Commit e1d0b372 authored by Daniel P. Berrangé's avatar Daniel P. Berrangé Committed by Cornelia Huck
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hw/vfio/ccw: avoid taking address members in packed structs 



The GCC 9 compiler complains about many places in s390 code
that take the address of members of the 'struct SCHIB' which
is marked packed:

hw/vfio/ccw.c: In function ‘vfio_ccw_io_notifier_handler’:
hw/vfio/ccw.c:133:15: warning: taking address of packed member of ‘struct SCHIB’ may result in an unaligned pointer value \
[-Waddress-of-packed-member]
  133 |     SCSW *s = &sch->curr_status.scsw;
      |               ^~~~~~~~~~~~~~~~~~~~~~
hw/vfio/ccw.c:134:15: warning: taking address of packed member of ‘struct SCHIB’ may result in an unaligned pointer value \
[-Waddress-of-packed-member]
  134 |     PMCW *p = &sch->curr_status.pmcw;
      |               ^~~~~~~~~~~~~~~~~~~~~~

...snip many more...

Almost all of these are just done for convenience to avoid
typing out long variable/field names when referencing struct
members. We can get most of this convenience by taking the
address of the 'struct SCHIB' instead, avoiding triggering
the compiler warnings.

In a couple of places we copy via a local variable which is
a technique already applied elsewhere in s390 code for this
problem.

Signed-off-by: default avatarDaniel P. Berrangé <berrange@redhat.com>
Message-Id: <20190329111104.17223-12-berrange@redhat.com>
Reviewed-by: default avatarEric Farman <farman@linux.ibm.com>
Reviewed-by: default avatarHalil Pasic <pasic@linux.ibm.com>
Reviewed-by: default avatarFarhan Ali <alifm@linux.ibm.com>
Signed-off-by: default avatarCornelia Huck <cohuck@redhat.com>
parent 061b51e9

hw/vfio/ccw.c

+22 −20
Original line number Diff line number Diff line
@@ -130,8 +130,8 @@ static void vfio_ccw_io_notifier_handler(void *opaque) 
    S390CCWDevice *cdev = S390_CCW_DEVICE(vcdev);

    CcwDevice *ccw_dev = CCW_DEVICE(cdev);

    SubchDev *sch = ccw_dev->sch;

    SCSW *s = &sch->curr_status.scsw;

    PMCW *p = &sch->curr_status.pmcw;

    SCHIB *schib = &sch->curr_status;

    SCSW s;

    IRB irb;

    int size;
@@ -145,33 +145,33 @@ static void vfio_ccw_io_notifier_handler(void *opaque) 
        switch (errno) {

        case ENODEV:

            /* Generate a deferred cc 3 condition. */

            s->flags |= SCSW_FLAGS_MASK_CC;

            s->ctrl &= ~SCSW_CTRL_MASK_STCTL;

            s->ctrl |= (SCSW_STCTL_ALERT | SCSW_STCTL_STATUS_PEND);

            schib->scsw.flags |= SCSW_FLAGS_MASK_CC;

            schib->scsw.ctrl &= ~SCSW_CTRL_MASK_STCTL;

            schib->scsw.ctrl |= (SCSW_STCTL_ALERT | SCSW_STCTL_STATUS_PEND);

            goto read_err;

        case EFAULT:

            /* Memory problem, generate channel data check. */

            s->ctrl &= ~SCSW_ACTL_START_PEND;

            s->cstat = SCSW_CSTAT_DATA_CHECK;

            s->ctrl &= ~SCSW_CTRL_MASK_STCTL;

            s->ctrl |= SCSW_STCTL_PRIMARY | SCSW_STCTL_SECONDARY |

            schib->scsw.ctrl &= ~SCSW_ACTL_START_PEND;

            schib->scsw.cstat = SCSW_CSTAT_DATA_CHECK;

            schib->scsw.ctrl &= ~SCSW_CTRL_MASK_STCTL;

            schib->scsw.ctrl |= SCSW_STCTL_PRIMARY | SCSW_STCTL_SECONDARY |

                       SCSW_STCTL_ALERT | SCSW_STCTL_STATUS_PEND;

            goto read_err;

        default:

            /* Error, generate channel program check. */

            s->ctrl &= ~SCSW_ACTL_START_PEND;

            s->cstat = SCSW_CSTAT_PROG_CHECK;

            s->ctrl &= ~SCSW_CTRL_MASK_STCTL;

            s->ctrl |= SCSW_STCTL_PRIMARY | SCSW_STCTL_SECONDARY |

            schib->scsw.ctrl &= ~SCSW_ACTL_START_PEND;

            schib->scsw.cstat = SCSW_CSTAT_PROG_CHECK;

            schib->scsw.ctrl &= ~SCSW_CTRL_MASK_STCTL;

            schib->scsw.ctrl |= SCSW_STCTL_PRIMARY | SCSW_STCTL_SECONDARY |

                       SCSW_STCTL_ALERT | SCSW_STCTL_STATUS_PEND;

            goto read_err;

        }

    } else if (size != vcdev->io_region_size) {

        /* Information transfer error, generate channel-control check. */

        s->ctrl &= ~SCSW_ACTL_START_PEND;

        s->cstat = SCSW_CSTAT_CHN_CTRL_CHK;

        s->ctrl &= ~SCSW_CTRL_MASK_STCTL;

        s->ctrl |= SCSW_STCTL_PRIMARY | SCSW_STCTL_SECONDARY |

        schib->scsw.ctrl &= ~SCSW_ACTL_START_PEND;

        schib->scsw.cstat = SCSW_CSTAT_CHN_CTRL_CHK;

        schib->scsw.ctrl &= ~SCSW_CTRL_MASK_STCTL;

        schib->scsw.ctrl |= SCSW_STCTL_PRIMARY | SCSW_STCTL_SECONDARY |

                   SCSW_STCTL_ALERT | SCSW_STCTL_STATUS_PEND;

        goto read_err;

    }
@@ -179,11 +179,13 @@ static void vfio_ccw_io_notifier_handler(void *opaque) 
    memcpy(&irb, region->irb_area, sizeof(IRB));



    /* Update control block via irb. */

    copy_scsw_to_guest(s, &irb.scsw);

    s = schib->scsw;

    copy_scsw_to_guest(&s, &irb.scsw);

    schib->scsw = s;



    /* If a uint check is pending, copy sense data. */

    if ((s->dstat & SCSW_DSTAT_UNIT_CHECK) &&

        (p->chars & PMCW_CHARS_MASK_CSENSE)) {

    if ((schib->scsw.dstat & SCSW_DSTAT_UNIT_CHECK) &&

        (schib->pmcw.chars & PMCW_CHARS_MASK_CSENSE)) {

        memcpy(sch->sense_data, irb.ecw, sizeof(irb.ecw));

    }