[RFC PATCH v3 07/15] hw/arm/smmuv3: Implement get_viommu_cap() callback

[Shameer Kolothum via]

For accelerated SMMUv3, we need nested parent domain creation. Add the
callback support so that VFIO can create a nested parent.

Since 'accel=on' for SMMUv3 requires the guest SMMUv3 to be configured
in Stage 1 mode, ensure that the 'stage' property is explicitly set to
Stage 1.

Signed-off-by: Shameer Kolothum <shameerali.kolothum.th...@huawei.com>
---
 hw/arm/smmuv3-accel.c | 15 +++++++++++++++
 hw/arm/virt.c         | 12 ++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/hw/arm/smmuv3-accel.c b/hw/arm/smmuv3-accel.c
index 0b0ddb03e2..66cd4f5ece 100644
--- a/hw/arm/smmuv3-accel.c
+++ b/hw/arm/smmuv3-accel.c
@@ -10,6 +10,7 @@
 #include "qemu/error-report.h"
 
 #include "hw/arm/smmuv3.h"
+#include "hw/iommu.h"
 #include "hw/pci/pci_bridge.h"
 #include "hw/pci-host/gpex.h"
 #include "hw/vfio/pci.h"
@@ -81,8 +82,22 @@ static AddressSpace *smmuv3_accel_find_add_as(PCIBus *bus, 
void *opaque,
     }
 }
 
+static uint64_t smmuv3_accel_get_viommu_cap(void *opaque)
+{
+    /*
+     * Accelerated smmuv3 support only allowes Guest S1
+     * configuration. Hence report VIOMMU_CAP_STAGE1
+     * so that VFIO can create nested parent domain.
+     * The real nested support should be reported from host
+     * SMMUv3 and if it doesn't, the nested parent allocation
+     * will fail anyway.
+     */
+    return VIOMMU_CAP_STAGE1;
+}
+
 static const PCIIOMMUOps smmuv3_accel_ops = {
     .get_address_space = smmuv3_accel_find_add_as,
+    .get_viommu_cap = smmuv3_accel_get_viommu_cap,
 };
 
 void smmuv3_accel_init(SMMUv3State *s)
diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 22393cf39e..fdb47eda6a 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -3053,6 +3053,18 @@ static void virt_machine_device_plug_cb(HotplugHandler 
*hotplug_dev,
                 return;
             }
 
+            if (object_property_get_bool(OBJECT(dev), "accel", &error_abort)) {
+                char *stage;
+
+                stage = object_property_get_str(OBJECT(dev), "stage",
+                                                &error_fatal);
+                if (*stage && strcmp("1", stage)) {
+                    error_setg(errp, "Only stage1 is supported for SMMUV3 with 
"
+                               "accel=on");
+                    return;
+                }
+            }
+
             create_smmuv3_dev_dtb(vms, dev, bus);
         }
     }
-- 
2.34.1