On Tue, 5 May 2020 14:57:54 +0200
Eric Farman <far...@linux.ibm.com> wrote:
> From: Farhan Ali <al...@linux.ibm.com>
>
> The schib region can be used to obtain the latest SCHIB from the host
> passthrough subchannel. Since the guest SCHIB is virtualized,
> we currently only update the path related information so that the
> guest is aware of any path related changes when it issues the
> 'stsch' instruction.
>
> Signed-off-by: Farhan Ali <al...@linux.ibm.com>
> Signed-off-by: Eric Farman <far...@linux.ibm.com>
> ---
>
> Notes:
> v1->v2:
> - Remove silly variable intialization, and add a block comment,
> to css_do_stsch() [CH]
> - Add a TODO statement to s390_ccw_store(), for myself to sort
> out while we go over kernel code more closely [CH/EF]
> - In vfio_ccw_handle_store(),
> - Set schib pointer once region is determined to be non-NULL [CH]
> - Return cc=0 if pread() fails, and log an error [CH]
>
> v0->v1: [EF]
> - Change various incarnations of "update chp status" to
> "handle_store", to reflect the STSCH instruction that will
> drive this code
> - Remove temporary variable for casting/testing purposes in
> s390_ccw_store(), and add a block comment of WHY its there.
> - Add a few comments to vfio_ccw_handle_store()
>
> hw/s390x/css.c | 13 ++++++--
> hw/s390x/s390-ccw.c | 21 +++++++++++++
> hw/vfio/ccw.c | 63 +++++++++++++++++++++++++++++++++++++
> include/hw/s390x/css.h | 3 +-
> include/hw/s390x/s390-ccw.h | 1 +
> target/s390x/ioinst.c | 3 +-
> 6 files changed, 99 insertions(+), 5 deletions(-)
>
(...)
>
> +static IOInstEnding vfio_ccw_handle_store(SubchDev *sch)
> +{
> + S390CCWDevice *cdev = sch->driver_data;
> + VFIOCCWDevice *vcdev = DO_UPCAST(VFIOCCWDevice, cdev, cdev);
> + SCHIB *schib = &sch->curr_status;
> + struct ccw_schib_region *region = vcdev->schib_region;
> + SCHIB *s;
> + int ret;
> +
> + /* schib region not available so nothing else to do */
> + if (!region) {
> + return IOINST_CC_EXPECTED;
> + }
> +
> + memset(region, 0, sizeof(*region));
> + ret = pread(vcdev->vdev.fd, region, vcdev->schib_region_size,
> + vcdev->schib_region_offset);
> +
> + if (ret == -1) {
> + /*
> + * Device is probably damaged, but store subchannel does not
> + * have a nonzero cc defined for this scenario. Log an error,
> + * and presume things are otherwise fine.
One thing we might do is set the device number valid bit to 0 in our
local copy and inject a (subchannel) crw. Maybe as a patch on top later.
> + */
> + error_report("vfio-ccw: store region read failed with errno=%d",
> errno);
> + return IOINST_CC_EXPECTED;
> + }
> +
> + /*
> + * Selectively copy path-related bits of the SCHIB,
> + * rather than copying the entire struct.
> + */
> + s = (SCHIB *)region->schib_area;
> + schib->pmcw.pnom = s->pmcw.pnom;
> + schib->pmcw.lpum = s->pmcw.lpum;
> + schib->pmcw.pam = s->pmcw.pam;
> + schib->pmcw.pom = s->pmcw.pom;
> +
> + if (s->scsw.flags & SCSW_FLAGS_MASK_PNO) {
> + schib->scsw.flags |= SCSW_FLAGS_MASK_PNO;
> + }
> +
> + return IOINST_CC_EXPECTED;
> +}
> +
Reviewed-by: Cornelia Huck <coh...@redhat.com>
