From: Chris Wright Date: Sat, 28 May 2011 18:15:02 +0000 (-0500) Subject: intel-iommu: Check for identity mapping candidate using system dma mask X-Git-Tag: v2.6.39.2~86 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=001a5287ce15ac855136d9912ba3a71e40befa0a;p=thirdparty%2Fkernel%2Fstable.git intel-iommu: Check for identity mapping candidate using system dma mask commit 8fcc5372fbac085199d84a880503ed67aba3fe49 upstream. 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 Reviewed-by: Mike Habeck Signed-off-by: David Woodhouse Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c index 0eeb797d508e6..ca1346e3eedfd 100644 --- a/drivers/pci/intel-iommu.c +++ b/drivers/pci/intel-iommu.c @@ -2190,8 +2190,19 @@ 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; }