diff mbox series

[RFC,v1,3/5] vfio-ccw: Copy CCW data outside length calculation

Message ID 20190618202352.39702-4-farman@linux.ibm.com (mailing list archive)
State New, archived
Headers show
Series s390: more vfio-ccw code rework | expand

Commit Message

Eric Farman June 18, 2019, 8:23 p.m. UTC 
It doesn't make much sense to "hide" the copy to the channel_program
struct inside a routine that calculates the length of the chain.

Let's move it to the calling routine, which will later copy from
channel_program to the memory it allocated itself.

Signed-off-by: Eric Farman <farman@linux.ibm.com>
---
 drivers/s390/cio/vfio_ccw_cp.c | 19 +++++++------------
 1 file changed, 7 insertions(+), 12 deletions(-)

Comments

Cornelia Huck June 19, 2019, 8:18 a.m. UTC | #1 
On Tue, 18 Jun 2019 22:23:50 +0200
Eric Farman <farman@linux.ibm.com> wrote:

> It doesn't make much sense to "hide" the copy to the channel_program
> struct inside a routine that calculates the length of the chain.
> 
> Let's move it to the calling routine, which will later copy from
> channel_program to the memory it allocated itself.
> 
> Signed-off-by: Eric Farman <farman@linux.ibm.com>
> ---
>  drivers/s390/cio/vfio_ccw_cp.c | 19 +++++++------------
>  1 file changed, 7 insertions(+), 12 deletions(-)

Reviewed-by: Cornelia Huck <cohuck@redhat.com>
diff mbox series

Patch

diff --git a/drivers/s390/cio/vfio_ccw_cp.c b/drivers/s390/cio/vfio_ccw_cp.c
index 37d513e86530..a55f8d110920 100644
--- a/drivers/s390/cio/vfio_ccw_cp.c
+++ b/drivers/s390/cio/vfio_ccw_cp.c
@@ -381,18 +381,8 @@  static void ccwchain_cda_free(struct ccwchain *chain, int idx)
 static int ccwchain_calc_length(u64 iova, struct channel_program *cp)
 {
 	struct ccw1 *ccw = cp->guest_cp;
-	int cnt;
+	int cnt = 0;
 
-	/*
-	 * Copy current chain from guest to host kernel.
-	 * Currently the chain length is limited to CCWCHAIN_LEN_MAX (256).
-	 * So copying 2K is enough (safe).
-	 */
-	cnt = copy_ccw_from_iova(cp, ccw, iova, CCWCHAIN_LEN_MAX);
-	if (cnt)
-		return cnt;
-
-	cnt = 0;
 	do {
 		cnt++;
 
@@ -446,7 +436,12 @@  static int ccwchain_handle_ccw(u32 cda, struct channel_program *cp)
 	struct ccwchain *chain;
 	int len;
 
-	/* Copy the chain from cda to cp, and count the CCWs in it */
+	/* Copy 2K (the most we support today) of possible CCWs */
+	len = copy_ccw_from_iova(cp, cp->guest_cp, cda, CCWCHAIN_LEN_MAX);
+	if (len)
+		return len;
+
+	/* Count the CCWs in the current chain */
 	len = ccwchain_calc_length(cda, cp);
 	if (len < 0)
 		return len;