LONGTERM, page,
- vmas);
- } else {
- ret = get_user_pages_remote(NULL, mm, vaddr, 1, flags, page,
- vmas, NULL);
- /*
- * The lifetime of a vaddr_get_pfn() page pin is
- * userspace-controlled. In the fs-dax case this could
- * lead to indefinite stalls in filesystem operations.
- * Disallow attempts to pin fs-dax pages via this
- * interface.
- */
- if (ret > 0 && vma_is_fsdax(vmas[0])) {
- ret = -EOPNOTSUPP;
- put_page(page[0]);
- }
- }
- up_read(&mm->mmap_sem);
-
+ ret = get_user_pages_remote(NULL, mm, vaddr, 1, flags | FOLL_LONGTERM,
+ page, NULL, NULL);
if (ret == 1) {
*pfn = page_to_pfn(page[0]);
- return 0;
+ ret = 0;
+ goto done;
}
- down_read(&mm->mmap_sem);
-
vaddr = untagged_addr(vaddr);
vma = find_vma_intersection(mm, vaddr, vaddr + 1);
@@ -366,7 +346,7 @@ static int vaddr_get_pfn(struct mm_struct *mm, unsigned long vaddr,
if (is_invalid_reserved_pfn(*pfn))
ret = 0;
}
-
+done:
up_read(&mm->mmap_sem);
return ret;
}