[PULL,7/7] s390/cio: Remove vfio-ccw checks of command codes
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Message ID 20190603105038.11788-8-cohuck@redhat.com
State New
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  • [PULL,1/7] s390/cio: Update SCSW if it points to the end of the chain
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Commit Message

Cornelia Huck June 3, 2019, 10:50 a.m. UTC
From: Eric Farman <farman@linux.ibm.com>

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>
 drivers/s390/cio/vfio_ccw_cp.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff mbox series

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);