diff options
| author | Jason Gunthorpe <jgg@mellanox.com> | 2018-06-29 19:31:50 +0200 |
|---|---|---|
| committer | Alex Williamson <alex.williamson@redhat.com> | 2018-06-30 21:58:09 +0200 |
| commit | bb94b55af3461e26b32f0e23d455abeae0cfca5d (patch) | |
| tree | 452551a00278b41d599598e1e80eed6b2e7c365b /drivers | |
| parent | sample/mdev/mbochs: add mbochs_kunmap_dmabuf (diff) | |
| download | linux-bb94b55af3461e26b32f0e23d455abeae0cfca5d.tar.xz linux-bb94b55af3461e26b32f0e23d455abeae0cfca5d.zip | |
vfio: Use get_user_pages_longterm correctly
The patch noted in the fixes below converted get_user_pages_fast() to
get_user_pages_longterm(), however the two calls differ in a few ways.
First _fast() is documented to not require the mmap_sem, while _longterm()
is documented to need it. Hold the mmap sem as required.
Second, _fast accepts an 'int write' while _longterm uses 'unsigned int
gup_flags', so the expression '!!(prot & IOMMU_WRITE)' is only working by
luck as FOLL_WRITE is currently == 0x1. Use the expected FOLL_WRITE
constant instead.
Fixes: 94db151dc892 ("vfio: disable filesystem-dax page pinning")
Cc: <stable@vger.kernel.org>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Acked-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/vfio/vfio_iommu_type1.c | 16 |
1 files changed, 7 insertions, 9 deletions
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c index 2c75b33db4ac..3e5b17710a4f 100644 --- a/drivers/vfio/vfio_iommu_type1.c +++ b/drivers/vfio/vfio_iommu_type1.c @@ -343,18 +343,16 @@ 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; + if (prot & IOMMU_WRITE) + flags |= FOLL_WRITE; + + down_read(&mm->mmap_sem); if (mm == current->mm) { - ret = get_user_pages_longterm(vaddr, 1, !!(prot & IOMMU_WRITE), - page, vmas); + ret = get_user_pages_longterm(vaddr, 1, flags, page, vmas); } else { - unsigned int flags = 0; - - if (prot & IOMMU_WRITE) - flags |= FOLL_WRITE; - - down_read(&mm->mmap_sem); ret = get_user_pages_remote(NULL, mm, vaddr, 1, flags, page, vmas, NULL); /* @@ -368,8 +366,8 @@ static int vaddr_get_pfn(struct mm_struct *mm, unsigned long vaddr, ret = -EOPNOTSUPP; put_page(page[0]); } - up_read(&mm->mmap_sem); } + up_read(&mm->mmap_sem); if (ret == 1) { *pfn = page_to_pfn(page[0]); |