path: root/drivers/s390/cio
diff options
authorEric Farman <farman@linux.ibm.com>2019-05-16 18:14:03 +0200
committerCornelia Huck <cohuck@redhat.com>2019-06-03 12:02:55 +0200
commit9b6e57e5a51696171de990b3c41bd53d4b8ab8ac (patch)
tree1c8eb0b1fe09b72cf400a17ec5b8419258ef45a8 /drivers/s390/cio
parents390/cio: Allow zero-length CCWs in vfio-ccw (diff)
s390/cio: Remove vfio-ccw checks of command codes
If the CCW being processed is a No-Operation, then by definition no data is being transferred. Let's fold those checks into the normal CCW processors, rather than skipping out early. Likewise, if the CCW being processed is a "test" (a category defined here as an opcode that contains zero in the lowest four bits) then no special processing is necessary as far as vfio-ccw is concerned. These command codes have not been valid since the S/370 days, meaning they are invalid in the same way as one that ends in an eight [1] or an otherwise valid command code that is undefined for the device type in question. Considering that, let's just process "test" CCWs like any other CCW, and send everything to the hardware. [1] POPS states that a x08 is a TIC CCW, and that having any high-order bits enabled is invalid for format-1 CCWs. For format-0 CCWs, the high-order bits are ignored. Signed-off-by: Eric Farman <farman@linux.ibm.com> Message-Id: <20190516161403.79053-4-farman@linux.ibm.com> Acked-by: Farhan Ali <alifm@linux.ibm.com> Signed-off-by: Cornelia Huck <cohuck@redhat.com>
Diffstat (limited to 'drivers/s390/cio')
1 files changed, 5 insertions, 6 deletions
diff --git a/drivers/s390/cio/vfio_ccw_cp.c b/drivers/s390/cio/vfio_ccw_cp.c
index c77c9b4cd2a8..f73cfcfdd032 100644
--- a/drivers/s390/cio/vfio_ccw_cp.c
+++ b/drivers/s390/cio/vfio_ccw_cp.c
@@ -295,8 +295,6 @@ static long copy_ccw_from_iova(struct channel_program *cp,
#define ccw_is_read_backward(_ccw) (((_ccw)->cmd_code & 0x0F) == 0x0C)
#define ccw_is_sense(_ccw) (((_ccw)->cmd_code & 0x0F) == CCW_CMD_BASIC_SENSE)
-#define ccw_is_test(_ccw) (((_ccw)->cmd_code & 0x0F) == 0)
#define ccw_is_noop(_ccw) ((_ccw)->cmd_code == CCW_CMD_NOOP)
#define ccw_is_tic(_ccw) ((_ccw)->cmd_code == CCW_CMD_TIC)
@@ -320,6 +318,10 @@ static inline int ccw_does_data_transfer(struct ccw1 *ccw)
if (ccw->count == 0)
return 0;
+ /* If the command is a NOP, then no data will be transferred */
+ if (ccw_is_noop(ccw))
+ return 0;
/* If the skip flag is off, then data will be transferred */
if (!ccw_is_skip(ccw))
return 1;
@@ -404,7 +406,7 @@ static void ccwchain_cda_free(struct ccwchain *chain, int idx)
struct ccw1 *ccw = chain->ch_ccw + idx;
- if (ccw_is_test(ccw) || ccw_is_noop(ccw) || ccw_is_tic(ccw))
+ if (ccw_is_tic(ccw))
kfree((void *)(u64)ccw->cda);
@@ -730,9 +732,6 @@ static int ccwchain_fetch_one(struct ccwchain *chain,
struct ccw1 *ccw = chain->ch_ccw + idx;
- if (ccw_is_test(ccw) || ccw_is_noop(ccw))
- return 0;
if (ccw_is_tic(ccw))
return ccwchain_fetch_tic(chain, idx, cp);