spapr: nested: register nested-hv api hcalls only for cap-nested-hv

Since cap-nested-hv is an optional capability, it makes sense to register
api specfic hcalls only when respective capability is enabled. This
requires to introduce a new API to unregister hypercalls to maintain
sanity across guest reboot since caps are re-applied across reboots and
re-registeration of hypercalls would hit assert otherwise.

Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>

1 files changed, 22 insertions, 2 deletions

diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c
index 75c2d12978..5e1d020e3d 100644
--- a/hw/ppc/spapr_hcall.c
+++ b/hw/ppc/spapr_hcall.c
@@ -1525,6 +1525,28 @@ void spapr_register_hypercall(target_ulong opcode, spapr_hcall_fn fn)
     *slot = fn;
 }
 
+void spapr_unregister_hypercall(target_ulong opcode)
+{
+    spapr_hcall_fn *slot;
+
+    if (opcode <= MAX_HCALL_OPCODE) {
+        assert((opcode & 0x3) == 0);
+
+        slot = &papr_hypercall_table[opcode / 4];
+    } else if (opcode >= SVM_HCALL_BASE && opcode <= SVM_HCALL_MAX) {
+        /* we only have SVM-related hcall numbers assigned in multiples of 4 */
+        assert((opcode & 0x3) == 0);
+
+        slot = &svm_hypercall_table[(opcode - SVM_HCALL_BASE) / 4];
+    } else {
+        assert((opcode >= KVMPPC_HCALL_BASE) && (opcode <= KVMPPC_HCALL_MAX));
+
+        slot = &kvmppc_hypercall_table[opcode - KVMPPC_HCALL_BASE];
+    }
+
+    *slot = NULL;
+}
+
 target_ulong spapr_hypercall(PowerPCCPU *cpu, target_ulong opcode,
                              target_ulong *args)
 {
@@ -1638,8 +1660,6 @@ static void hypercall_register_types(void)
     spapr_register_hypercall(KVMPPC_H_CAS, h_client_architecture_support);
 
     spapr_register_hypercall(KVMPPC_H_UPDATE_DT, h_update_dt);
-
-    spapr_register_nested();
 }
 
 type_init(hypercall_register_types)