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authorRobin Murphy <robin.murphy@arm.com>2017-01-10 17:51:17 +0000
committerMichael S. Tsirkin <mst@redhat.com>2017-01-25 00:33:10 +0200
commitf7f6634d23830ff74335734fbdb28ea109c1f349 (patch)
tree16604be2ced1416e3a2ec61225e4bf484cce0a72 /drivers/virtio
parent0516ffd88fa0d006ee80389ce14a9ca5ae45e845 (diff)
downloadlinux-f7f6634d23830ff74335734fbdb28ea109c1f349.tar.bz2
virtio_mmio: Set DMA masks appropriately
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"). Cc: Andy Lutomirski <luto@kernel.org> Cc: Michael S. Tsirkin <mst@redhat.com> Reported-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com> Fixes: b42111382f0e ("virtio_mmio: Use the DMA API if enabled") Signed-off-by: Robin Murphy <robin.murphy@arm.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Diffstat (limited to 'drivers/virtio')
-rw-r--r--drivers/virtio/virtio_mmio.c20
1 files changed, 19 insertions, 1 deletions
diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
index d47a2fcef818..c71fde5fe835 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>
@@ -498,6 +499,7 @@ 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)
@@ -547,9 +549,25 @@ static int virtio_mmio_probe(struct platform_device *pdev)
}
vm_dev->vdev.id.vendor = readl(vm_dev->base + VIRTIO_MMIO_VENDOR_ID);
- if (vm_dev->version == 1)
+ if (vm_dev->version == 1) {
writel(PAGE_SIZE, vm_dev->base + VIRTIO_MMIO_GUEST_PAGE_SIZE);
+ rc = dma_set_mask(&pdev->dev, DMA_BIT_MASK(64));
+ /*
+ * In the legacy case, ensure our coherently-allocated virtio
+ * ring will be at an address expressable as a 32-bit PFN.
+ */
+ if (!rc)
+ dma_set_coherent_mask(&pdev->dev,
+ DMA_BIT_MASK(32 + PAGE_SHIFT));
+ } else {
+ 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));
+ 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);