[04/89] intel-iommu: Check for identity mapping candidate using

[Greg KH]

2.6.39-stable review patch.  If anyone has any objections, please let us know.

------------------
 system dma mask

From: Chris Wright <chrisw@xxxxxxxxxxxx>

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@xxxxxxx>
Reviewed-by: Mike Habeck <habeck@xxxxxxx>
Signed-off-by: David Woodhouse <David.Woodhouse@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 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;
 }


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/