1 files changed, 126 insertions, 0 deletions
diff --git a/drivers/nvdimm/nd_virtio.c b/drivers/nvdimm/nd_virtio.c
new file mode 100644
index 0000000000..1f8c667c6f
--- /dev/null
+++ b/drivers/nvdimm/nd_virtio.c
@@ -0,0 +1,126 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * virtio_pmem.c: Virtio pmem Driver
+ *
+ * Discovers persistent memory range information
+ * from host and provides a virtio based flushing
+ * interface.
+ */
+#include "virtio_pmem.h"
+#include "nd.h"
+
+ /* The interrupt handler */
+void virtio_pmem_host_ack(struct virtqueue *vq)
+{
+	struct virtio_pmem *vpmem = vq->vdev->priv;
+	struct virtio_pmem_request *req_data, *req_buf;
+	unsigned long flags;
+	unsigned int len;
+
+	spin_lock_irqsave(&vpmem->pmem_lock, flags);
+	while ((req_data = virtqueue_get_buf(vq, &len)) != NULL) {
+		req_data->done = true;
+		wake_up(&req_data->host_acked);
+
+		if (!list_empty(&vpmem->req_list)) {
+			req_buf = list_first_entry(&vpmem->req_list,
+					struct virtio_pmem_request, list);
+			req_buf->wq_buf_avail = true;
+			wake_up(&req_buf->wq_buf);
+			list_del(&req_buf->list);
+		}
+	}
+	spin_unlock_irqrestore(&vpmem->pmem_lock, flags);
+}
+EXPORT_SYMBOL_GPL(virtio_pmem_host_ack);
+
+ /* The request submission function */
+static int virtio_pmem_flush(struct nd_region *nd_region)
+{
+	struct virtio_device *vdev = nd_region->provider_data;
+	struct virtio_pmem *vpmem  = vdev->priv;
+	struct virtio_pmem_request *req_data;
+	struct scatterlist *sgs[2], sg, ret;
+	unsigned long flags;
+	int err, err1;
+
+	might_sleep();
+	req_data = kmalloc(sizeof(*req_data), GFP_KERNEL);
+	if (!req_data)
+		return -ENOMEM;
+
+	req_data->done = false;
+	init_waitqueue_head(&req_data->host_acked);
+	init_waitqueue_head(&req_data->wq_buf);
+	INIT_LIST_HEAD(&req_data->list);
+	req_data->req.type = cpu_to_le32(VIRTIO_PMEM_REQ_TYPE_FLUSH);
+	sg_init_one(&sg, &req_data->req, sizeof(req_data->req));
+	sgs[0] = &sg;
+	sg_init_one(&ret, &req_data->resp.ret, sizeof(req_data->resp));
+	sgs[1] = &ret;
+
+	spin_lock_irqsave(&vpmem->pmem_lock, flags);
+	 /*
+	  * If virtqueue_add_sgs returns -ENOSPC then req_vq virtual
+	  * queue does not have free descriptor. We add the request
+	  * to req_list and wait for host_ack to wake us up when free
+	  * slots are available.
+	  */
+	while ((err = virtqueue_add_sgs(vpmem->req_vq, sgs, 1, 1, req_data,
+					GFP_ATOMIC)) == -ENOSPC) {
+
+		dev_info(&vdev->dev, "failed to send command to virtio pmem device, no free slots in the virtqueue\n");
+		req_data->wq_buf_avail = false;
+		list_add_tail(&req_data->list, &vpmem->req_list);
+		spin_unlock_irqrestore(&vpmem->pmem_lock, flags);
+
+		/* A host response results in "host_ack" getting called */
+		wait_event(req_data->wq_buf, req_data->wq_buf_avail);
+		spin_lock_irqsave(&vpmem->pmem_lock, flags);
+	}
+	err1 = virtqueue_kick(vpmem->req_vq);
+	spin_unlock_irqrestore(&vpmem->pmem_lock, flags);
+	/*
+	 * virtqueue_add_sgs failed with error different than -ENOSPC, we can't
+	 * do anything about that.
+	 */
+	if (err || !err1) {
+		dev_info(&vdev->dev, "failed to send command to virtio pmem device\n");
+		err = -EIO;
+	} else {
+		/* A host repsonse results in "host_ack" getting called */
+		wait_event(req_data->host_acked, req_data->done);
+		err = le32_to_cpu(req_data->resp.ret);
+	}
+
+	kfree(req_data);
+	return err;
+};
+
+/* The asynchronous flush callback function */
+int async_pmem_flush(struct nd_region *nd_region, struct bio *bio)
+{
+	/*
+	 * Create child bio for asynchronous flush and chain with
+	 * parent bio. Otherwise directly call nd_region flush.
+	 */
+	if (bio && bio->bi_iter.bi_sector != -1) {
+		struct bio *child = bio_alloc(bio->bi_bdev, 0,
+					      REQ_OP_WRITE | REQ_PREFLUSH,
+					      GFP_ATOMIC);
+
+		if (!child)
+			return -ENOMEM;
+		bio_clone_blkg_association(child, bio);
+		child->bi_iter.bi_sector = -1;
+		bio_chain(child, bio);
+		submit_bio(child);
+		return 0;
+	}
+	if (virtio_pmem_flush(nd_region))
+		return -EIO;
+
+	return 0;
+};
+EXPORT_SYMBOL_GPL(async_pmem_flush);
+MODULE_LICENSE("GPL");