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

Dong Jia Shi
2017-05-05T02:03:48Z

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;
+ }
+
+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);
--
2.10.2