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

Alex Williamson
2017-05-11T21:49:04Z

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);