diff mbox

[v7,09/13] vfio/ccw: get irqs info and set the eventfd fd

Message ID 20170505020352.8984-10-bjsdjshi@linux.vnet.ibm.com
State New
Headers show

Commit Message

Dong Jia Shi May 5, 2017, 2:03 a.m. UTC 
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 | 103 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 103 insertions(+)

Comments

Eric Auger May 9, 2017, 8:21 a.m. UTC | #1 
Hi,

On 05/05/2017 04:03, 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>
Reviewed-by: Eric Auger <eric.auger@redhat.com>

Thanks

Eric

> ---
>  hw/vfio/ccw.c | 103 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 103 insertions(+)
> 
> diff --git a/hw/vfio/ccw.c b/hw/vfio/ccw.c
> index 7ddcfd7..6760cee 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 +56,99 @@ 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_errno(errp, errno, "vfio: Error getting irq info");
> +        goto get_error;
> +    }
> +
> +    if (event_notifier_init(&vcdev->io_notifier, 0)) {
> +        error_setg_errno(errp, errno,
> +                         "vfio: Unable to init event notifier for IO");
> +        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: %m");
> +    }
> +
> +    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;
> @@ -173,8 +268,15 @@ static void vfio_ccw_realize(DeviceState *dev, Error **errp)
>          goto out_region_err;
>      }
>  
> +    vfio_ccw_register_io_notifier(vcdev, &err);
> +    if (err) {
> +        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 +297,7 @@ 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 May 9, 2017, 8:35 a.m. UTC | #2 
* Auger Eric <eric.auger@redhat.com> [2017-05-09 10:21:15 +0200]:

Hi Eric,

> Hi,
> 
> On 05/05/2017 04:03, 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>
> Reviewed-by: Eric Auger <eric.auger@redhat.com>

Thanks for all of your R-Bs! I will add them in next version. :>

> 
> Thanks
> 
> Eric
> 

[...]
Alex Williamson May 11, 2017, 9:49 p.m. UTC | #3 
On Fri,  5 May 2017 04:03:48 +0200
Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com> 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 | 103 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 103 insertions(+)
> 
> diff --git a/hw/vfio/ccw.c b/hw/vfio/ccw.c
> index 7ddcfd7..6760cee 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 +56,99 @@ 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_errno(errp, errno, "vfio: Error getting irq info");
> +        goto get_error;
> +    }
> +
> +    if (event_notifier_init(&vcdev->io_notifier, 0)) {
> +        error_setg_errno(errp, errno,
> +                         "vfio: Unable to init event notifier for IO");
> +        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;


nit, unnecessary goto here.  set_error label is unused if removed.

Otherwise,

Acked-by: Alex Williamson <alex.williamson@redhat.com>


> +    }
> +
> +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: %m");
> +    }
> +
> +    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;
> @@ -173,8 +268,15 @@ static void vfio_ccw_realize(DeviceState *dev, Error **errp)
>          goto out_region_err;
>      }
>  
> +    vfio_ccw_register_io_notifier(vcdev, &err);
> +    if (err) {
> +        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 +297,7 @@ 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 May 15, 2017, 2:31 a.m. UTC | #4 
* Alex Williamson <alex.williamson@redhat.com> [2017-05-11 15:49:04 -0600]:

Hi Alex,

[...]

> > diff --git a/hw/vfio/ccw.c b/hw/vfio/ccw.c
> > index 7ddcfd7..6760cee 100644
> > --- a/hw/vfio/ccw.c
> > +++ b/hw/vfio/ccw.c

[...]

> > +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_errno(errp, errno, "vfio: Error getting irq info");
> > +        goto get_error;
> > +    }
> > +
> > +    if (event_notifier_init(&vcdev->io_notifier, 0)) {
> > +        error_setg_errno(errp, errno,
> > +                         "vfio: Unable to init event notifier for IO");
> > +        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;
> 
> 
> nit, unnecessary goto here.  set_error label is unused if removed.
Ok, I will remove both this goto line and the set_error label line!

> 
> Otherwise,
> 
> Acked-by: Alex Williamson <alex.williamson@redhat.com>
> 
> 
Thanks for all of your A-Bs! I will add them in next version.

> > +    }
> > +
> > +set_error:
> > +    g_free(irq_set);
> > +
> > +get_error:
> > +    g_free(irq_info);
> > +}
> > +

[...]
Dong Jia Shi May 15, 2017, 2:35 a.m. UTC | #5 
* Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com> [2017-05-15 10:31:48 +0800]:

> * Alex Williamson <alex.williamson@redhat.com> [2017-05-11 15:49:04 -0600]:
> 
> Hi Alex,
> 
> [...]
> 
> > > diff --git a/hw/vfio/ccw.c b/hw/vfio/ccw.c
> > > index 7ddcfd7..6760cee 100644
> > > --- a/hw/vfio/ccw.c
> > > +++ b/hw/vfio/ccw.c
> 
> [...]
> 
> > > +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_errno(errp, errno, "vfio: Error getting irq info");
> > > +        goto get_error;
> > > +    }
> > > +
> > > +    if (event_notifier_init(&vcdev->io_notifier, 0)) {
> > > +        error_setg_errno(errp, errno,
> > > +                         "vfio: Unable to init event notifier for IO");
> > > +        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;
> > 
> > 
> > nit, unnecessary goto here.  set_error label is unused if removed.
> Ok, I will remove both this goto line and the set_error label line!
> 
And rename get_error to out_free_info, which is the more reasonable
label name to me. :>

> > 
> > Otherwise,
> > 
> > Acked-by: Alex Williamson <alex.williamson@redhat.com>
> > 
> > 
> Thanks for all of your A-Bs! I will add them in next version.
> 
> > > +    }
> > > +
> > > +set_error:
> > > +    g_free(irq_set);
> > > +
> > > +get_error:
> > > +    g_free(irq_info);
> > > +}
> > > +
> 
> [...]
> 
> -- 
> Dong Jia Shi
diff mbox

Patch

diff --git a/hw/vfio/ccw.c b/hw/vfio/ccw.c
index 7ddcfd7..6760cee 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 +56,99 @@  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_errno(errp, errno, "vfio: Error getting irq info");
+        goto get_error;
+    }
+
+    if (event_notifier_init(&vcdev->io_notifier, 0)) {
+        error_setg_errno(errp, errno,
+                         "vfio: Unable to init event notifier for IO");
+        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: %m");
+    }
+
+    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;
@@ -173,8 +268,15 @@  static void vfio_ccw_realize(DeviceState *dev, Error **errp)
         goto out_region_err;
     }
 
+    vfio_ccw_register_io_notifier(vcdev, &err);
+    if (err) {
+        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 +297,7 @@  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);