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virtio_mmio: Set DMA masks appropriately

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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
a0be1db430 ("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: b42111382f ("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>
This commit is contained in:
Robin Murphy 2017-01-10 17:51:17 +00:00 committed by Michael S. Tsirkin
parent 0516ffd88f
commit f7f6634d23
1 changed files with 19 additions and 1 deletions
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20
drivers/virtio/virtio_mmio.c
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@ -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);