Re: [Qemu-devel] [PATCH v6 09/13] vfio/ccw: get irqs info and set the eventfd fd

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

* Auger Eric <eric.auger@redhat.com> [2017-05-01 13:08:45 +0200]:

Hi Eric,

> Hi,
> On 28/04/2017 15:09, Dong Jia Shi wrote:
> > vfio-ccw resorts to the eventfd mechanism to communicate with userspace.
> > We fetch the irqs info via the ioctl VFIO_DEVICE_GET_IRQ_INFO,
> > register a event notifier to get the eventfd fd which is sent
> > to kernel via the ioctl VFIO_DEVICE_SET_IRQS, then we can implement
> > read operation once kernel sends the signal.
> > 
> > Signed-off-by: Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
> > ---
> >  hw/vfio/ccw.c | 102 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 102 insertions(+)
> > 
> > diff --git a/hw/vfio/ccw.c b/hw/vfio/ccw.c
> > index a285b23..cda3057 100644
> > --- a/hw/vfio/ccw.c
> > +++ b/hw/vfio/ccw.c
> > @@ -22,6 +22,7 @@
> >  #include "hw/vfio/vfio-common.h"
> >  #include "hw/s390x/s390-ccw.h"
> >  #include "hw/s390x/ccw-device.h"
> > +#include "qemu/error-report.h"
> >  
> >  #define TYPE_VFIO_CCW "vfio-ccw"
> >  typedef struct VFIOCCWDevice {
> > @@ -30,6 +31,7 @@ typedef struct VFIOCCWDevice {
> >      uint64_t io_region_size;
> >      uint64_t io_region_offset;
> >      struct ccw_io_region *io_region;
> > +    EventNotifier io_notifier;
> >  } VFIOCCWDevice;
> >  
> >  static void vfio_ccw_compute_needs_reset(VFIODevice *vdev)
> > @@ -54,6 +56,98 @@ static void vfio_ccw_reset(DeviceState *dev)
> >      ioctl(vcdev->vdev.fd, VFIO_DEVICE_RESET);
> >  }
> >  
> > +static void vfio_ccw_io_notifier_handler(void *opaque)
> > +{
> > +    VFIOCCWDevice *vcdev = opaque;
> > +
> > +    if (!event_notifier_test_and_clear(&vcdev->io_notifier)) {
> > +        return;
> > +    }
> > +}
> > +
> > +static void vfio_ccw_register_io_notifier(VFIOCCWDevice *vcdev, Error **errp)
> > +{
> > +    VFIODevice *vdev = &vcdev->vdev;
> > +    struct vfio_irq_info *irq_info;
> > +    struct vfio_irq_set *irq_set;
> > +    size_t argsz;
> > +    int32_t *pfd;
> > +
> > +    if (vdev->num_irqs < VFIO_CCW_IO_IRQ_INDEX + 1) {
> > +        error_setg(errp, "vfio: unexpected number of io irqs %u",
> > +                   vdev->num_irqs);
> > +        return;
> > +    }
> > +
> > +    argsz = sizeof(*irq_set);
> > +    irq_info = g_malloc0(argsz);
> > +    irq_info->index = VFIO_CCW_IO_IRQ_INDEX;
> > +    irq_info->argsz = argsz;
> > +    if (ioctl(vdev->fd, VFIO_DEVICE_GET_IRQ_INFO,
> > +              irq_info) < 0 || irq_info->count < 1) {
> > +        error_setg(errp, "vfio: Error getting irq info");
> nit: error_setg_errno?
Ok.

> > +        goto get_error;
> > +    }
> > +
> > +    if (event_notifier_init(&vcdev->io_notifier, 0)) {
> > +        error_setg(errp, "vfio: Unable to init event notifier for IO");
> nit: same
Ok.

> > +        goto get_error;
> > +    }
> > +
> > +    argsz = sizeof(*irq_set) + sizeof(*pfd);
> > +    irq_set = g_malloc0(argsz);
> > +    irq_set->argsz = argsz;
> > +    irq_set->flags = VFIO_IRQ_SET_DATA_EVENTFD |
> > +                     VFIO_IRQ_SET_ACTION_TRIGGER;
> > +    irq_set->index = VFIO_CCW_IO_IRQ_INDEX;
> > +    irq_set->start = 0;
> > +    irq_set->count = 1;
> > +    pfd = (int32_t *) &irq_set->data;
> > +
> > +    *pfd = event_notifier_get_fd(&vcdev->io_notifier);
> > +    qemu_set_fd_handler(*pfd, vfio_ccw_io_notifier_handler, NULL, vcdev);
> > +    if (ioctl(vdev->fd, VFIO_DEVICE_SET_IRQS, irq_set)) {
> > +        error_setg(errp, "vfio: Failed to set up io notification");
> > +        qemu_set_fd_handler(*pfd, NULL, NULL, vcdev);
> > +        event_notifier_cleanup(&vcdev->io_notifier);
> > +        goto set_error;
> > +    }
> > +
> > +set_error:
> > +    g_free(irq_set);
> > +
> > +get_error:
> > +    g_free(irq_info);
> > +}
> > +
> > +static void vfio_ccw_unregister_io_notifier(VFIOCCWDevice *vcdev)
> > +{
> > +    struct vfio_irq_set *irq_set;
> > +    size_t argsz;
> > +    int32_t *pfd;
> > +
> > +    argsz = sizeof(*irq_set) + sizeof(*pfd);
> > +    irq_set = g_malloc0(argsz);
> > +    irq_set->argsz = argsz;
> > +    irq_set->flags = VFIO_IRQ_SET_DATA_EVENTFD |
> > +                     VFIO_IRQ_SET_ACTION_TRIGGER;
> > +    irq_set->index = VFIO_CCW_IO_IRQ_INDEX;
> > +    irq_set->start = 0;
> > +    irq_set->count = 1;
> > +    pfd = (int32_t *) &irq_set->data;
> > +    *pfd = -1;
> > +
> > +    if (ioctl(vcdev->vdev.fd, VFIO_DEVICE_SET_IRQS, irq_set)) {
> > +        error_report("vfio: Failed to de-assign device io fd");
> ditto

error_report("vfio: Failed to de-assign device io fd: %s",
             strerror(drrno));

> > +    }
> > +
> > +    qemu_set_fd_handler(event_notifier_get_fd(&vcdev->io_notifier),
> > +                        NULL, NULL, vcdev);
> > +    event_notifier_cleanup(&vcdev->io_notifier);
> > +
> > +    g_free(irq_set);
> > +}
> > +
> >  static void vfio_ccw_get_region(VFIOCCWDevice *vcdev, Error **errp)
> >  {
> >      VFIODevice *vdev = &vcdev->vdev;
> > @@ -175,8 +269,15 @@ static void vfio_ccw_realize(DeviceState *dev, Error **errp)
> >          goto out_region_err;
> >      }
> >  
> > +    vfio_ccw_register_io_notifier(vcdev, errp);
> > +    if (*errp) {
> ditto
Ok.

> 
> Thanks
> 
> Eric
> > +        goto out_notifier_err;
> > +    }
> > +
> >      return;
> >  
> > +out_notifier_err:
> > +    vfio_ccw_put_region(vcdev);
> >  out_region_err:
> >      vfio_put_device(vcdev);
> >  out_device_err:
> > @@ -195,6 +296,7 @@ static void vfio_ccw_unrealize(DeviceState *dev, Error **errp)
> >      S390CCWDeviceClass *cdc = S390_CCW_DEVICE_GET_CLASS(cdev);
> >      VFIOGroup *group = vcdev->vdev.group;
> >  
> > +    vfio_ccw_unregister_io_notifier(vcdev);
> >      vfio_ccw_put_region(vcdev);
> >      vfio_put_device(vcdev);
> >      vfio_put_group(group);
> > 
> 

-- 
Dong Jia Shi