target/ppc: fix icount support on Book-e vms accessing SPRs

Failing to guard SPR access with gen_io_start/gen_stop_exception
causes "Bad icount read" exceptions when running VMs with
e500mc and e500v2 CPUs with an icount parameter.

Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: Greg Kurz <groug@kaod.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Vitaly Cheptsov <cheptsov@ispras.ru>
Message-Id: <20210303140851.78383-1-cheptsov@ispras.ru>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

target/ppc/translate_init.c.inc

@@ -567,35 +567,71 @@ static void spr_write_601_ubatl(DisasContext *ctx, int sprn, int gprn)
 #if !defined(CONFIG_USER_ONLY)
 static void spr_read_40x_pit(DisasContext *ctx, int gprn, int sprn)
 {
+    if (tb_cflags(ctx->base.tb) & CF_USE_ICOUNT) {
+        gen_io_start();
+    }
     gen_helper_load_40x_pit(cpu_gpr[gprn], cpu_env);
+    if (tb_cflags(ctx->base.tb) & CF_USE_ICOUNT) {
+        gen_stop_exception(ctx);
+    }
 }
 
 static void spr_write_40x_pit(DisasContext *ctx, int sprn, int gprn)
 {
+    if (tb_cflags(ctx->base.tb) & CF_USE_ICOUNT) {
+        gen_io_start();
+    }
     gen_helper_store_40x_pit(cpu_env, cpu_gpr[gprn]);
+    if (tb_cflags(ctx->base.tb) & CF_USE_ICOUNT) {
+        gen_stop_exception(ctx);
+    }
 }
 
 static void spr_write_40x_dbcr0(DisasContext *ctx, int sprn, int gprn)
 {
+    if (tb_cflags(ctx->base.tb) & CF_USE_ICOUNT) {
+        gen_io_start();
+    }
     gen_store_spr(sprn, cpu_gpr[gprn]);
     gen_helper_store_40x_dbcr0(cpu_env, cpu_gpr[gprn]);
     /* We must stop translation as we may have rebooted */
     gen_stop_exception(ctx);
+    if (tb_cflags(ctx->base.tb) & CF_USE_ICOUNT) {
+        gen_stop_exception(ctx);
+    }
 }
 
 static void spr_write_40x_sler(DisasContext *ctx, int sprn, int gprn)
 {
+    if (tb_cflags(ctx->base.tb) & CF_USE_ICOUNT) {
+        gen_io_start();
+    }
     gen_helper_store_40x_sler(cpu_env, cpu_gpr[gprn]);
+    if (tb_cflags(ctx->base.tb) & CF_USE_ICOUNT) {
+        gen_stop_exception(ctx);
+    }
 }
 
 static void spr_write_booke_tcr(DisasContext *ctx, int sprn, int gprn)
 {
+    if (tb_cflags(ctx->base.tb) & CF_USE_ICOUNT) {
+        gen_io_start();
+    }
     gen_helper_store_booke_tcr(cpu_env, cpu_gpr[gprn]);
+    if (tb_cflags(ctx->base.tb) & CF_USE_ICOUNT) {
+        gen_stop_exception(ctx);
+    }
 }
 
 static void spr_write_booke_tsr(DisasContext *ctx, int sprn, int gprn)
 {
+    if (tb_cflags(ctx->base.tb) & CF_USE_ICOUNT) {
+        gen_io_start();
+    }
     gen_helper_store_booke_tsr(cpu_env, cpu_gpr[gprn]);
+    if (tb_cflags(ctx->base.tb) & CF_USE_ICOUNT) {
+        gen_stop_exception(ctx);
+    }
 }
 #endif