On 7/10/26 8:46 PM, Lorenzo Pieralisi wrote:
On Fri, Jul 10, 2026 at 11:09:43AM +1000, Gavin Shan wrote:
[...]
After syncing the definitions with those in (v14) host series, I'm able to boot
a simple realm guest (no virtio devices) with one warning.
qemu-system-aarch64: Failed to enable KVM_CAP_ARM_NISV_TO_USER cap
That's because we need to use the VM instance specific check extension
rather than the global one before trying to enable the cap.
It is harmless.
Yes, the capability KVM_CAP_ARM_NISV_TO_USER has been hidden from realm guest
in the (v14) host series. With the following changes applied on the top, the
warning is avoided, I think the changes need to be integrated to [RFC v1 08/25]
target/arm/kvm: Use kvm_vm_check_extension() where necessary.
diff --git a/target/arm/kvm.c b/target/arm/kvm.c
index 3d5e16a21c..4c52ee7e1b 100644
--- a/target/arm/kvm.c
+++ b/target/arm/kvm.c
@@ -623,7 +623,7 @@ int kvm_arch_init(MachineState *ms, KVMState *s)
return -EINVAL;
}
- if (kvm_check_extension(s, KVM_CAP_ARM_NISV_TO_USER)) {
+ if (kvm_vm_check_extension(s, KVM_CAP_ARM_NISV_TO_USER)) {
if (kvm_vm_enable_cap(s, KVM_CAP_ARM_NISV_TO_USER, 0)) {
error_report("Failed to enable KVM_CAP_ARM_NISV_TO_USER cap");
} else {
Besides, I think it's known issue that 'reboot' doesn't work.
Welcome to Buildroot
buildroot login: root
root@guest:~# reboot
:
qemu-system-aarch64: cpus are not resettable, terminating
Thanks,
Gavin
Lorenzo
