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authorJason Gunthorpe <jgg@mellanox.com>2018-06-29 11:31:50 -0600
committerAlex Williamson <alex.williamson@redhat.com>2018-06-30 13:58:09 -0600
commitbb94b55af3461e26b32f0e23d455abeae0cfca5d (patch)
tree452551a00278b41d599598e1e80eed6b2e7c365b
parent7733e05b34f5d855c5590d816b41ddfee972d188 (diff)
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>
-rw-r--r--drivers/vfio/vfio_iommu_type1.c16
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]);