commit: 8fcc5372fbac085199d84a880503ed67aba3fe49 From: Chris Wright <[email protected]> Date: Sat, 28 May 2011 13:15:02 -0500 Subject: [PATCH] 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 <[email protected]> Reviewed-by: Mike Habeck <[email protected]> Cc: [email protected] Signed-off-by: David Woodhouse <[email protected]> --- drivers/pci/intel-iommu.c | 15 +++++++++++++-- 1 files changed, 13 insertions(+), 2 deletions(-) diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c index 4eaec2f..dcf051d 100644 --- a/drivers/pci/intel-iommu.c +++ b/drivers/pci/intel-iommu.c @@ -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; } _______________________________________________ stable mailing list [email protected] http://linux.kernel.org/mailman/listinfo/stable
