Hi,
On 04/10/2023 15:55, Stewart Hildebrand wrote:
A device tree node for a PCIe root controller may have an iommu-map property [1]
with a phandle reference to the SMMU node, but not necessarily an iommus
property. In this case, we want to treat it the same as we currently handle
devices with an iommus property: don't pass the iommu related properties to
hwdom.
[1]
https://www.kernel.org/doc/Documentation/devicetree/bindings/pci/pci-iommu.txt
Reported-by: Michal Orzel <[email protected]>
Signed-off-by: Stewart Hildebrand <[email protected]>
Acked-by: Julien Grall <[email protected]>
---
v4->v5:
* new patch
---
xen/arch/arm/domain_build.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index 24c9019cc43c..7da254709d17 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -1135,6 +1135,8 @@ static int __init write_properties(struct domain *d,
struct kernel_info *kinfo,
* should be skipped.
*/
iommu_node = dt_parse_phandle(node, "iommus", 0);
+ if ( !iommu_node )
+ iommu_node = dt_parse_phandle(node, "iommu-map", 1);
if ( iommu_node && device_get_class(iommu_node) != DEVICE_IOMMU )
iommu_node = NULL;
I was looking at the history to understand why we decided to not always
hide the properties.
AFAICT, this was mainly to avoid removing the master properties but
keeping the IOMMU nodes in the DT. However, in reality, I don't expect
the IOMMU to function properly in dom0 (in particular when grants are
used for DMA).
Looking at the bindings, it turns out that all the IOMMU using the
generic bindigns would contain the property #iommu-cells. So we could
remove any device with such property.
This would not work for IOMMU bindings not using the generic one. AFAIK,
this is only legacy SMMUv{1,2} binding so we could filter them by
compatible.
With that we would unconditionally remove the properties iommu-* and
avoid increasing the complexity.
Any thoughts?
Cheers,
--
Julien Grall
