vfio/ccw: populate page_array struct inline

There are two possible ways the list of addresses that get passed
to vfio are calculated. One is from a guest IDAL, which would be
an array of (probably) non-contiguous addresses. The other is
built from contiguous pages that follow the starting address
provided by ccw->cda.

page_array_alloc() attempts to simplify things by pre-populating
this array from the starting address, but that's not needed for
a CCW with an IDAL anyway so doesn't need to be in the allocator.
Move it to the caller in the non-IDAL case, since it will be
overwritten when reading the guest IDAL.

Remove the initialization of the pa_page output pointers,
since it won't be explicitly needed for either case.

Signed-off-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

diff --git a/drivers/s390/cio/vfio_ccw_cp.c b/drivers/s390/cio/vfio_ccw_cp.c
index b1436736b7b683ab0e72d0f34c6291b97cac790e..f448aa93007fd82c388f5e55488b48b71056fa1c 100644 (file)
--- a/drivers/s390/cio/vfio_ccw_cp.c
+++ b/drivers/s390/cio/vfio_ccw_cp.c
@@ -42,7 +42,6 @@ struct ccwchain {
 /*
  * page_array_alloc() - alloc memory for page array
  * @pa: page_array on which to perform the operation
- * @iova: target guest physical address
  * @len: number of pages that should be pinned from @iova
  *
  * Attempt to allocate memory for page array.
@@ -56,10 +55,8 @@ struct ccwchain {
  *   -EINVAL if pa->pa_nr is not initially zero, or pa->pa_iova is not NULL
  *   -ENOMEM if alloc failed
  */
-static int page_array_alloc(struct page_array *pa, u64 iova, unsigned int len)
+static int page_array_alloc(struct page_array *pa, unsigned int len)
 {
-       int i;
-
        if (pa->pa_nr || pa->pa_iova)
                return -EINVAL;
 
@@ -78,13 +75,6 @@ static int page_array_alloc(struct page_array *pa, u64 iova, unsigned int len)
                return -ENOMEM;
        }
 
-       pa->pa_iova[0] = iova;
-       pa->pa_page[0] = NULL;
-       for (i = 1; i < pa->pa_nr; i++) {
-               pa->pa_iova[i] = pa->pa_iova[i - 1] + PAGE_SIZE;
-               pa->pa_page[i] = NULL;
-       }
-
        return 0;
 }
 
@@ -548,7 +538,7 @@ static int ccwchain_fetch_ccw(struct ccw1 *ccw,
         * required for the data transfer, since we only only support
         * 4K IDAWs today.
         */
-       ret = page_array_alloc(pa, iova, idaw_nr);
+       ret = page_array_alloc(pa, idaw_nr);
        if (ret < 0)
                goto out_free_idaws;
 
@@ -565,11 +555,9 @@ static int ccwchain_fetch_ccw(struct ccw1 *ccw,
                for (i = 0; i < idaw_nr; i++)
                        pa->pa_iova[i] = idaws[i];
        } else {
-               /*
-                * No action is required here; the iova addresses in page_array
-                * were initialized sequentially in page_array_alloc() beginning
-                * with the contents of ccw->cda.
-                */
+               pa->pa_iova[0] = iova;
+               for (i = 1; i < pa->pa_nr; i++)
+                       pa->pa_iova[i] = pa->pa_iova[i - 1] + PAGE_SIZE;
        }
 
        if (ccw_does_data_transfer(ccw)) {