spapr: Implement H_PROD

H_PROD is added, and H_CEDE is modified to test the prod bit
according to PAPR.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Message-Id: <20190718034214.14948-3-npiggin@gmail.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

hw/ppc/spapr.c

@@ -4312,6 +4312,7 @@ static void spapr_cpu_exec_enter(PPCVirtualHypervisor *vhyp, PowerPCCPU *cpu)
 
     /* These are only called by TCG, KVM maintains dispatch state */
 
+    spapr_cpu->prod = false;
     if (spapr_cpu->vpa_addr) {
         CPUState *cs = CPU(cpu);
         uint32_t dispatch;

hw/ppc/spapr_hcall.c

@@ -1051,14 +1051,44 @@ static target_ulong h_cede(PowerPCCPU *cpu, SpaprMachineState *spapr,
 {
     CPUPPCState *env = &cpu->env;
     CPUState *cs = CPU(cpu);
+    SpaprCpuState *spapr_cpu = spapr_cpu_state(cpu);
 
     env->msr |= (1ULL << MSR_EE);
     hreg_compute_hflags(env);
+
+    if (spapr_cpu->prod) {
+        spapr_cpu->prod = false;
+        return H_SUCCESS;
+    }
+
     if (!cpu_has_work(cs)) {
         cs->halted = 1;
         cs->exception_index = EXCP_HLT;
         cs->exit_request = 1;
     }
+
+    return H_SUCCESS;
+}
+
+static target_ulong h_prod(PowerPCCPU *cpu, SpaprMachineState *spapr,
+                           target_ulong opcode, target_ulong *args)
+{
+    target_long target = args[0];
+    PowerPCCPU *tcpu;
+    CPUState *cs;
+    SpaprCpuState *spapr_cpu;
+
+    tcpu = spapr_find_cpu(target);
+    cs = CPU(tcpu);
+    if (!cs) {
+        return H_PARAMETER;
+    }
+
+    spapr_cpu = spapr_cpu_state(tcpu);
+    spapr_cpu->prod = true;
+    cs->halted = 0;
+    qemu_cpu_kick(cs);
+
     return H_SUCCESS;
 }
 
@@ -1885,6 +1915,8 @@ 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_PROD, h_prod);
+
     spapr_register_hypercall(H_SIGNAL_SYS_RESET, h_signal_sys_reset);
 
     /* processor register resource access h-calls */

include/hw/ppc/spapr_cpu_core.h

@@ -46,6 +46,7 @@ typedef struct SpaprCpuState {
     uint64_t vpa_addr;
     uint64_t slb_shadow_addr, slb_shadow_size;
     uint64_t dtl_addr, dtl_size;
+    bool prod; /* not migrated, only used to improve dispatch latencies */
     struct ICPState *icp;
     struct XiveTCTX *tctx;
 } SpaprCpuState;