From: Halil Pasic <pasic@linux.ibm.com>
Date: Fri, 26 Apr 2019 20:32:37 +0200
Subject: virtio/s390: DMA support for virtio-ccw
Git-commit: f35f54f11f7f96dc6d43fa79c4a7297a9115627f
Patch-mainline: v5.2-rc1
References: jsc#SLE-6197 FATE#327012 bsc#1140559 LTC#173150

Currently virtio-ccw devices do not work if the device has
VIRTIO_F_IOMMU_PLATFORM. In future we do want to support DMA API with
virtio-ccw.

Let us do the plumbing, so the feature VIRTIO_F_IOMMU_PLATFORM works
with virtio-ccw.

Let us also switch from legacy avail/used accessors to the DMA aware
ones (even if it isn't strictly necessary), and remove the legacy
accessors (we were the last users).

Signed-off-by: Halil Pasic <pasic@linux.ibm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/s390/virtio/virtio_ccw.c |   16 +++++++++++++---
 include/linux/virtio.h           |   17 -----------------
 2 files changed, 13 insertions(+), 20 deletions(-)

--- a/drivers/s390/virtio/virtio_ccw.c
+++ b/drivers/s390/virtio/virtio_ccw.c
@@ -69,6 +69,7 @@ struct virtio_ccw_device {
 	bool device_lost;
 	unsigned int config_ready;
 	void *airq_info;
+	u64 dma_mask;
 };
 
 struct vq_info_block_legacy {
@@ -542,8 +543,8 @@ static struct virtqueue *virtio_ccw_setu
 		info->info_block->s.desc = queue;
 		info->info_block->s.index = i;
 		info->info_block->s.num = info->num;
-		info->info_block->s.avail = (__u64)virtqueue_get_avail(vq);
-		info->info_block->s.used = (__u64)virtqueue_get_used(vq);
+		info->info_block->s.avail = (__u64)virtqueue_get_avail_addr(vq);
+		info->info_block->s.used = (__u64)virtqueue_get_used_addr(vq);
 		ccw->count = sizeof(info->info_block->s);
 	}
 	ccw->cmd_code = CCW_CMD_SET_VQ;
@@ -1233,6 +1234,16 @@ static int virtio_ccw_online(struct ccw_
 		ret = -ENOMEM;
 		goto out_free;
 	}
+
+	vcdev->vdev.dev.parent = &cdev->dev;
+	cdev->dev.dma_mask = &vcdev->dma_mask;
+	/* we are fine with common virtio infrastructure using 64 bit DMA */
+	ret = dma_set_mask_and_coherent(&cdev->dev, DMA_BIT_MASK(64));
+	if (ret) {
+		dev_warn(&cdev->dev, "Failed to enable 64-bit DMA.\n");
+		goto out_free;
+	}
+
 	vcdev->config_block = kzalloc(sizeof(*vcdev->config_block),
 				   GFP_DMA | GFP_KERNEL);
 	if (!vcdev->config_block) {
@@ -1247,7 +1258,6 @@ static int virtio_ccw_online(struct ccw_
 
 	vcdev->is_thinint = virtio_ccw_use_airq; /* at least try */
 
-	vcdev->vdev.dev.parent = &cdev->dev;
 	vcdev->vdev.dev.release = virtio_ccw_release_dev;
 	vcdev->vdev.config = &virtio_ccw_config_ops;
 	vcdev->cdev = cdev;
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -89,23 +89,6 @@ dma_addr_t virtqueue_get_desc_addr(struc
 dma_addr_t virtqueue_get_avail_addr(struct virtqueue *vq);
 dma_addr_t virtqueue_get_used_addr(struct virtqueue *vq);
 
-/*
- * Legacy accessors -- in almost all cases, these are the wrong functions
- * to use.
- */
-static inline void *virtqueue_get_desc(struct virtqueue *vq)
-{
-	return virtqueue_get_vring(vq)->desc;
-}
-static inline void *virtqueue_get_avail(struct virtqueue *vq)
-{
-	return virtqueue_get_vring(vq)->avail;
-}
-static inline void *virtqueue_get_used(struct virtqueue *vq)
-{
-	return virtqueue_get_vring(vq)->used;
-}
-
 /**
  * virtio_device - representation of a device using virtio
  * @index: unique position on the virtio bus