[PATCH] virtio_mmio: Set DMA masks appropriately
From: arnd@arndb.de (Arnd Bergmann)
Date: 2017-01-10 13:15:57
Also in:
virtualization
On Tuesday, January 10, 2017 12:26:01 PM CET Robin Murphy wrote:
quoted hunk ↗ jump to hunk
@@ -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));
You don't seem to do anything different when 64-bit DMA is unsupported. How do you prevent the use of kernel buffers that are above the first 4G here?
+ else if (vm_dev->version == 1) + dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(32 + PAGE_SHIFT));
Why is this limitation only for the coherent mask? Arnd