KVM: PPC: Book3S HV: Don't do ultravisor calls on systems without ultravisor

Commit 22945688acd4 ("KVM: PPC: Book3S HV: Support reset of secure
guest") added a call to uv_svm_terminate, which is an ultravisor
call, without any check that the guest is a secure guest or even that
the system has an ultravisor.  On a system without an ultravisor,
the ultracall will degenerate to a hypercall, but since we are not
in KVM guest context, the hypercall will get treated as a system
call, which could have random effects depending on what happens to
be in r0, and could also corrupt the current task's kernel stack.
Hence this adds a test for the guest being a secure guest before
doing uv_svm_terminate().

Fixes: 22945688acd4 ("KVM: PPC: Book3S HV: Support reset of secure guest")
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>

diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index dc53578..6ff3f89 100644 (file)
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -4983,7 +4983,8 @@ static void kvmppc_core_destroy_vm_hv(struct kvm *kvm)
                if (nesting_enabled(kvm))
                        kvmhv_release_all_nested(kvm);
                kvm->arch.process_table = 0;
-               uv_svm_terminate(kvm->arch.lpid);
+               if (kvm->arch.secure_guest)
+                       uv_svm_terminate(kvm->arch.lpid);
                kvmhv_set_ptbl_entry(kvm->arch.lpid, 0, 0);
        }