arch-arm: Improve error message when KVM failed to be initialized

Change-Id: If7f87cbd6c4e01134b17875e7c69f6147a5ed1f6
Signed-off-by: Hoa Nguyen <hoanguyen@ucdavis.edu>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/60312
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Bobby Bruce <bbruce@ucdavis.edu>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Bobby Bruce <bbruce@ucdavis.edu>

src/arch/arm/kvm/base_cpu.cc

@@ -220,7 +220,8 @@ void
 BaseArmKvmCPU::kvmArmVCpuInit(const struct kvm_vcpu_init &init)
 {
     if (ioctl(KVM_ARM_VCPU_INIT, (void *)&init) == -1)
-        panic("KVM: Failed to initialize vCPU\n");
+        panic("KVM: Failed to initialize vCPU; errno %d (%s)\n",
+            errno, strerror(errno));
 }
 
 bool