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 spinlock for irq is introduced ans used in the synchronization method. Cc: Thomas Gleixner <tglx at linutronix.de> Cc: Peter Zijlstra <peterz at infradead.org> Cc: "Paul E. McKenney" <paulmck at kernel.org> Cc: Marc Zyngier <maz at kernel.org> Cc: Halil Pasic <pasic at linux.ibm.com> Cc: Cornelia Huck <cohuck at redhat.com> Signed-off-by: Jason Wang <jasowang at redhat.com> --- 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..c19f07a82d62 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; + spinlock_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; + + /* + * Synchronize with the vring_interrupt() called by + * virtio_ccw_int_handler(). + */ + spin_lock(&vcdev->irq_lock); + spin_unlock(&vcdev->irq_lock); + + if (info) { + /* + * Synchronize with the vring_interrupt() with airq indicator + */ + write_lock(&info->lock); + write_unlock(&info->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, }; @@ -1079,6 +1102,7 @@ static void virtio_ccw_int_handler(struct ccw_device *cdev, { __u32 activity = intparm & VIRTIO_CCW_INTPARM_MASK; struct virtio_ccw_device *vcdev = dev_get_drvdata(&cdev->dev); + unsigned long flags; int i; struct virtqueue *vq; @@ -1106,6 +1130,7 @@ static void virtio_ccw_int_handler(struct ccw_device *cdev, vcdev->err = -EIO; } virtio_ccw_check_activity(vcdev, activity); + spin_lock_irqsave(&vcdev->irq_lock, flags); for_each_set_bit(i, indicators(vcdev), sizeof(*indicators(vcdev)) * BITS_PER_BYTE) { /* The bit clear must happen before the vring kick. */ @@ -1114,6 +1139,7 @@ static void virtio_ccw_int_handler(struct ccw_device *cdev, vq = virtio_ccw_vq_by_ind(vcdev, i); vring_interrupt(0, vq); } + spin_unlock_irqrestore(&vcdev->irq_lock, flags); if (test_bit(0, indicators2(vcdev))) { virtio_config_changed(&vcdev->vdev); clear_bit(0, indicators2(vcdev)); @@ -1284,6 +1310,7 @@ static int virtio_ccw_online(struct ccw_device *cdev) init_waitqueue_head(&vcdev->wait_q); INIT_LIST_HEAD(&vcdev->virtqueues); spin_lock_init(&vcdev->lock); + spin_lock_init(&vcdev->irq_lock); mutex_init(&vcdev->io_lock); spin_lock_irqsave(get_ccwdev_lock(cdev), flags); -- 2.25.1
Michael S. Tsirkin
2022-Apr-25 08:08 UTC
[PATCH V3 6/9] virtio-ccw: implement synchronize_cbs()
On Mon, Apr 25, 2022 at 10:44:15AM +0800, Jason Wang wrote:> 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 spinlock for irq is introduced ans used in the synchronization > method. > > Cc: Thomas Gleixner <tglx at linutronix.de> > Cc: Peter Zijlstra <peterz at infradead.org> > Cc: "Paul E. McKenney" <paulmck at kernel.org> > Cc: Marc Zyngier <maz at kernel.org> > Cc: Halil Pasic <pasic at linux.ibm.com> > Cc: Cornelia Huck <cohuck at redhat.com> > Signed-off-by: Jason Wang <jasowang at redhat.com>This is the only one that is giving me pause. Halil, Cornelia, should we be concerned about the performance impact here? Any chance it can be tested?> --- > 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..c19f07a82d62 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; > + spinlock_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; > + > + /* > + * Synchronize with the vring_interrupt() called by > + * virtio_ccw_int_handler(). > + */ > + spin_lock(&vcdev->irq_lock); > + spin_unlock(&vcdev->irq_lock); > + > + if (info) { > + /* > + * Synchronize with the vring_interrupt() with airq indicator > + */ > + write_lock(&info->lock); > + write_unlock(&info->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, > }; > > > @@ -1079,6 +1102,7 @@ static void virtio_ccw_int_handler(struct ccw_device *cdev, > { > __u32 activity = intparm & VIRTIO_CCW_INTPARM_MASK; > struct virtio_ccw_device *vcdev = dev_get_drvdata(&cdev->dev); > + unsigned long flags; > int i; > struct virtqueue *vq; > > @@ -1106,6 +1130,7 @@ static void virtio_ccw_int_handler(struct ccw_device *cdev, > vcdev->err = -EIO; > } > virtio_ccw_check_activity(vcdev, activity); > + spin_lock_irqsave(&vcdev->irq_lock, flags); > for_each_set_bit(i, indicators(vcdev), > sizeof(*indicators(vcdev)) * BITS_PER_BYTE) { > /* The bit clear must happen before the vring kick. */ > @@ -1114,6 +1139,7 @@ static void virtio_ccw_int_handler(struct ccw_device *cdev, > vq = virtio_ccw_vq_by_ind(vcdev, i); > vring_interrupt(0, vq); > } > + spin_unlock_irqrestore(&vcdev->irq_lock, flags); > if (test_bit(0, indicators2(vcdev))) { > virtio_config_changed(&vcdev->vdev); > clear_bit(0, indicators2(vcdev)); > @@ -1284,6 +1310,7 @@ static int virtio_ccw_online(struct ccw_device *cdev) > init_waitqueue_head(&vcdev->wait_q); > INIT_LIST_HEAD(&vcdev->virtqueues); > spin_lock_init(&vcdev->lock); > + spin_lock_init(&vcdev->irq_lock); > mutex_init(&vcdev->io_lock); > > spin_lock_irqsave(get_ccwdev_lock(cdev), flags); > -- > 2.25.1