target/ppc: Add initial flags and helpers for SMT support

TGC SMT emulation needs to know whether it is running with SMT siblings, to be able to iterate over siblings in a core, and to serialise threads to access per-core shared SPRs. Add infrastructure to do these things. For now the sibling iteration and serialisation are implemented in a simple but inefficient way. SMT shared state and sibling access is not too common, and SMT configurations are mainly useful to test system code, so performance is not to critical. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Reviewed-by: Cédric Le Goater <clg@kaod.org> [ clg: fix build breakage with clang ] Signed-off-by: Cédric Le Goater <clg@kaod.org>
qemu · Jun 25, 2023 · b769d4c · b769d4c
1 parent 984eda5
commit b769d4c
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diff --git a/target/ppc/cpu.h b/target/ppc/cpu.h
@@ -672,6 +672,8 @@ enum {
     POWERPC_FLAG_TM       = 0x00100000,
     /* Has SCV (ISA 3.00)                                                    */
     POWERPC_FLAG_SCV      = 0x00200000,
+    /* Has >1 thread per core                                                */
+    POWERPC_FLAG_SMT      = 0x00400000,
 };
 
 /*
@@ -1268,6 +1270,13 @@ struct CPUArchState {
     uint64_t pmu_base_time;
 };
 
+#define _CORE_ID(cs)                                            \
+    (POWERPC_CPU(cs)->env.spr_cb[SPR_PIR].default_value & ~(cs->nr_threads - 1))
+
+#define THREAD_SIBLING_FOREACH(cs, cs_sibling)                  \
+    CPU_FOREACH(cs_sibling)                                     \
+        if (_CORE_ID(cs) == _CORE_ID(cs_sibling))
+
 #define SET_FIT_PERIOD(a_, b_, c_, d_)          \
 do {                                            \
     env->fit_period[0] = (a_);                  \

diff --git a/target/ppc/cpu_init.c b/target/ppc/cpu_init.c
@@ -6755,6 +6755,7 @@ static void ppc_cpu_realize(DeviceState *dev, Error **errp)
 {
     CPUState *cs = CPU(dev);
     PowerPCCPU *cpu = POWERPC_CPU(dev);
+    CPUPPCState *env = &cpu->env;
     PowerPCCPUClass *pcc = POWERPC_CPU_GET_CLASS(cpu);
     Error *local_err = NULL;
 
@@ -6786,6 +6787,10 @@ static void ppc_cpu_realize(DeviceState *dev, Error **errp)
 
     pcc->parent_realize(dev, errp);
 
+    if (env_cpu(env)->nr_threads > 1) {
+        env->flags |= POWERPC_FLAG_SMT;
+    }
+
     return;
 
 unrealize:

diff --git a/target/ppc/translate.c b/target/ppc/translate.c
@@ -234,6 +234,28 @@ struct opc_handler_t {
     void (*handler)(DisasContext *ctx);
 };
 
+static inline bool gen_serialize(DisasContext *ctx)
+{
+    if (tb_cflags(ctx->base.tb) & CF_PARALLEL) {
+        /* Restart with exclusive lock.  */
+        gen_helper_exit_atomic(cpu_env);
+        ctx->base.is_jmp = DISAS_NORETURN;
+        return false;
+    }
+    return true;
+}
+
+#if defined(TARGET_PPC64) && !defined(CONFIG_USER_ONLY)
+static inline bool gen_serialize_core(DisasContext *ctx)
+{
+    if (ctx->flags & POWERPC_FLAG_SMT) {
+        return gen_serialize(ctx);
+    }
+
+    return true;
+}
+#endif
+
 /* SPR load/store helpers */
 static inline void gen_load_spr(TCGv t, int reg)
 {