For a nested SMMUv3, the ATS capaiblity is decided by the underlying HW,
and then reflected in the IDR0 register of the vSMMU.

The IORT on the other hand could allow it to be always enabled, relying
on the guest-level SMMU kernel driver to disable ATS feature if the ATS
bit isn't set in IDR0.

Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
 hw/arm/virt-acpi-build.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
index 6d8b9aea42..c4cf1caf22 100644
--- a/hw/arm/virt-acpi-build.c
+++ b/hw/arm/virt-acpi-build.c
@@ -485,7 +485,11 @@ build_iort(GArray *table_data, BIOSLinker *linker, VirtMachineState *vms)
     /* Table 15 Memory Access Flags */
     build_append_int_noprefix(table_data, 0x3 /* CCA = CPM = DACS = 1 */, 1);
 
-    build_append_int_noprefix(table_data, 0, 4); /* ATS Attribute */
+    if (vms->iommu == VIRT_IOMMU_NESTED_SMMUV3) {
+        build_append_int_noprefix(table_data, 1, 4); /* ATS Attribute */
+    } else {
+        build_append_int_noprefix(table_data, 0, 4); /* ATS Attribute */
+    }
     /* MCFG pci_segment */
     build_append_int_noprefix(table_data, 0, 4); /* PCI Segment number */
 
-- 
2.43.0