Messages in this thread Patch in this message | | | Date | Wed, 15 Jun 2011 16:59:27 -0700 | From | Greg KH <> | Subject | [04/89] intel-iommu: Check for identity mapping candidate using |
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2.6.39-stable review patch. If anyone has any objections, please let us know.
------------------ system dma mask
From: Chris Wright <chrisw@sous-sol.org>
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 <travis@sgi.com> Reviewed-by: Mike Habeck <habeck@sgi.com> Signed-off-by: David Woodhouse <David.Woodhouse@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- drivers/pci/intel-iommu.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-)
--- a/drivers/pci/intel-iommu.c +++ b/drivers/pci/intel-iommu.c @@ -2190,8 +2190,19 @@ static int iommu_should_identity_map(str * 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; }
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