From: Haibo Xu <haibo.xu@linaro.org>

KVM_CAP_ARM_EL2 must be supported by the cpu to enable ARM_FEATURE_EL2.
In case the host does support NV, expose the feature.

Signed-off-by: Haibo Xu <haibo.xu@linaro.org>
Signed-off-by: Miguel Luis <miguel.luis@oracle.com>
Signed-off-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20250707164129.1167837-4-eric.auger@redhat.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 target/arm/kvm.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/target/arm/kvm.c b/target/arm/kvm.c
index 9fdf354f3bc..66723448554 100644
--- a/target/arm/kvm.c
+++ b/target/arm/kvm.c
@@ -251,6 +251,7 @@ static bool kvm_arm_get_host_cpu_features(ARMHostCPUFeatures *ahcf)
      */
     int fdarray[3];
     bool sve_supported;
+    bool el2_supported;
     bool pmu_supported = false;
     uint64_t features = 0;
     int err;
@@ -270,6 +271,14 @@ static bool kvm_arm_get_host_cpu_features(ARMHostCPUFeatures *ahcf)
         init.features[0] |= 1 << KVM_ARM_VCPU_SVE;
     }
 
+    /*
+     * Ask for EL2 if supported.
+     */
+    el2_supported = kvm_arm_el2_supported();
+    if (el2_supported) {
+        init.features[0] |= 1 << KVM_ARM_VCPU_HAS_EL2;
+    }
+
     /*
      * Ask for Pointer Authentication if supported, so that we get
      * the unsanitized field values for AA64ISAR1_EL1.
@@ -423,6 +432,10 @@ static bool kvm_arm_get_host_cpu_features(ARMHostCPUFeatures *ahcf)
     features |= 1ULL << ARM_FEATURE_AARCH64;
     features |= 1ULL << ARM_FEATURE_GENERIC_TIMER;
 
+    if (el2_supported) {
+        features |= 1ULL << ARM_FEATURE_EL2;
+    }
+
     ahcf->features = features;
 
     return true;
@@ -1888,6 +1901,9 @@ int kvm_arch_init_vcpu(CPUState *cs)
         cpu->kvm_init_features[0] |= (1 << KVM_ARM_VCPU_PTRAUTH_ADDRESS |
                                       1 << KVM_ARM_VCPU_PTRAUTH_GENERIC);
     }
+    if (cpu->has_el2 && kvm_arm_el2_supported()) {
+        cpu->kvm_init_features[0] |= 1 << KVM_ARM_VCPU_HAS_EL2;
+    }
 
     /* Do KVM_ARM_VCPU_INIT ioctl */
     ret = kvm_arm_vcpu_init(cpu);
-- 
2.43.0