@@ -1070,6 +1070,72 @@ static target_ulong h_cede(PowerPCCPU *cpu, SpaprMachineState *spapr,
return H_SUCCESS;
}
+static target_ulong h_confer(PowerPCCPU *cpu, SpaprMachineState *spapr,
+ target_ulong opcode, target_ulong *args)
+{
+ target_long target = args[0];
+ uint32_t dispatch = args[1];
+ CPUState *cs = CPU(cpu);
+ SpaprCpuState *spapr_cpu;
+
+ /*
+ * -1 means confer to all other CPUs without dispatch counter check,
+ * otherwise it's a targeted confer.
+ */
+ if (target != -1) {
+ PowerPCCPU *target_cpu = spapr_find_cpu(target);
+ uint32_t target_dispatch;
+
+ if (!target_cpu) {
+ return H_PARAMETER;
+ }
+
+ spapr_cpu = spapr_cpu_state(target_cpu);
+
+ /*
+ * target == self is a special case, we wait until prodded, without
+ * dispatch counter check.
+ */
+ if (cpu == target_cpu) {
+ if (spapr_cpu->prod) {
+ spapr_cpu->prod = false;
+
+ return H_SUCCESS;
+ }
+
+ cs->halted = 1;
+ cs->exception_index = EXCP_HALTED;
+ cs->exit_request = 1;
+
+ return H_SUCCESS;
+ }
+
+ if (!spapr_cpu->vpa_addr || ((dispatch & 1) == 0)) {
+ return H_SUCCESS;
+ }
+
+ target_dispatch = ldl_be_phys(cs->as,
+ spapr_cpu->vpa_addr + VPA_DISPATCH_COUNTER);
+ if (target_dispatch != dispatch) {
+ return H_SUCCESS;
+ }
+
+ /*
+ * The targeted confer does not do anything special beyond yielding
+ * the current vCPU, but even this should be better than nothing.
+ * At least for single-threaded tcg, it gives the target a chance to
+ * run before we run again. Multi-threaded tcg does not really do
+ * anything with EXCP_YIELD yet.
+ */
+ }
+
+ cs->exception_index = EXCP_YIELD;
+ cs->exit_request = 1;
+ cpu_loop_exit(cs);
+
+ return H_SUCCESS;
+}
+
static target_ulong h_prod(PowerPCCPU *cpu, SpaprMachineState *spapr,
target_ulong opcode, target_ulong *args)
{
@@ -1915,6 +1981,7 @@ static void hypercall_register_types(void)
/* hcall-splpar */
spapr_register_hypercall(H_REGISTER_VPA, h_register_vpa);
spapr_register_hypercall(H_CEDE, h_cede);
+ spapr_register_hypercall(H_CONFER, h_confer);
spapr_register_hypercall(H_PROD, h_prod);
spapr_register_hypercall(H_SIGNAL_SYS_RESET, h_signal_sys_reset);