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.
From: Chris Wright <chrisw@xxxxxxxxxxxx>
Signed-off-by: Mike Travis <travis@xxxxxxx>
Reviewed-by: Mike Habeck <habeck@xxxxxxx>
---
drivers/pci/intel-iommu.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)
--- linux.orig/drivers/pci/intel-iommu.c
+++ linux/drivers/pci/intel-iommu.c
@@ -2187,8 +2187,19 @@ 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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