On Wed, May 18, 2022 at 5:32 PM Cornelia Huck [off-list ref] wrote:

On Wed, May 18 2022, Jason Wang [off-list ref] wrote:

quoted

This patch tries to implement the synchronize_cbs() for ccw. For the
vring_interrupt() that is called via virtio_airq_handler(), the
synchronization is simply done via the airq_info's lock. For the
vring_interrupt() that is called via virtio_ccw_int_handler(), a per
device rwlock is introduced ans used in the synchronization method.

s/ans/and/

Will fix.

quoted

Cc: Thomas Gleixner <redacted>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Halil Pasic <pasic@linux.ibm.com>
Cc: Cornelia Huck <cohuck@redhat.com>
Cc: Vineeth Vijayan <vneethv@linux.ibm.com>
Cc: Peter Oberparleiter <oberpar@linux.ibm.com>
Cc: linux-s390@vger.kernel.org
Signed-off-by: Jason Wang <redacted>
---
 drivers/s390/virtio/virtio_ccw.c | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/drivers/s390/virtio/virtio_ccw.c b/drivers/s390/virtio/virtio_ccw.c
index d35e7a3f7067..22d36594bcdd 100644
--- a/drivers/s390/virtio/virtio_ccw.c
+++ b/drivers/s390/virtio/virtio_ccw.c

@@ -62,6 +62,7 @@ struct virtio_ccw_device {
      unsigned int revision; /* Transport revision */
      wait_queue_head_t wait_q;
      spinlock_t lock;
+     rwlock_t irq_lock;
      struct mutex io_lock; /* Serializes I/O requests */
      struct list_head virtqueues;
      bool is_thinint;

@@ -984,6 +985,27 @@ static const char *virtio_ccw_bus_name(struct virtio_device *vdev)
      return dev_name(&vcdev->cdev->dev);
 }

+static void virtio_ccw_synchronize_cbs(struct virtio_device *vdev)
+{
+     struct virtio_ccw_device *vcdev = to_vc_device(vdev);
+     struct airq_info *info = vcdev->airq_info;
+
+     if (info) {
+             /*
+              * Synchronize with the vring_interrupt() with airq indicator

Maybe

/*
 * This device uses adapter interrupts: synchronize with
 * vring_interrupt() called by virtio_airq_handler() via the indicator
 * area lock.
 */

Fine.

quoted

+              */
+             write_lock_irq(&info->lock);
+             write_unlock_irq(&info->lock);
+     } else {
+             /*
+              * Synchronize with the vring_interrupt() called by
+              * virtio_ccw_int_handler().

/*
 * This device uses classic interrupts: synchronize with
 * vring_interrupt() called by virtio_ccw_int_handler() via the
 * per-device irq_lock.
 */

Looks fine.

quoted

+              */
+             write_lock_irq(&vcdev->irq_lock);
+             write_unlock_irq(&vcdev->irq_lock);
+     }
+}
+
 static const struct virtio_config_ops virtio_ccw_config_ops = {
      .get_features = virtio_ccw_get_features,
      .finalize_features = virtio_ccw_finalize_features,

@@ -995,6 +1017,7 @@ static const struct virtio_config_ops virtio_ccw_config_ops = {
      .find_vqs = virtio_ccw_find_vqs,
      .del_vqs = virtio_ccw_del_vqs,
      .bus_name = virtio_ccw_bus_name,
+     .synchronize_cbs = virtio_ccw_synchronize_cbs,
 };

@@ -1106,6 +1129,8 @@ static void virtio_ccw_int_handler(struct ccw_device *cdev,
                      vcdev->err = -EIO;
      }
      virtio_ccw_check_activity(vcdev, activity);
+     /* Local interrupt should be disabled at this time */

/* Interrupts are disabled here. */

?

Interrupts enabled here would surely be a bug.

Right.

Thanks

quoted

+     read_lock(&vcdev->irq_lock);
      for_each_set_bit(i, indicators(vcdev),
                       sizeof(*indicators(vcdev)) * BITS_PER_BYTE) {
              /* The bit clear must happen before the vring kick. */

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