Re: [Qemu-devel] [PATCH v6 10/13] s390x/css: introduce and realize ccw-request callback

[Auger Eric <eric.auger@redhat.com>]

Hi Dong,

On 28/04/2017 15:09, Dong Jia Shi wrote:
> From: Xiao Feng Ren <renxiaof@linux.vnet.ibm.com>
> 
> Introduce a new callback on subchannel to handle ccw-request.
> Realize the callback in vfio-ccw device. Besides, resort to
> the event notifier handler to handling the ccw-request results.
> 1. Pread the I/O results via MMIO region.
> 2. Update the scsw info to guest.
> 3. Inject an I/O interrupt to notify guest the I/O result.
> 
> Signed-off-by: Xiao Feng Ren <renxiaof@linux.vnet.ibm.com>
> Signed-off-by: Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
> ---
>  hw/s390x/css.c         |  4 +--
>  hw/s390x/s390-ccw.h    |  1 +
>  hw/vfio/ccw.c          | 73 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  include/hw/s390x/css.h |  2 ++
>  4 files changed, 78 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/s390x/css.c b/hw/s390x/css.c
> index 1052eea..507c60f 100644
> --- a/hw/s390x/css.c
> +++ b/hw/s390x/css.c
> @@ -259,7 +259,7 @@ uint16_t css_build_subchannel_id(SubchDev *sch)
>      return css_do_build_subchannel_id(sch->cssid, sch->ssid);
>  }
>  
> -static void css_inject_io_interrupt(SubchDev *sch)
> +void css_inject_io_interrupt(SubchDev *sch)
>  {
>      uint8_t isc = (sch->curr_status.pmcw.flags & PMCW_FLAGS_MASK_ISC) >> 11;
>  
> @@ -668,7 +668,7 @@ static void copy_pmcw_to_guest(PMCW *dest, const PMCW *src)
>      dest->chars = cpu_to_be32(src->chars);
>  }
>  
> -static void copy_scsw_to_guest(SCSW *dest, const SCSW *src)
> +void copy_scsw_to_guest(SCSW *dest, const SCSW *src)
>  {
>      dest->flags = cpu_to_be16(src->flags);
>      dest->ctrl = cpu_to_be16(src->ctrl);
> diff --git a/hw/s390x/s390-ccw.h b/hw/s390x/s390-ccw.h
> index b58d8e9..4e2fa65 100644
> --- a/hw/s390x/s390-ccw.h
> +++ b/hw/s390x/s390-ccw.h
> @@ -27,6 +27,7 @@ typedef struct S390CCWDevice {
>      CcwDevice parent_obj;
>      CssDevId hostid;
>      char *mdevid;
> +    int (*handle_request) (ORB *, SCSW *, void *);
shouldn't this callback be part of the class instead?

>  } S390CCWDevice;
>  
>  typedef struct S390CCWDeviceClass {
> diff --git a/hw/vfio/ccw.c b/hw/vfio/ccw.c
> index cda3057..3ff78c5 100644
> --- a/hw/vfio/ccw.c
> +++ b/hw/vfio/ccw.c
> @@ -47,6 +47,36 @@ struct VFIODeviceOps vfio_ccw_ops = {
>      .vfio_compute_needs_reset = vfio_ccw_compute_needs_reset,
>  };
>  
> +static int vfio_ccw_handle_request(ORB *orb, SCSW *scsw, void *data)
> +{
> +    S390CCWDevice *cdev = data;
> +    VFIOCCWDevice *vcdev = DO_UPCAST(VFIOCCWDevice, cdev, cdev);
> +    struct ccw_io_region *region = vcdev->io_region;
> +    int ret;
> +
> +    QEMU_BUILD_BUG_ON(sizeof(region->orb_area) != sizeof(ORB));
> +    QEMU_BUILD_BUG_ON(sizeof(region->scsw_area) != sizeof(SCSW));
> +    QEMU_BUILD_BUG_ON(sizeof(region->irb_area) != sizeof(IRB));
> +
> +    memset(region, 0, sizeof(*region));
> +
> +    memcpy(region->orb_area, orb, sizeof(ORB));
> +    memcpy(region->scsw_area, scsw, sizeof(SCSW));
> +
> +again:
> +    ret = pwrite(vcdev->vdev.fd, region,
> +                 vcdev->io_region_size, vcdev->io_region_offset);
> +    if (ret != vcdev->io_region_size) {
> +        if (errno == EAGAIN) {
> +            goto again;
> +        }
> +        error_report("vfio-ccw: wirte I/O region failed with errno=%d", errno);
> +        return -errno;
> +    }
> +
> +    return region->ret_code;
> +}
> +
>  static void vfio_ccw_reset(DeviceState *dev)
>  {
>      CcwDevice *ccw_dev = DO_UPCAST(CcwDevice, parent_obj, dev);
> @@ -59,10 +89,52 @@ static void vfio_ccw_reset(DeviceState *dev)
>  static void vfio_ccw_io_notifier_handler(void *opaque)
>  {
>      VFIOCCWDevice *vcdev = opaque;
> +    struct ccw_io_region *region = vcdev->io_region;
> +    S390CCWDevice *cdev = S390_CCW_DEVICE(vcdev);
> +    CcwDevice *ccw_dev = CCW_DEVICE(cdev);
> +    SubchDev *sch = ccw_dev->sch;
> +    SCSW *s = &sch->curr_status.scsw;
> +    IRB irb;
>  
>      if (!event_notifier_test_and_clear(&vcdev->io_notifier)) {
>          return;
>      }
> +
> +    if (pread(vcdev->vdev.fd, region,
> +              vcdev->io_region_size, vcdev->io_region_offset) == -1) {
is it possible to read less bytes than requested?

Thanks

Eric
> +        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);
> +            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 |
> +                    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 |
> +                    SCSW_STCTL_ALERT | SCSW_STCTL_STATUS_PEND;
> +            goto read_err;
> +        }
> +    }
> +
> +    memcpy(&irb, region->irb_area, sizeof(IRB));
> +
> +    /* Update control block via irb. */
> +    copy_scsw_to_guest(s, &irb.scsw);
> +
> +read_err:
> +    css_inject_io_interrupt(sch);
>  }
>  
>  static void vfio_ccw_register_io_notifier(VFIOCCWDevice *vcdev, Error **errp)
> @@ -235,6 +307,7 @@ static void vfio_ccw_realize(DeviceState *dev, Error **errp)
>      VFIOCCWDevice *vcdev = DO_UPCAST(VFIOCCWDevice, cdev, cdev);
>      S390CCWDeviceClass *cdc = S390_CCW_DEVICE_GET_CLASS(cdev);
>  
> +    cdev->handle_request = vfio_ccw_handle_request;
>      /* Call the class init function for subchannel. */
>      if (cdc->realize) {
>          cdc->realize(cdev, vcdev->vdev.sysfsdev, errp);
> diff --git a/include/hw/s390x/css.h b/include/hw/s390x/css.h
> index a8bf1db..c8c283a 100644
> --- a/include/hw/s390x/css.h
> +++ b/include/hw/s390x/css.h
> @@ -135,6 +135,8 @@ void css_subch_assign(uint8_t cssid, uint8_t ssid, uint16_t schid,
>  void css_sch_build_virtual_schib(SubchDev *sch, uint8_t chpid, uint8_t type);
>  int css_sch_build_schib(SubchDev *sch, CssDevId *dev_id);
>  uint16_t css_build_subchannel_id(SubchDev *sch);
> +void copy_scsw_to_guest(SCSW *dest, const SCSW *src);
> +void css_inject_io_interrupt(SubchDev *sch);
>  void css_reset(void);
>  void css_reset_sch(SubchDev *sch);
>  void css_queue_crw(uint8_t rsc, uint8_t erc, int chain, uint16_t rsid);
>