[PATCH v2 17/34] vfio: convert put_page() to put_user_page*()

john.hubbard
2019-08-04T22:53:56Z

Note that this effectively changes the code's behavior in
qp_release_pages(): it now ultimately calls set_page_dirty_lock(),
instead of set_page_dirty(). This is probably more accurate.

As Christoph Hellwig put it, "set_page_dirty() is only safe if we are
dealing with a file backed page where we have reference on the inode it
hangs off." [1]

[1] https://lore.kernel.org/r/20190723153640.GB720@lst.de

Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: kvm@vger.kernel.org
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---
drivers/vfio/vfio_iommu_type1.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 054391f30fa8..5a5461a14299 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -320,9 +320,9 @@ static int put_pfn(unsigned long pfn, int prot)
{
if (!is_invalid_reserved_pfn(pfn)) {
struct page *page = pfn_to_page(pfn);
- if (prot & IOMMU_WRITE)
- SetPageDirty(page);
- put_page(page);
+ bool dirty = prot & IOMMU_WRITE;
+
+ put_user_pages_dirty_lock(&page, 1, dirty);
return 1;
}
return 0;
@@ -356,7 +356,7 @@ static int vaddr_get_pfn(struct mm_struct *mm, unsigned long vaddr,
*/
if (ret > 0 && vma_is_fsdax(vmas[0])) {
ret = -EOPNOTSUPP;
- put_page(page[0]);
+ put_user_page(page[0]);
}
}
up_read(&mm->mmap_sem);
--
2.22.0