[PATCH v3 2/2] vfio-ccw: Wire in the request callback

Eric Farman
2020-12-03T21:36:07Z

The device is being unplugged, so pass the request to userspace to
ask for a graceful cleanup. This should free up the thread that
would otherwise loop waiting for the device to be fully released.

Signed-off-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
---
drivers/s390/cio/vfio_ccw_ops.c | 26 ++++++++++++++++++++++++++
drivers/s390/cio/vfio_ccw_private.h | 4 ++++
include/uapi/linux/vfio.h | 1 +
3 files changed, 31 insertions(+)

diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c
index 8b3ed5b45277..68106be4ba7a 100644
--- a/drivers/s390/cio/vfio_ccw_ops.c
+++ b/drivers/s390/cio/vfio_ccw_ops.c
@@ -394,6 +394,7 @@ static int vfio_ccw_mdev_get_irq_info(struct vfio_irq_info *info)
switch (info->index) {
case VFIO_CCW_IO_IRQ_INDEX:
case VFIO_CCW_CRW_IRQ_INDEX:
+ case VFIO_CCW_REQ_IRQ_INDEX:
info->count = 1;
info->flags = VFIO_IRQ_INFO_EVENTFD;
break;
@@ -424,6 +425,9 @@ static int vfio_ccw_mdev_set_irqs(struct mdev_device *mdev,
case VFIO_CCW_CRW_IRQ_INDEX:
ctx = &private->crw_trigger;
break;
+ case VFIO_CCW_REQ_IRQ_INDEX:
+ ctx = &private->req_trigger;
+ break;
default:
return -EINVAL;
}
@@ -607,6 +611,27 @@ static ssize_t vfio_ccw_mdev_ioctl(struct mdev_device *mdev,
}
}

+/* Request removal of the device*/
+static void vfio_ccw_mdev_request(struct mdev_device *mdev, unsigned int count)
+{
+ struct vfio_ccw_private *private = dev_get_drvdata(mdev_parent_dev(mdev));
+
+ if (!private)
+ return;
+
+ if (private->req_trigger) {
+ if (!(count % 10))
+ dev_notice_ratelimited(mdev_dev(private->mdev),
+ "Relaying device request to user (#%u)\n",
+ count);
+
+ eventfd_signal(private->req_trigger, 1);
+ } else if (count == 0) {
+ dev_notice(mdev_dev(private->mdev),
+ "No device request channel registered, blocked until released by user\n");
+ }
+}
+
static const struct mdev_parent_ops vfio_ccw_mdev_ops = {
.owner = THIS_MODULE,
.supported_type_groups = mdev_type_groups,
@@ -617,6 +642,7 @@ static const struct mdev_parent_ops vfio_ccw_mdev_ops = {
.read = vfio_ccw_mdev_read,
.write = vfio_ccw_mdev_write,
.ioctl = vfio_ccw_mdev_ioctl,
+ .request = vfio_ccw_mdev_request,
};

int vfio_ccw_mdev_reg(struct subchannel *sch)
diff --git a/drivers/s390/cio/vfio_ccw_private.h b/drivers/s390/cio/vfio_ccw_private.h
index 8723156b29ea..b2c762eb42b9 100644
--- a/drivers/s390/cio/vfio_ccw_private.h
+++ b/drivers/s390/cio/vfio_ccw_private.h
@@ -84,7 +84,10 @@ struct vfio_ccw_crw {
* @irb: irb info received from interrupt
* @scsw: scsw info
* @io_trigger: eventfd ctx for signaling userspace I/O results
+ * @crw_trigger: eventfd ctx for signaling userspace CRW information
+ * @req_trigger: eventfd ctx for signaling userspace to return device
* @io_work: work for deferral process of I/O handling
+ * @crw_work: work for deferral process of CRW handling
*/
struct vfio_ccw_private {
struct subchannel *sch;
@@ -108,6 +111,7 @@ struct vfio_ccw_private {

struct eventfd_ctx *io_trigger;
struct eventfd_ctx *crw_trigger;
+ struct eventfd_ctx *req_trigger;
struct work_struct io_work;
struct work_struct crw_work;
} __aligned(8);
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 2f313a238a8f..d1812777139f 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -820,6 +820,7 @@ enum {
enum {
VFIO_CCW_IO_IRQ_INDEX,
VFIO_CCW_CRW_IRQ_INDEX,
+ VFIO_CCW_REQ_IRQ_INDEX,
VFIO_CCW_NUM_IRQS
};

--
2.17.1