[Qemu-devel] [RFC 1/3] using CPUMASK bitmaps to calculate cpu index

[Chen Fan]

instead of seeking the number of CPUs, using CPUMASK bitmaps to
calculate the cpu index, also would be a gread benefit to remove
cpu index.

Signed-off-by: Chen Fan <chen.fan.f...@cn.fujitsu.com>
---
 exec.c                  | 9 ++++-----
 include/qom/cpu.h       | 9 +++++++++
 include/sysemu/sysemu.h | 7 -------
 3 files changed, 13 insertions(+), 12 deletions(-)

diff --git a/exec.c b/exec.c
index cf12049..2948841 100644
--- a/exec.c
+++ b/exec.c
@@ -473,16 +473,15 @@ void cpu_exec_init(CPUArchState *env)
 {
     CPUState *cpu = ENV_GET_CPU(env);
     CPUClass *cc = CPU_GET_CLASS(cpu);
-    CPUState *some_cpu;
     int cpu_index;
 
 #if defined(CONFIG_USER_ONLY)
     cpu_list_lock();
 #endif
-    cpu_index = 0;
-    CPU_FOREACH(some_cpu) {
-        cpu_index++;
-    }
+    cpu_index = find_first_zero_bit(cc->cpu_present_mask,
+                                    MAX_CPUMASK_BITS);
+    set_bit(cpu_index, cc->cpu_present_mask);
+
     cpu->cpu_index = cpu_index;
     cpu->numa_node = 0;
     QTAILQ_INIT(&cpu->breakpoints);
diff --git a/include/qom/cpu.h b/include/qom/cpu.h
index df977c8..b8f46b1 100644
--- a/include/qom/cpu.h
+++ b/include/qom/cpu.h
@@ -70,6 +70,13 @@ typedef void (*CPUUnassignedAccess)(CPUState *cpu, hwaddr 
addr,
 
 struct TranslationBlock;
 
+/* The following shall be true for all CPUs:
+ *   cpu->cpu_index < max_cpus <= MAX_CPUMASK_BITS
+ *
+ * Note that cpu->get_arch_id() may be larger than MAX_CPUMASK_BITS.
+ */
+#define MAX_CPUMASK_BITS 255
+
 /**
  * CPUClass:
  * @class_by_name: Callback to map -cpu command line model name to an
@@ -142,6 +149,8 @@ typedef struct CPUClass {
     const struct VMStateDescription *vmsd;
     int gdb_num_core_regs;
     const char *gdb_core_xml_file;
+
+    DECLARE_BITMAP(cpu_present_mask, MAX_CPUMASK_BITS);
 } CPUClass;
 
 #ifdef HOST_WORDS_BIGENDIAN
diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
index ba5c7f8..04edb8b 100644
--- a/include/sysemu/sysemu.h
+++ b/include/sysemu/sysemu.h
@@ -134,13 +134,6 @@ extern QEMUClockType rtc_clock;
 
 #define MAX_NODES 64
 
-/* The following shall be true for all CPUs:
- *   cpu->cpu_index < max_cpus <= MAX_CPUMASK_BITS
- *
- * Note that cpu->get_arch_id() may be larger than MAX_CPUMASK_BITS.
- */
-#define MAX_CPUMASK_BITS 255
-
 extern int nb_numa_nodes;
 extern uint64_t node_mem[MAX_NODES];
 extern unsigned long *node_cpumask[MAX_NODES];
-- 
1.8.1.4