On 28/02/2023 8:21 pm, Sven Peter wrote:
The USB4 PCIe DARTs claim to support bypass but we never want to allow
that on externally facing ports.
IOMMU drivers shouldn't be implementing their own individual policies
for this - externally-facing ports should be correctly marked as
such[1], so that the PCI layer is properly informed, which in turn will
be picked up and handled properly by IOMMU core code.
Thanks,
Robin.
[1] see Documentation/devicetree/bindings/pci/pci.txt
Acked-by: Hector Martin <marcan@xxxxxxxxx>
Signed-off-by: Sven Peter <sven@xxxxxxxxxxxxx>
---
drivers/iommu/apple-dart.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/drivers/iommu/apple-dart.c b/drivers/iommu/apple-dart.c
index 42666617803d..7d8b2b90cdb6 100644
--- a/drivers/iommu/apple-dart.c
+++ b/drivers/iommu/apple-dart.c
@@ -182,6 +182,8 @@ struct apple_dart_hw {
u64 ttbr_addr_field_shift;
u64 ttbr_shift;
int ttbr_count;
+
+ bool disable_bypass;
};
/*
@@ -1075,6 +1077,9 @@ static int apple_dart_probe(struct platform_device *pdev)
dart->pgsize = 1 << FIELD_GET(DART_PARAMS1_PAGE_SHIFT, dart_params[0]);
dart->supports_bypass = dart_params[1] & DART_PARAMS2_BYPASS_SUPPORT;
+ if (dart->hw->disable_bypass)
+ dart->supports_bypass = 0;
+
switch (dart->hw->type) {
case DART_T8020:
case DART_T6000:
