vfio-ccw: Factor out the ccw0-to-ccw1 transition

This is a really useful function, but it's buried in the
copy_ccw_from_iova() routine so that ccwchain_calc_length()
can just work with Format-1 CCWs while doing its counting.
But it means we're translating a full 2K of "CCWs" to Format-1,
when in reality there's probably far fewer in that space.

Let's factor it out, so maybe we can do something with it later.

Signed-off-by: Eric Farman <farman@linux.ibm.com>
Message-Id: <20190618202352.39702-5-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 a55f8d110920bf782483bda9f0b5acf1876c7333..9a8bf06281e0ebbbda351558065dace03c55aa02 100644 (file)
--- a/drivers/s390/cio/vfio_ccw_cp.c
+++ b/drivers/s390/cio/vfio_ccw_cp.c
@@ -161,6 +161,27 @@ static inline void pfn_array_idal_create_words(
        idaws[0] += pa->pa_iova & (PAGE_SIZE - 1);
 }
 
+void convert_ccw0_to_ccw1(struct ccw1 *source, unsigned long len)
+{
+       struct ccw0 ccw0;
+       struct ccw1 *pccw1 = source;
+       int i;
+
+       for (i = 0; i < len; i++) {
+               ccw0 = *(struct ccw0 *)pccw1;
+               if ((pccw1->cmd_code & 0x0f) == CCW_CMD_TIC) {
+                       pccw1->cmd_code = CCW_CMD_TIC;
+                       pccw1->flags = 0;
+                       pccw1->count = 0;
+               } else {
+                       pccw1->cmd_code = ccw0.cmd_code;
+                       pccw1->flags = ccw0.flags;
+                       pccw1->count = ccw0.count;
+               }
+               pccw1->cda = ccw0.cda;
+               pccw1++;
+       }
+}
 
 /*
  * Within the domain (@mdev), copy @n bytes from a guest physical
@@ -211,32 +232,9 @@ static long copy_ccw_from_iova(struct channel_program *cp,
                               struct ccw1 *to, u64 iova,
                               unsigned long len)
 {
-       struct ccw0 ccw0;
-       struct ccw1 *pccw1;
        int ret;
-       int i;
 
        ret = copy_from_iova(cp->mdev, to, iova, len * sizeof(struct ccw1));
-       if (ret)
-               return ret;
-
-       if (!cp->orb.cmd.fmt) {
-               pccw1 = to;
-               for (i = 0; i < len; i++) {
-                       ccw0 = *(struct ccw0 *)pccw1;
-                       if ((pccw1->cmd_code & 0x0f) == CCW_CMD_TIC) {
-                               pccw1->cmd_code = CCW_CMD_TIC;
-                               pccw1->flags = 0;
-                               pccw1->count = 0;
-                       } else {
-                               pccw1->cmd_code = ccw0.cmd_code;
-                               pccw1->flags = ccw0.flags;
-                               pccw1->count = ccw0.count;
-                       }
-                       pccw1->cda = ccw0.cda;
-                       pccw1++;
-               }
-       }
 
        return ret;
 }
@@ -441,6 +439,10 @@ static int ccwchain_handle_ccw(u32 cda, struct channel_program *cp)
        if (len)
                return len;
 
+       /* Convert any Format-0 CCWs to Format-1 */
+       if (!cp->orb.cmd.fmt)
+               convert_ccw0_to_ccw1(cp->guest_cp, len);
+
        /* Count the CCWs in the current chain */
        len = ccwchain_calc_length(cda, cp);
        if (len < 0)