[PATCH 03/23] KVM: PPC: Book3S HV: Nested: Don't allow hash guests to run nested guests

[Suraj Jitindar Singh <sjitindarsingh@gmail.com>]

Don't allow hpt (hash page table) guests to act as guest hypervisors and
thus be able to run nested guests. There is currently no support for
this, if a nested guest is to be run it must be run at the lowest level.
Explicitly disallow hash guests from enabling the nested kvm-hv capability
at the hypervisor level.

Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
---
 arch/powerpc/kvm/book3s_hv.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index cde3f5a4b3e4..ce960301bfaa 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -5336,8 +5336,12 @@ static int kvmhv_enable_nested(struct kvm *kvm)
 		return -ENODEV;
 
 	/* kvm == NULL means the caller is testing if the capability exists */
-	if (kvm)
+	if (kvm) {
+		/* Only radix guests can act as nested hv and thus run guests */
+		if (!kvm_is_radix(kvm))
+			return -1;
 		kvm->arch.nested_enable = true;
+	}
 	return 0;
 }
 
-- 
2.13.6