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Subject[PATCH 3/4] Intel pci: Limit dmar_init_reserved_ranges
    dmar_init_reserved_ranges() reserves the card's MMIO ranges to
prevent handing out a DMA map that would overlap with the MMIO range.
The problem while the Nvidia GPU has 64bit BARs, it's capable of
receiving > 40bit PIOs, but can't generate > 40bit DMAs.

So when the iommu code reserves these MMIO ranges a > 40bit
entry ends up getting in the rbtree. On a UV test system with
the Nvidia cards, the BARs are:

0001:36:00.0 VGA compatible controller: nVidia Corporation GT200GL
Region 0: Memory at 92000000 (32-bit, non-prefetchable) [size=16M]
Region 1: Memory at f8200000000 (64-bit, prefetchable) [size=256M]
Region 3: Memory at 90000000 (64-bit, non-prefetchable) [size=32M]

So this 44bit MMIO address 0xf8200000000 ends up in the rbtree. As DMA
maps get added and deleted from the rbtree we can end up getting a cached
entry to this 0xf8200000000 entry... this is what results in the code
handing out the invalid DMA map of 0xf81fffff000:

[ 0xf8200000000-1 >> PAGE_SIZE << PAGE_SIZE ]

The IOVA code needs to better honor the "limit_pfn" when allocating
these maps.

Signed-off-by: Mike Travis <>
Reviewed-by: Mike Habeck <>
drivers/pci/intel-iommu.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- linux.orig/drivers/pci/intel-iommu.c
+++ linux/drivers/pci/intel-iommu.c
@@ -1323,7 +1323,8 @@ static void dmar_init_reserved_ranges(vo

for (i = 0; i < PCI_NUM_RESOURCES; i++) {
r = &pdev->resource[i];
- if (!r->flags || !(r->flags & IORESOURCE_MEM))
+ if (!r->flags || !(r->flags & IORESOURCE_MEM) ||
+ r->start > pdev->dma_mask)
iova = reserve_iova(&reserved_iova_list,

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