[PATCH 1/2] vfio/ccw: Add length to DMA_UNMAP checks

Eric Farman
2022-07-26T15:07:30Z

As pointed out with the simplification of the
VFIO_IOMMU_NOTIFY_DMA_UNMAP notifier [1], the length
parameter was never used to check against the pinned
pages.

Let's correct that, and see if a page is within the
affected range instead of simply the first page of
the range.

[1] https://lore.kernel.org/kvm/20220720170457.39cda0d0.alex.williamson@redhat.com/

Signed-off-by: Eric Farman <farman@linux.ibm.com>
---
drivers/s390/cio/vfio_ccw_cp.c | 11 +++++++----
drivers/s390/cio/vfio_ccw_cp.h | 2 +-
drivers/s390/cio/vfio_ccw_ops.c | 2 +-
3 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/s390/cio/vfio_ccw_cp.c b/drivers/s390/cio/vfio_ccw_cp.c
index 8963f452f963..f15b5114abd1 100644
--- a/drivers/s390/cio/vfio_ccw_cp.c
+++ b/drivers/s390/cio/vfio_ccw_cp.c
@@ -170,12 +170,14 @@ static void page_array_unpin_free(struct page_array *pa, struct vfio_device *vde
kfree(pa->pa_iova);
}

-static bool page_array_iova_pinned(struct page_array *pa, unsigned long iova)
+static bool page_array_iova_pinned(struct page_array *pa, unsigned long iova,
+ unsigned long length)
{
int i;

for (i = 0; i < pa->pa_nr; i++)
- if (pa->pa_iova[i] == iova)
+ if (pa->pa_iova[i] >= iova &&
+ pa->pa_iova[i] <= iova + length)
return true;

return false;
@@ -899,11 +901,12 @@ void cp_update_scsw(struct channel_program *cp, union scsw *scsw)
* cp_iova_pinned() - check if an iova is pinned for a ccw chain.
* @cp: channel_program on which to perform the operation
* @iova: the iova to check
+ * @length: the length to check from @iova
*
* If the @iova is currently pinned for the ccw chain, return true;
* else return false.
*/
-bool cp_iova_pinned(struct channel_program *cp, u64 iova)
+bool cp_iova_pinned(struct channel_program *cp, u64 iova, u64 length)
{
struct ccwchain *chain;
int i;
@@ -913,7 +916,7 @@ bool cp_iova_pinned(struct channel_program *cp, u64 iova)

list_for_each_entry(chain, &cp->ccwchain_list, next) {
for (i = 0; i < chain->ch_len; i++)
- if (page_array_iova_pinned(chain->ch_pa + i, iova))
+ if (page_array_iova_pinned(chain->ch_pa + i, iova, length))
return true;
}

diff --git a/drivers/s390/cio/vfio_ccw_cp.h b/drivers/s390/cio/vfio_ccw_cp.h
index 3194d887e08e..54d26e242533 100644
--- a/drivers/s390/cio/vfio_ccw_cp.h
+++ b/drivers/s390/cio/vfio_ccw_cp.h
@@ -46,6 +46,6 @@ void cp_free(struct channel_program *cp);
int cp_prefetch(struct channel_program *cp);
union orb *cp_get_orb(struct channel_program *cp, u32 intparm, u8 lpm);
void cp_update_scsw(struct channel_program *cp, union scsw *scsw);
-bool cp_iova_pinned(struct channel_program *cp, u64 iova);
+bool cp_iova_pinned(struct channel_program *cp, u64 iova, u64 length);

#endif
diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c
index 0047fd88f938..3f67fa103c7f 100644
--- a/drivers/s390/cio/vfio_ccw_ops.c
+++ b/drivers/s390/cio/vfio_ccw_ops.c
@@ -39,7 +39,7 @@ static void vfio_ccw_dma_unmap(struct vfio_device *vdev, u64 iova, u64 length)
container_of(vdev, struct vfio_ccw_private, vdev);

/* Drivers MUST unpin pages in response to an invalidation. */
- if (!cp_iova_pinned(&private->cp, iova))
+ if (!cp_iova_pinned(&private->cp, iova, length))
return;

vfio_ccw_mdev_reset(private);
--
2.34.1