[RFC 1/2] target/arm/kvm: Let kvm_arm_vgic_probe() return a bitmap

[Eric Auger <eric.auger@redhat.com>]

Let convert kvm_arm_vgic_probe() so that it returns a
bitmap of supported VGIC versions. This allows to expose
the case where the host GICv3 also supports GICv2 emulation.

Signed-off-by: Eric Auger <eric.auger@redhat.com>
---
 hw/arm/virt.c        | 11 +++++++++--
 target/arm/kvm.c     | 14 ++++++++------
 target/arm/kvm_arm.h |  3 +++
 3 files changed, 20 insertions(+), 8 deletions(-)

diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index e591a126e7..a196bbf0d5 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -1540,11 +1540,18 @@ static void machvirt_init(MachineState *machine)
                 vms->gic_version = 3;
             }
         } else {
-            vms->gic_version = kvm_arm_vgic_probe();
-            if (!vms->gic_version) {
+            int probe_bitmap = kvm_arm_vgic_probe();
+
+            if (!probe_bitmap) {
                 error_report(
                     "Unable to determine GIC version supported by host");
                 exit(1);
+            } else {
+                if (probe_bitmap & KVM_ARM_VGIC_V3) {
+                    vms->gic_version = 3;
+                } else {
+                    vms->gic_version = 2;
+                }
             }
         }
     }
diff --git a/target/arm/kvm.c b/target/arm/kvm.c
index 85860e6f95..390077c518 100644
--- a/target/arm/kvm.c
+++ b/target/arm/kvm.c
@@ -874,15 +874,17 @@ int kvm_arch_irqchip_create(KVMState *s)
 
 int kvm_arm_vgic_probe(void)
 {
+    int val = 0;
+
     if (kvm_create_device(kvm_state,
                           KVM_DEV_TYPE_ARM_VGIC_V3, true) == 0) {
-        return 3;
-    } else if (kvm_create_device(kvm_state,
-                                 KVM_DEV_TYPE_ARM_VGIC_V2, true) == 0) {
-        return 2;
-    } else {
-        return 0;
+        val |= KVM_ARM_VGIC_V3;
     }
+    if (kvm_create_device(kvm_state,
+                          KVM_DEV_TYPE_ARM_VGIC_V2, true) == 0) {
+        val |= KVM_ARM_VGIC_V2;
+    }
+    return val;
 }
 
 int kvm_arm_set_irq(int cpu, int irqtype, int irq, int level)
diff --git a/target/arm/kvm_arm.h b/target/arm/kvm_arm.h
index ae9e075d75..48bf5e16d5 100644
--- a/target/arm/kvm_arm.h
+++ b/target/arm/kvm_arm.h
@@ -15,6 +15,9 @@
 #include "exec/memory.h"
 #include "qemu/error-report.h"
 
+#define KVM_ARM_VGIC_V2   (1 << 0)
+#define KVM_ARM_VGIC_V3   (1 << 1)
+
 /**
  * kvm_arm_vcpu_init:
  * @cs: CPUState
-- 
2.20.1