Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 4.9 61/66] virtio_mmio: Set DMA masks appropriately | Date | Tue, 31 Jan 2017 06:37:05 +0100 |
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4.9-stable review patch. If anyone has any objections, please let me know.
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From: Robin Murphy <robin.murphy@arm.com>
commit f7f6634d23830ff74335734fbdb28ea109c1f349 upstream.
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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- drivers/virtio/virtio_mmio.c | 20 +++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-)
--- 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 plat struct virtio_mmio_device *vm_dev; struct resource *mem; unsigned long magic; + int rc; mem = platform_get_resource(pdev, IORESOURCE_MEM, 0); if (!mem) @@ -545,9 +547,25 @@ static int virtio_mmio_probe(struct plat } 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);
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