intel_iommu: Implement get_viommu_flags() callback

Implement get_viommu_flags() callback and expose a request for nesting
parent HWPT for now.

VFIO uses it to create nesting parent HWPT which is further used to create
nested HWPT 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>
Reviewed-by: Yi Liu <yi.l.liu@intel.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Link: https://lore.kernel.org/qemu-devel/20260106061304.314546-7-zhenzhong.duan@intel.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
index 7bec53a58722b3e7cbf02059734b8d1613a94ed1..9ce1bab93c56cd3d303e24be43c6ae1e2c4716a0 100644 (file)
--- 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/core/sysbus.h"
+#include "hw/core/iommu.h"
 #include "intel_iommu_internal.h"
 #include "hw/pci/pci.h"
 #include "hw/pci/pci_bus.h"
@@ -4659,6 +4660,16 @@ static void vtd_dev_unset_iommu_device(PCIBus *bus, void *opaque, int devfn)
     vtd_iommu_unlock(s);
 }
 
+static uint64_t vtd_get_viommu_flags(void *opaque)
+{
+    IntelIOMMUState *s = opaque;
+    uint64_t flags;
+
+    flags = s->fsts ? VIOMMU_FLAG_WANT_NESTING_PARENT : 0;
+
+    return flags;
+}
+
 /* Unmap the whole range in the notifier's scope. */
 static void vtd_address_space_unmap(VTDAddressSpace *as, IOMMUNotifier *n)
 {
@@ -5312,6 +5323,7 @@ static PCIIOMMUOps vtd_iommu_ops = {
     .pri_register_notifier = vtd_pri_register_notifier,
     .pri_unregister_notifier = vtd_pri_unregister_notifier,
     .pri_request_page = vtd_pri_request_page,
+    .get_viommu_flags = vtd_get_viommu_flags,
 };
 
 static bool vtd_decide_config(IntelIOMMUState *s, Error **errp)