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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>
This commit is contained in:
Eric Farman 2019-06-18 22:23:49 +02:00 committed by Cornelia Huck
parent 1d897e478d
commit 6246590230
1 changed files with 3 additions and 7 deletions
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10
drivers/s390/cio/vfio_ccw_cp.c
View File

@ -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);