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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>
This commit is contained in:
Chris Wright 2011-05-28 13:15:02 -05:00 committed by David Woodhouse
parent 9b4554b21e
commit 8fcc5372fb
1 changed files with 13 additions and 2 deletions
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15
drivers/pci/intel-iommu.c
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@ -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;
}