[v3,09/19] ppc: Add has_smt_siblings property to CPUPPCState

Commit Message

Nicholas Piggin July 16, 2024, 4:26 p.m. UTC

The decision to branch out to a slower SMT path in instruction
emulation will become a bit more complicated with the way that
"big-core" topology that will be implemented in subsequent changes.
Hide these details from the wider CPU emulation code with a bool
has_smt_siblings flag that can be set by machine initialisation.

Reviewed-by: Cédric Le Goater <[e-mail]>
Signed-off-by: Nicholas Piggin <[e-mail]>
---
 target/ppc/cpu.h        |  3 ++-
 hw/ppc/pnv_core.c       |  3 +++
 hw/ppc/spapr_cpu_core.c | 12 +++++++++---
 3 files changed, 14 insertions(+), 4 deletions(-)

Patch

diff --git a/target/ppc/cpu.h b/target/ppc/cpu.h
index 417b284318..321ed2da75 100644
--- a/target/ppc/cpu.h
+++ b/target/ppc/cpu.h
@@ -1248,6 +1248,7 @@  struct CPUArchState {
     int access_type;
 
     /* For SMT processors */
+    bool has_smt_siblings;
     int core_index;
 
 #if !defined(CONFIG_USER_ONLY)
@@ -1514,7 +1515,7 @@  struct PowerPCCPUClass {
 
 static inline bool ppc_cpu_core_single_threaded(CPUState *cs)
 {
-    return cs->nr_threads == 1;
+    return !POWERPC_CPU(cs)->env.has_smt_siblings;
 }
 
 static inline bool ppc_cpu_lpar_single_threaded(CPUState *cs)
diff --git a/hw/ppc/pnv_core.c b/hw/ppc/pnv_core.c
index 7bda29b9c7..8cfa94fbfa 100644
--- a/hw/ppc/pnv_core.c
+++ b/hw/ppc/pnv_core.c
@@ -288,6 +288,9 @@  static void pnv_core_realize(DeviceState *dev, Error **errp)
         cpu = POWERPC_CPU(obj);
 
         pc->threads[i] = POWERPC_CPU(obj);
+        if (cc->nr_threads > 1) {
+            cpu->env.has_smt_siblings = true;
+        }
 
         snprintf(name, sizeof(name), "thread[%d]", i);
         object_property_add_child(OBJECT(pc), name, obj);
diff --git a/hw/ppc/spapr_cpu_core.c b/hw/ppc/spapr_cpu_core.c
index 4e13e6993a..2c6eeb41a4 100644
--- a/hw/ppc/spapr_cpu_core.c
+++ b/hw/ppc/spapr_cpu_core.c
@@ -351,9 +351,15 @@  static void spapr_cpu_core_realize(DeviceState *dev, Error **errp)
     qemu_register_reset(spapr_cpu_core_reset_handler, sc);
     sc->threads = g_new0(PowerPCCPU *, cc->nr_threads);
     for (i = 0; i < cc->nr_threads; i++) {
-        sc->threads[i] = spapr_create_vcpu(sc, i, errp);
-        if (!sc->threads[i] ||
-            !spapr_realize_vcpu(sc->threads[i], spapr, sc, i, errp)) {
+        PowerPCCPU *cpu;
+
+        cpu = spapr_create_vcpu(sc, i, errp);
+        sc->threads[i] = cpu;
+        if (cpu && cc->nr_threads > 1) {
+            cpu->env.has_smt_siblings = true;
+        }
+
+        if (!cpu || !spapr_realize_vcpu(cpu, spapr, sc, i, errp)) {
             spapr_cpu_core_unrealize(dev);
             return;
         }