[Qemu-devel] [PATCH 3/3] spapr: Implement ibm,suspend-me

[Nicholas Piggin <npiggin@gmail.com>]

This has been useful to modify and test the Linux pseries suspend
code but it requires modification to the guest to call it (due to
being gated by other unimplemented features). It is not otherwise
used by Linux yet, but work is slowly progressing there.

This allows a (lightly modified) guest kernel to suspend with
`echo mem > /sys/power/state` and be resumed with system_wakeup
monitor command.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 hw/ppc/spapr.c         | 11 +++++++++++
 hw/ppc/spapr_rtas.c    | 32 ++++++++++++++++++++++++++++++++
 include/hw/ppc/spapr.h |  3 ++-
 3 files changed, 45 insertions(+), 1 deletion(-)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 00f7735a31..c7725d3586 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -1701,6 +1701,14 @@ static int spapr_reset_drcs(Object *child, void *opaque)
     return 0;
 }
 
+static void spapr_machine_wakeup(MachineState *machine)
+{
+    /*
+     * Nothing needs to be done to resume a suspended guest because
+     * suspending does not change the machine state.
+     */
+}
+
 static void spapr_machine_reset(MachineState *machine)
 {
     SpaprMachineState *spapr = SPAPR_MACHINE(machine);
@@ -3078,6 +3086,8 @@ static void spapr_machine_init(MachineState *machine)
 
     qemu_register_boot_set(spapr_boot_set, spapr);
 
+    qemu_register_wakeup_support();
+
     if (kvm_enabled()) {
         /* to stop and start vmclock */
         qemu_add_vm_change_state_handler(cpu_ppc_clock_vm_state_change,
@@ -4373,6 +4383,7 @@ static void spapr_machine_class_init(ObjectClass *oc, void *data)
      */
     mc->init = spapr_machine_init;
     mc->reset = spapr_machine_reset;
+    mc->wakeup = spapr_machine_wakeup;
     mc->block_default_type = IF_SCSI;
     mc->max_cpus = 1024;
     mc->no_parallel = 1;
diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c
index a618a2ac0f..87175c1e0a 100644
--- a/hw/ppc/spapr_rtas.c
+++ b/hw/ppc/spapr_rtas.c
@@ -216,6 +216,36 @@ static void rtas_stop_self(PowerPCCPU *cpu, SpaprMachineState *spapr,
     qemu_cpu_kick(cs);
 }
 
+static void rtas_ibm_suspend_me(PowerPCCPU *cpu, SpaprMachineState *spapr,
+                           uint32_t token, uint32_t nargs,
+                           target_ulong args,
+                           uint32_t nret, target_ulong rets)
+{
+    CPUState *cs;
+
+    if (nargs != 0 || nret != 1) {
+        rtas_st(rets, 0, RTAS_OUT_PARAM_ERROR);
+        return;
+    }
+
+    CPU_FOREACH(cs) {
+        PowerPCCPU *c = POWERPC_CPU(cs);
+        CPUPPCState *e = &c->env;
+        if (c == cpu) {
+            continue;
+        }
+
+        /* See h_join */
+        if (!cs->halted || (e->msr & (1ULL << MSR_EE))) {
+            rtas_st(rets, 0, H_MULTI_THREADS_ACTIVE);
+            return;
+        }
+    }
+
+    qemu_system_suspend_request();
+    rtas_st(rets, 0, RTAS_OUT_SUCCESS);
+}
+
 static inline int sysparm_st(target_ulong addr, target_ulong len,
                              const void *val, uint16_t vallen)
 {
@@ -483,6 +513,8 @@ static void core_rtas_register_types(void)
                         rtas_query_cpu_stopped_state);
     spapr_rtas_register(RTAS_START_CPU, "start-cpu", rtas_start_cpu);
     spapr_rtas_register(RTAS_STOP_SELF, "stop-self", rtas_stop_self);
+    spapr_rtas_register(RTAS_IBM_SUSPEND_ME, "ibm,suspend-me",
+                        rtas_ibm_suspend_me);
     spapr_rtas_register(RTAS_IBM_GET_SYSTEM_PARAMETER,
                         "ibm,get-system-parameter",
                         rtas_ibm_get_system_parameter);
diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index 5d36eec9d0..6e8e18b077 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -631,8 +631,9 @@ target_ulong spapr_hypercall(PowerPCCPU *cpu, target_ulong opcode,
 #define RTAS_IBM_CREATE_PE_DMA_WINDOW           (RTAS_TOKEN_BASE + 0x27)
 #define RTAS_IBM_REMOVE_PE_DMA_WINDOW           (RTAS_TOKEN_BASE + 0x28)
 #define RTAS_IBM_RESET_PE_DMA_WINDOW            (RTAS_TOKEN_BASE + 0x29)
+#define RTAS_IBM_SUSPEND_ME                     (RTAS_TOKEN_BASE + 0x2A)
 
-#define RTAS_TOKEN_MAX                          (RTAS_TOKEN_BASE + 0x2A)
+#define RTAS_TOKEN_MAX                          (RTAS_TOKEN_BASE + 0x2B)
 
 /* RTAS ibm,get-system-parameter token values */
 #define RTAS_SYSPARM_SPLPAR_CHARACTERISTICS      20
-- 
2.20.1