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charset="us-ascii" On Wed, Jun 10, 2026, Ritesh Harjani (IBM) wrote: > Print the vcpu_id and errno when the KVM_CREATE_VCPU ioctl fails, for > debug purposes. > This helped in debugging an issue with KVM on PowerVM, where KVM_CREATE_VCPU > only supports max 2048 vcpus, because the PAPR_HCALL H_GUEST_CREATE_VCPU > ("Documentation/arch/powerpc/kvm-nested.rst") supports only up to 0-2047 > vcpu_id. However KVM_CAP_MAX_VCPUS capability extension always reports max_vcpus > as NR_CPUS of the host. > > Signed-off-by: Ritesh Harjani (IBM) > --- > tools/testing/selftests/kvm/lib/kvm_util.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c > index e00a25f59416..6319e2037882 100644 > --- a/tools/testing/selftests/kvm/lib/kvm_util.c > +++ b/tools/testing/selftests/kvm/lib/kvm_util.c > @@ -1354,6 +1354,13 @@ struct kvm_vcpu *__vm_vcpu_add(struct kvm_vm *vm, u32 vcpu_id) > vcpu->vm = vm; > vcpu->id = vcpu_id; > vcpu->fd = __vm_ioctl(vm, KVM_CREATE_VCPU, (void *)(unsigned long)vcpu_id); > + if (vcpu->fd < 0) { > + int saved_errno = errno; > + > + pr_info("Failed KVM_CREATE_VCPU for vcpu_id %u with errno %d\n", > + vcpu_id, saved_errno); > + errno = saved_errno; Sorry, but NAK. There are myriad failures where printing extra information can help debug a failure/assert, I don't want to create a slippery slope where the codebase is littered with extra print statements that someone found useful at some point.