[PATCH] virtio_mmio: Set DMA masks appropriately
From: Robin Murphy <robin.murphy@arm.com>
Date: 2017-01-10 12:26:01
Subsystem:
the rest, virtio core · Maintainers:
Linus Torvalds, "Michael S. Tsirkin", Jason Wang
Once DMA API usage is enabled, it becomes apparent that virtio-mmio is
inadvertently relying on the default 32-bit DMA mask, which leads to
problems like rapidly exhausting SWIOTLB bounce buffers.
Ensure that we set the appropriate 64-bit DMA mask whenever possible,
with the coherent mask suitably limited for the legacy vring as per
a0be1db4304f ("virtio_pci: Limit DMA mask to 44 bits for legacy virtio
devices").
Reported-by: Jean-Philippe Brucker <redacted>
Fixes: b42111382f0e ("virtio_mmio: Use the DMA API if enabled")
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
---
drivers/virtio/virtio_mmio.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
index 48bfea91dbca..b5c5d49ca598 100644
--- a/drivers/virtio/virtio_mmio.c
+++ b/drivers/virtio/virtio_mmio.c@@ -59,6 +59,7 @@ #define pr_fmt(fmt) "virtio-mmio: " fmt #include <linux/acpi.h> +#include <linux/dma-mapping.h> #include <linux/highmem.h> #include <linux/interrupt.h> #include <linux/io.h>
@@ -497,6 +498,7 @@ static int virtio_mmio_probe(struct platform_device *pdev) struct virtio_mmio_device *vm_dev; struct resource *mem; unsigned long magic; + int rc; mem = platform_get_resource(pdev, IORESOURCE_MEM, 0); if (!mem)
@@ -548,6 +550,14 @@ static int virtio_mmio_probe(struct platform_device *pdev) if (vm_dev->version == 1) writel(PAGE_SIZE, vm_dev->base + VIRTIO_MMIO_GUEST_PAGE_SIZE); + rc = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64)); + if (rc) + rc = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32)); + else if (vm_dev->version == 1) + dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(32 + PAGE_SHIFT)); + if (rc) + dev_warn(&pdev->dev, "Failed to enable 64-bit or 32-bit DMA. Trying to continue, but this might not work.\n"); + platform_set_drvdata(pdev, vm_dev); return register_virtio_device(&vm_dev->vdev);
--
2.10.2.dirty