If a ccw has CCW_FLAG_SKIP set, and the command is of type
read, read backwards, or sense, no data should be written
to the guest for that command.
Signed-off-by: Cornelia Huck <coh...@redhat.com>
---
v2 -> v3: fixed checks even more [Pierre]
v1 -> v2: fixed checks for command type [Eric]
---
hw/s390x/css.c | 22 ++++++++++++++++++----
include/hw/s390x/css.h | 1 +
2 files changed, 19 insertions(+), 4 deletions(-)
diff --git a/hw/s390x/css.c b/hw/s390x/css.c
index 8fc9e35ba5d3..0fbaa233ffb5 100644
--- a/hw/s390x/css.c
+++ b/hw/s390x/css.c
@@ -830,8 +830,12 @@ static int ccw_dstream_rw_noflags(CcwDataStream *cds, void
*buff, int len,
if (op == CDS_OP_A) {
goto incr;
}
- ret = address_space_rw(&address_space_memory, cds->cda,
- MEMTXATTRS_UNSPECIFIED, buff, len, op);
+ if (!cds->do_skip) {
+ ret = address_space_rw(&address_space_memory, cds->cda,
+ MEMTXATTRS_UNSPECIFIED, buff, len, op);
+ } else {
+ ret = 0;
+ }
if (ret != MEMTX_OK) {
cds->flags |= CDS_F_STREAM_BROKEN;
return -EINVAL;
@@ -928,8 +932,13 @@ static int ccw_dstream_rw_ida(CcwDataStream *cds, void
*buff, int len,
do {
iter_len = MIN(len, cont_left);
if (op != CDS_OP_A) {
- ret = address_space_rw(&address_space_memory, cds->cda,
- MEMTXATTRS_UNSPECIFIED, buff, iter_len, op);
+ if (!cds->do_skip) {
+ ret = address_space_rw(&address_space_memory, cds->cda,
+ MEMTXATTRS_UNSPECIFIED, buff, iter_len,
+ op);
+ } else {
+ ret = 0;
+ }
if (ret != MEMTX_OK) {
/* assume inaccessible address */
ret = -EINVAL; /* channel program check */
@@ -968,6 +977,11 @@ void ccw_dstream_init(CcwDataStream *cds, CCW1 const *ccw,
ORB const *orb)
cds->count = ccw->count;
cds->cda_orig = ccw->cda;
+ /* skip is only effective for read, read backwards, or sense commands */
+ cds->do_skip = (ccw->flags & CCW_FLAG_SKIP) &&
+ ((ccw->cmd_code & 0x0f) == CCW_CMD_BASIC_SENSE ||
+ (ccw->cmd_code & 0x03) == 0x02 /* read */ ||
+ (ccw->cmd_code & 0x0f) == 0x0c /* read backwards */);
ccw_dstream_rewind(cds);
if (!(cds->flags & CDS_F_IDA)) {
cds->op_handler = ccw_dstream_rw_noflags;
diff --git a/include/hw/s390x/css.h b/include/hw/s390x/css.h
index aae19c427229..7cc183ef4366 100644
--- a/include/hw/s390x/css.h
+++ b/include/hw/s390x/css.h
@@ -97,6 +97,7 @@ typedef struct CcwDataStream {
int (*op_handler)(struct CcwDataStream *cds, void *buff, int len,
CcwDataStreamOp op);
hwaddr cda;
+ bool do_skip;
} CcwDataStream;
/*
--
2.20.1
