spapr: Add H-Call H_HOME_NODE_ASSOCIATIVITY

H_HOME_NODE_ASSOCIATIVITY H-Call returns the associativity domain
designation associated with the identifier input parameter

This fixes a crash when we try to hotplug a CPU in memory-less and
CPU-less numa node. In this case, the kernel tries to online the
node, but without the information provided by this h-call, the node id,
it cannot and the CPU is started while the node is not onlined.

It also removes the warning message from the kernel:
  VPHN is not supported. Disabling polling..

Signed-off-by: Laurent Vivier <lvivier@redhat.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

hw/ppc/spapr.c

@@ -1048,6 +1048,7 @@ static void spapr_dt_rtas(sPAPRMachineState *spapr, void *fdt)
     add_str(hypertas, "hcall-sprg0");
     add_str(hypertas, "hcall-copy");
     add_str(hypertas, "hcall-debug");
+    add_str(hypertas, "hcall-vphn");
     add_str(qemu_hypertas, "hcall-memop1");
 
     if (!kvm_enabled() || kvmppc_spapr_use_multitce()) {

hw/ppc/spapr_hcall.c

@@ -1663,6 +1663,42 @@ static target_ulong h_client_architecture_support(PowerPCCPU *cpu,
     return H_SUCCESS;
 }
 
+static target_ulong h_home_node_associativity(PowerPCCPU *cpu,
+                                              sPAPRMachineState *spapr,
+                                              target_ulong opcode,
+                                              target_ulong *args)
+{
+    target_ulong flags = args[0];
+    target_ulong procno = args[1];
+    PowerPCCPU *tcpu;
+    int idx;
+
+    /* only support procno from H_REGISTER_VPA */
+    if (flags != 0x1) {
+        return H_FUNCTION;
+    }
+
+    tcpu = spapr_find_cpu(procno);
+    if (tcpu == NULL) {
+        return H_P2;
+    }
+
+    /* sequence is the same as in the "ibm,associativity" property */
+
+    idx = 0;
+#define ASSOCIATIVITY(a, b) (((uint64_t)(a) << 32) | \
+                             ((uint64_t)(b) & 0xffffffff))
+    args[idx++] = ASSOCIATIVITY(0, 0);
+    args[idx++] = ASSOCIATIVITY(0, tcpu->node_id);
+    args[idx++] = ASSOCIATIVITY(procno, -1);
+    for ( ; idx < 6; idx++) {
+        args[idx] = -1;
+    }
+#undef ASSOCIATIVITY
+
+    return H_SUCCESS;
+}
+
 static target_ulong h_get_cpu_characteristics(PowerPCCPU *cpu,
                                               sPAPRMachineState *spapr,
                                               target_ulong opcode,
@@ -1822,6 +1858,10 @@ static void hypercall_register_types(void)
 
     /* ibm,client-architecture-support support */
     spapr_register_hypercall(KVMPPC_H_CAS, h_client_architecture_support);
+
+    /* Virtual Processor Home Node */
+    spapr_register_hypercall(H_HOME_NODE_ASSOCIATIVITY,
+                             h_home_node_associativity);
 }
 
 type_init(hypercall_register_types)

include/hw/ppc/spapr.h

@@ -444,6 +444,7 @@ struct sPAPRMachineState {
 #define H_GET_EM_PARMS          0x2B8
 #define H_SET_MPP               0x2D0
 #define H_GET_MPP               0x2D4
+#define H_HOME_NODE_ASSOCIATIVITY 0x2EC
 #define H_XIRR_X                0x2FC
 #define H_RANDOM                0x300
 #define H_SET_MODE              0x31C