On 2020-09-09 06:32, Srinath Mannam wrote:
Fix IOVA reserve failure for memory regions listed in dma-ranges in the
following cases.
- start address of memory region is 0x0.
That's fair enough, and in fact generalises to the case of zero-sized
gaps between regions, which is indeed an oversight.
- end address of a memory region is equal to start address of next memory
region.
This part doesn't make much sense, however - if the regions described in
bridge->dma_ranges overlap, that's a bug in whoever created a malformed
list to begin with. Possibly it's just poor wording, and you're using
"memory regions" to refer to any or all of the dma_ranges, the reserved
IOVA ranges, and what "start" and "end" in this function represent which
isn't quite either of those.
Fixes: aadad097cd46f ("iommu/dma: Reserve IOVA for PCIe inaccessible DMA
address")
Signed-off-by: Srinath Mannam <srinath.man...@broadcom.com>
---
drivers/iommu/dma-iommu.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)
diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 5141d49a046b..0a3f67a4f9ae 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -213,14 +213,21 @@ static int iova_reserve_pci_windows(struct pci_dev *dev,
resource_list_for_each_entry(window, &bridge->dma_ranges) {
end = window->res->start - window->offset;
resv_iova:
+ if (end < start) {
+ /* dma_ranges list should be sorted */
+ dev_err(&dev->dev, "Failed to reserve IOVA\n");
+ return -EINVAL;
+ }
+ /*
+ * Skip the cases when start address of first memory region is
+ * 0x0 and end address of one memory region and start address
+ * of next memory region are equal. Reserve IOVA for rest of
+ * addresses fall in between given memory ranges.
+ */
if (end > start) {
lo = iova_pfn(iovad, start);
hi = iova_pfn(iovad, end);
reserve_iova(iovad, lo, hi);
- } else {
Surely this only needs to be a one-liner?
- } else {
+ } else if (end < start) {
(or possibly "end != start"; I can't quite decide which expresses the
semantic intent better)
The rest just looks like unnecessary churn - I don't think it needs
commenting that a sorted list may simply not have gaps between entries,
and as above I think the wording of that comment is actively misleading.
Robin.
- /* dma_ranges list should be sorted */
- dev_err(&dev->dev, "Failed to reserve IOVA\n");
- return -EINVAL;
}
start = window->res->end - window->offset + 1;
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