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| author | Robin Murphy <robin.murphy@arm.com> | 2017-01-10 17:51:17 +0000 |
|---|---|---|
| committer | Michael S. Tsirkin <mst@redhat.com> | 2017-01-25 00:33:10 +0200 |
| commit | f7f6634d23830ff74335734fbdb28ea109c1f349 (patch) | |
| tree | 16604be2ced1416e3a2ec61225e4bf484cce0a72 /drivers/virtio/virtio_mmio.c | |
| parent | 0516ffd88fa0d006ee80389ce14a9ca5ae45e845 (diff) | |
| download | lwn-f7f6634d23830ff74335734fbdb28ea109c1f349.tar.gz lwn-f7f6634d23830ff74335734fbdb28ea109c1f349.zip | |
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/virtio_mmio.c')
| -rw-r--r-- | drivers/virtio/virtio_mmio.c | 20 |
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); |