[PATCH] remoteproc: virtio: Add synchronize_cbs to remoteproc_virtio

[Mark-PK Tsai <mark-pk.tsai@xxxxxxxxxxxx>]

Add synchornize_cbs to rproc_virtio_config_ops and a
synchronize_vqs callback to the rproc_ops to ensure vqs'
state changes are visible in vring_interrupts when the vq is
broken or removed.

And when VIRTIO_HARDEN_NOTIFICATION is not set, call
rproc_virtio_synchronize_cbs directly in __rproc_virtio_del_vqs
before virtqueue is free to ensure that rproc_vq_interrupt is
aware of the virtqueue removal.

The synchronized_vqs is expected to be implemented in rproc
driver to ensure that all previous vring_interrupts are handled
before the vqs are marked as broken or removed.

Signed-off-by: Mark-PK Tsai <mark-pk.tsai@xxxxxxxxxxxx>
---
 drivers/remoteproc/remoteproc_virtio.c | 12 ++++++++++++
 include/linux/remoteproc.h             |  4 ++++
 2 files changed, 16 insertions(+)

diff --git a/drivers/remoteproc/remoteproc_virtio.c b/drivers/remoteproc/remoteproc_virtio.c
index d3f39009b28e..e18258b69851 100644
--- a/drivers/remoteproc/remoteproc_virtio.c
+++ b/drivers/remoteproc/remoteproc_virtio.c
@@ -74,6 +74,14 @@ static bool rproc_virtio_notify(struct virtqueue *vq)
 	return true;
 }
 
+static void rproc_virtio_synchronize_cbs(struct virtio_device *vdev)
+{
+	struct rproc *rproc = vdev_to_rproc(vdev);
+
+	if (rproc->ops->synchronize_vqs)
+		rproc->ops->synchronize_vqs(rproc);
+}
+
 /**
  * rproc_vq_interrupt() - tell remoteproc that a virtqueue is interrupted
  * @rproc: handle to the remote processor
@@ -171,6 +179,9 @@ static void __rproc_virtio_del_vqs(struct virtio_device *vdev)
 	list_for_each_entry_safe(vq, n, &vdev->vqs, list) {
 		rvring = vq->priv;
 		rvring->vq = NULL;
+#ifndef CONFIG_VIRTIO_HARDEN_NOTIFICATION
+		rproc_virtio_synchronize_cbs(vdev);
+#endif
 		vring_del_virtqueue(vq);
 	}
 }
@@ -334,6 +345,7 @@ static const struct virtio_config_ops rproc_virtio_config_ops = {
 	.get_status	= rproc_virtio_get_status,
 	.get		= rproc_virtio_get,
 	.set		= rproc_virtio_set,
+	.synchronize_cbs = rproc_virtio_synchronize_cbs,
 };
 
 /*
diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
index b4795698d8c2..73901678ac7d 100644
--- a/include/linux/remoteproc.h
+++ b/include/linux/remoteproc.h
@@ -381,6 +381,9 @@ enum rsc_handling_status {
  * @panic:	optional callback to react to system panic, core will delay
  *		panic at least the returned number of milliseconds
  * @coredump:	  collect firmware dump after the subsystem is shutdown
+ * @synchronize_vqs:	optional callback to guarantee all memory operations
+ *			on the virtqueue before it are visible to the
+ *			rproc_vq_interrupt().
  */
 struct rproc_ops {
 	int (*prepare)(struct rproc *rproc);
@@ -403,6 +406,7 @@ struct rproc_ops {
 	u64 (*get_boot_addr)(struct rproc *rproc, const struct firmware *fw);
 	unsigned long (*panic)(struct rproc *rproc);
 	void (*coredump)(struct rproc *rproc);
+	void (*synchronize_vqs)(struct rproc *rproc);
 };
 
 /**
-- 
2.45.2