Re: [PATCH RFC v2 08/12] vfio/ccw: get io region info

[Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>]

* Alex Williamson <alex.williamson@redhat.com> [2017-01-17 15:49:34 -0700]:

> On Thu, 12 Jan 2017 08:25:09 +0100
> Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com> wrote:
> 
> > vfio-ccw provides an MMIO region for I/O operations. We fetch its
> > information via ioctls here, then we can use it performing I/O
> > instructions and retrieving I/O results later on.
> > 
> > Signed-off-by: Xiao Feng Ren <renxiaof@linux.vnet.ibm.com>
> > ---
> >  hw/vfio/ccw.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 52 insertions(+)
> > 
> > diff --git a/hw/vfio/ccw.c b/hw/vfio/ccw.c
> > index 881010b..93394c2 100644
> > --- a/hw/vfio/ccw.c
> > +++ b/hw/vfio/ccw.c
> > @@ -21,11 +21,15 @@
> >  #include "hw/vfio/vfio-common.h"
> >  #include "hw/s390x/s390-ccw.h"
> >  #include "hw/s390x/ccw-device.h"
> > +#include "standard-headers/asm-s390/vfio_ccw.h"
> >  
> >  #define TYPE_VFIO_CCW "vfio-ccw"
> >  typedef struct VFIOCCWDevice {
> >      S390CCWDevice cdev;
> >      VFIODevice vdev;
> > +    uint64_t io_region_size;
> > +    uint64_t io_region_offset;
> > +    struct ccw_io_region *io_region;
> >  } VFIOCCWDevice;
> >  
> >  static void vfio_ccw_compute_needs_reset(VFIODevice *vdev)
> > @@ -50,6 +54,46 @@ static void vfio_ccw_reset(DeviceState *dev)
> >      ioctl(vcdev->vdev.fd, VFIO_DEVICE_RESET);
> >  }
> >  
> > +static void vfio_ccw_get_region(VFIOCCWDevice *vcdev, Error **errp)
> > +{
> > +    VFIODevice *vdev = &vcdev->vdev;
> > +    struct vfio_region_info *info;
> > +    int ret;
> > +
> > +    /* Sanity check device */
> > +    if (!(vdev->flags & VFIO_DEVICE_FLAGS_CCW)) {
> > +        error_setg(errp, "vfio: Um, this isn't a vfio-ccw device");
> > +        return;
> > +    }
> > +
> > +    if (vdev->num_regions != VFIO_CCW_NUM_REGIONS) {
> > +        error_setg(errp, "vfio: Unexpected number of the I/O region %u",
> > +                   vdev->num_regions);
> > +        return;
> > +    }
> 
> I think you want < here, not !=, otherwise you we can never add another
> region to describe something new on a vfio-ccw device without breaking
> this code.  You've defined in the uapi that region index zero is always
> VFIO_CCW_CONFIG_REGION_INDEX and this code only depends on that, no
> matter what additional regions might be added.  That's done below.
> 
Right! Thanks for pointing out. I will fix.

> > +
> > +    ret = vfio_get_region_info(vdev, VFIO_CCW_CONFIG_REGION_INDEX, &info);
> > +    if (ret) {
> > +        error_setg(errp, "vfio: Error getting config info: %d", ret);
> > +        return;
> > +    }
> > +
> > +    vcdev->io_region_size = info->size;
> > +    if (sizeof(*vcdev->io_region) != vcdev->io_region_size) {
> > +        error_setg(errp, "vfio: Unexpected size of the I/O region");
> > +        return;
> > +    }
> > +    vcdev->io_region_offset = info->offset;
> > +    vcdev->io_region = g_malloc0(info->size);
> > +
> > +    g_free(info);
> > +}
> > +
> > +static void vfio_ccw_put_region(VFIOCCWDevice *vcdev)
> > +{
> > +    g_free(vcdev->io_region);
> > +}
> > +
> >  static void vfio_put_device(VFIOCCWDevice *vcdev)
> >  {
> >      g_free(vcdev->vdev.name);
> > @@ -144,8 +188,15 @@ static void vfio_ccw_realize(DeviceState *dev, Error **errp)
> >          goto out_device_err;
> >      }
> >  
> > +    vfio_ccw_get_region(vcdev, errp);
> > +    if (*errp) {
> > +        goto out_region_err;
> > +    }
> > +
> >      return;
> >  
> > +out_region_err:
> > +    vfio_put_device(vcdev);
> >  out_device_err:
> >      vfio_ccw_put_group(group, path);
> >  out_group_err:
> > @@ -166,6 +217,7 @@ static void vfio_ccw_unrealize(DeviceState *dev, Error **errp)
> >          cdc->unrealize(cdev, errp);
> >      }
> >  
> > +    vfio_ccw_put_region(vcdev);
> >      vfio_put_device(vcdev);
> >      vfio_put_group(group);
> >  }
> 

-- 
Dong Jia