From 001a5287ce15ac855136d9912ba3a71e40befa0a Mon Sep 17 00:00:00 2001 From: Chris Wright Date: Sat, 28 May 2011 13:15:02 -0500 Subject: [PATCH] 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 --- drivers/pci/intel-iommu.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c index 0eeb797d508e..ca1346e3eedf 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; } -- 2.39.5