Implement get_viommu_cap() callback and expose stage-1 capability for now.

VFIO uses it to create nested parent domain which is further used to create
nested domain in vIOMMU. All these will be implemented in following patches.

Suggested-by: Yi Liu <yi.l.liu@intel.com>
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
---
 hw/i386/intel_iommu.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
index 04809bd776..e3b871de70 100644
--- a/hw/i386/intel_iommu.c
+++ b/hw/i386/intel_iommu.c
@@ -24,6 +24,7 @@
 #include "qemu/main-loop.h"
 #include "qapi/error.h"
 #include "hw/sysbus.h"
+#include "hw/iommu.h"
 #include "intel_iommu_internal.h"
 #include "hw/pci/pci.h"
 #include "hw/pci/pci_bus.h"
@@ -4423,6 +4424,16 @@ static void vtd_dev_unset_iommu_device(PCIBus *bus, void *opaque, int devfn)
     vtd_iommu_unlock(s);
 }
 
+static uint64_t vtd_get_viommu_cap(void *opaque)
+{
+    IntelIOMMUState *s = opaque;
+    uint64_t caps;
+
+    caps = s->flts ? VIOMMU_CAP_HW_NESTED : 0;
+
+    return caps;
+}
+
 /* Unmap the whole range in the notifier's scope. */
 static void vtd_address_space_unmap(VTDAddressSpace *as, IOMMUNotifier *n)
 {
@@ -4853,6 +4864,7 @@ static PCIIOMMUOps vtd_iommu_ops = {
     .register_iotlb_notifier = vtd_register_iotlb_notifier,
     .unregister_iotlb_notifier = vtd_unregister_iotlb_notifier,
     .ats_request_translation = vtd_ats_request_translation,
+    .get_viommu_cap = vtd_get_viommu_cap,
 };
 
 static bool vtd_decide_config(IntelIOMMUState *s, Error **errp)
-- 
2.47.1

On Fri, Aug 22, 2025 at 02:40:41AM -0400, Zhenzhong Duan wrote:
> Implement get_viommu_cap() callback and expose stage-1 capability for now.
> 
> VFIO uses it to create nested parent domain which is further used to create
> nested domain in vIOMMU. All these will be implemented in following patches.
> 
> Suggested-by: Yi Liu <yi.l.liu@intel.com>
> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
> Reviewed-by: Eric Auger <eric.auger@redhat.com>
 
Reviewed-by: Nicolin Chen <nicolinc@nvidia.com>