[PATCH RFC v2 09/12] vfio/ccw: get irqs info and set the eventfd fd

Dong Jia Shi
2017-01-12T07:25:10Z

From: Xiao Feng Ren <renxiaof@linux.vnet.ibm.com>

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: Xiao Feng Ren <renxiaof@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 93394c2..c6bfce7 100644
--- a/hw/vfio/ccw.c
+++ b/hw/vfio/ccw.c
@@ -21,6 +21,7 @@
#include "hw/vfio/vfio-common.h"
#include "hw/s390x/s390-ccw.h"
#include "hw/s390x/ccw-device.h"
+#include "qemu/error-report.h"
#include "standard-headers/asm-s390/vfio_ccw.h"

#define TYPE_VFIO_CCW "vfio-ccw"
@@ -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_NUM_IRQS) {
+ 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");
+ goto get_error;
+ }
+
+ if (event_notifier_init(&vcdev->io_notifier, 0)) {
+ error_setg(errp, "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");
+ }
+
+ 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;
@@ -193,8 +287,15 @@ static void vfio_ccw_realize(DeviceState *dev, Error **errp)
goto out_region_err;
}

+ vfio_ccw_register_io_notifier(vcdev, errp);
+ if (*errp) {
+ goto out_notifier_err;
+ }
+
return;

+out_notifier_err:
+ vfio_ccw_put_region(vcdev);
out_region_err:
vfio_put_device(vcdev);
out_device_err:
@@ -217,6 +318,7 @@ static void vfio_ccw_unrealize(DeviceState *dev, Error **errp)
cdc->unrealize(cdev, errp);
}

+ vfio_ccw_unregister_io_notifier(vcdev);
vfio_ccw_put_region(vcdev);
vfio_put_device(vcdev);
vfio_put_group(group);
--
2.8.4