On Mon, Jan 28, 2019 at 06:35:34PM +0100, Cédric Le Goater wrote:

On 1/22/19 6:05 AM, Paul Mackerras wrote:

quoted

On Mon, Jan 07, 2019 at 07:43:17PM +0100, Cédric Le Goater wrote:

quoted

This is the basic framework for the new KVM device supporting the XIVE
native exploitation mode. The user interface exposes a new capability
and a new KVM device to be used by QEMU.

[snip]

quoted

@@ -1039,7 +1039,10 @@ static int kvmppc_book3s_init(void)
 #ifdef CONFIG_KVM_XIVE
 	if (xive_enabled()) {
 		kvmppc_xive_init_module();
+		kvmppc_xive_native_init_module();
 		kvm_register_device_ops(&kvm_xive_ops, KVM_DEV_TYPE_XICS);
+		kvm_register_device_ops(&kvm_xive_native_ops,
+					KVM_DEV_TYPE_XIVE);

I think we want tighter conditions on initializing the xive_native
stuff and creating the xive device class.  We could have
xive_enabled() returning true in a guest, and this code will get
called both by PR KVM and HV KVM (and HV KVM no longer implies that we
are running bare metal).

So yes, I gave nested a try with kernel_irqchip=on and the nested hypervisor 
(L1) obviously crashes trying to call OPAL. I have tighten the test with : 

	if (xive_enabled() && !kvmhv_on_pseries()) {

for now.

As this is a problem today in 5.0.x, I will send a patch for it if you think

How do you mean this is a problem today in 5.0?  I just tried 5.0-rc1
with kernel_irqchip=on in a nested guest and it works just fine.  What
exactly did you test?

it is correct. I don't think we should bother taking care of the PR case
on P9. Should we ? 

We do need to take care of PR KVM on P9, since it is the only form of
nested KVM that works inside a host in HPT mode.

Paul.