vfio-ccw: Skip second copy of guest cp to host

We already pinned/copied/unpinned 2K (256 CCWs) of guest memory
to the host space anchored off vfio_ccw_private.  There's no need
to do that again once we have the length calculated, when we could
just copy the section we need to the "permanent" space for the I/O.

Signed-off-by: Eric Farman <farman@linux.ibm.com>
Message-Id: <20190618202352.39702-3-farman@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Farhan Ali <alifm@linux.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>

diff --git a/drivers/s390/cio/vfio_ccw_cp.c b/drivers/s390/cio/vfio_ccw_cp.c
index f358502..37d513e 100644 (file)
--- a/drivers/s390/cio/vfio_ccw_cp.c
+++ b/drivers/s390/cio/vfio_ccw_cp.c
@@ -444,7 +444,7 @@ static int ccwchain_loop_tic(struct ccwchain *chain,
 static int ccwchain_handle_ccw(u32 cda, struct channel_program *cp)
 {
        struct ccwchain *chain;
-       int len, ret;
+       int len;
 
        /* Copy the chain from cda to cp, and count the CCWs in it */
        len = ccwchain_calc_length(cda, cp);
@@ -457,12 +457,8 @@ static int ccwchain_handle_ccw(u32 cda, struct channel_program *cp)
                return -ENOMEM;
        chain->ch_iova = cda;
 
-       /* Copy the new chain from user. */
-       ret = copy_ccw_from_iova(cp, chain->ch_ccw, cda, len);
-       if (ret) {
-               ccwchain_free(chain);
-               return ret;
-       }
+       /* Copy the actual CCWs into the new chain */
+       memcpy(chain->ch_ccw, cp->guest_cp, len * sizeof(struct ccw1));
 
        /* Loop for tics on this new chain. */
        return ccwchain_loop_tic(chain, cp);