Commit 8fcc5372 authored May 28, 2011 by Chris Wright Committed by David Woodhouse Jun 01, 2011

intel-iommu: Check for identity mapping candidate using system dma mask



The identity mapping code appears to make the assumption that if the
devices dma_mask is greater than 32bits the device can use identity
mapping.  But that is not true: take the case where we have a 40bit
device in a 44bit architecture. The device can potentially receive a
physical address that it will truncate and cause incorrect addresses
to be used.

Instead check to see if the device's dma_mask is large enough
to address the system's dma_mask.

Signed-off-by: Mike Travis <travis@sgi.com>
Reviewed-by: Mike Habeck <habeck@sgi.com>
Cc: stable@kernel.org
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

parent 9b4554b2

drivers/pci/intel-iommu.c

+13 −2

Original line number	Diff line number	Diff line
		@@ -2316,8 +2316,19 @@ static int iommu_should_identity_map(struct pci_dev *pdev, int startup)
		* Assume that they will -- if they turn out not to be, then we can
		* take them out of the 1:1 domain later.
		*/
		if (!startup)
		return pdev->dma_mask > DMA_BIT_MASK(32);
		if (!startup) {
		/*
		* If the device's dma_mask is less than the system's memory
		* size then this is not a candidate for identity mapping.
		*/
		u64 dma_mask = pdev->dma_mask;

		if (pdev->dev.coherent_dma_mask &&
		pdev->dev.coherent_dma_mask < dma_mask)
		dma_mask = pdev->dev.coherent_dma_mask;

		return dma_mask >= dma_get_required_mask(&pdev->dev);
		}

		return 1;
		}