On Mon, 6 May 2019 16:58:03 -0400 Eric Farman <far...@linux.ibm.com> wrote:
> On 5/6/19 1:17 PM, Cornelia Huck wrote: > > 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> > > --- > > > > Only extremely lightly tested (i.e., can boot a guest.) > > > > --- > > 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..6ee31cc2e08f 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 & CCW_CMD_BASIC_SENSE || > > + ccw->cmd_code & 0x02 /* read */ || > > + ccw->cmd_code & 0x0c /* read backwards */); > > I wish so badly that these checks work, since it'd simplify the vfio-ccw > code, but I don't think this lets you tell the difference between a READ > (x02) and a NOP (x03) or any other control-type CCW. Ditto > read-backward versus TIC. :-( Drat, why is that never easy... I'll rework this check. > > > 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; > > > > /* > > >