[PATCH v2 03/19] intel_iommu: Implement get_viommu_cap() callback

[Zhenzhong Duan]

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....@intel.com>
Signed-off-by: Zhenzhong Duan <zhenzhong.d...@intel.com>
---
 MAINTAINERS           |  1 +
 include/hw/iommu.h    | 14 ++++++++++++++
 hw/i386/intel_iommu.c | 12 ++++++++++++
 3 files changed, 27 insertions(+)
 create mode 100644 include/hw/iommu.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 94c4076127..27817974a6 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2277,6 +2277,7 @@ F: include/system/iommufd.h
 F: backends/host_iommu_device.c
 F: include/system/host_iommu_device.h
 F: include/qemu/chardev_open.h
+F: include/hw/iommu.h
 F: util/chardev_open.c
 F: docs/devel/vfio-iommufd.rst
 
diff --git a/include/hw/iommu.h b/include/hw/iommu.h
new file mode 100644
index 0000000000..3c1c08f05d
--- /dev/null
+++ b/include/hw/iommu.h
@@ -0,0 +1,14 @@
+/*
+ * General vIOMMU capabilities, flags, etc
+ *
+ * Copyright (C) 2025 Intel Corporation.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#ifndef HW_IOMMU_H
+#define HW_IOMMU_H
+
+#define VIOMMU_CAP_STAGE1    BIT_ULL(0)
+
+#endif /* HW_IOMMU_H */
diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
index f0b1f90eff..702973da5c 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"
@@ -4412,6 +4413,16 @@ 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_STAGE1 : 0;
+
+    return caps;
+}
+
 /* Unmap the whole range in the notifier's scope. */
 static void vtd_address_space_unmap(VTDAddressSpace *as, IOMMUNotifier *n)
 {
@@ -4734,6 +4745,7 @@ static PCIIOMMUOps vtd_iommu_ops = {
     .get_address_space = vtd_host_dma_iommu,
     .set_iommu_device = vtd_dev_set_iommu_device,
     .unset_iommu_device = vtd_dev_unset_iommu_device,
+    .get_viommu_cap = vtd_get_viommu_cap,
 };
 
 static bool vtd_decide_config(IntelIOMMUState *s, Error **errp)
-- 
2.34.1