Commit 3567813e authored by John Hubbard's avatar John Hubbard Committed by Linus Torvalds

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.comSigned-off-by: default avatarJohn Hubbard <jhubbard@nvidia.com>
Tested-by: default avatarAlex Williamson <alex.williamson@redhat.com>
Acked-by: default avatarAlex Williamson <alex.williamson@redhat.com>
Reviewed-by: default avatarJason Gunthorpe <jgg@mellanox.com>
Reviewed-by: default avatarIra Weiny <ira.weiny@intel.com>
Suggested-by: default avatarJason 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent c4237f8b
......@@ -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;
}
......
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