[PATCH RFC v1 6/7] virtio: use io_tlb_high_mem if it is active

[Dongli Zhang <dongli.zhang@oracle.com>]

When the swiotlb is enforced (e.g., when amd sev is involved), the virito
driver will not be able to use 4+ GB memory. Therefore, the virtio driver
uses 'io_tlb_high_mem' as swiotlb.

Cc: Konrad Wilk <konrad.wilk@oracle.com>
Cc: Joe Jin <joe.jin@oracle.com>
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
---
 drivers/virtio/virtio.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
index ef04a96942bf..d9ebe3940e2d 100644
--- a/drivers/virtio/virtio.c
+++ b/drivers/virtio/virtio.c
@@ -5,6 +5,8 @@
 #include <linux/module.h>
 #include <linux/idr.h>
 #include <linux/of.h>
+#include <linux/swiotlb.h>
+#include <linux/dma-mapping.h>
 #include <uapi/linux/virtio_ids.h>
 
 /* Unique numbering for virtio devices. */
@@ -241,6 +243,12 @@ static int virtio_dev_probe(struct device *_d)
 	u64 device_features;
 	u64 driver_features;
 	u64 driver_features_legacy;
+	struct device *parent = dev->dev.parent;
+	u64 dma_mask = min_not_zero(*parent->dma_mask,
+				    parent->bus_dma_limit);
+
+	if (dma_mask == DMA_BIT_MASK(64))
+		swiotlb_use_high(parent);
 
 	/* We have a driver! */
 	virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER);
-- 
2.17.1