[v5,1/9] i386/cpu: Don't enumerate the "invalid" CPU topology level

Commit Message

Zhao Liu Nov. 1, 2024, 8:33 a.m. UTC

In the follow-up change, the CPU topology enumeration will be moved to
QAPI. And considerring "invalid" should not be exposed to QAPI as an
unsettable item, so, as a preparation for future changes, remove
"invalid" level from the current CPU topology enumeration structure
and define it by a macro instead.

Due to the removal of the enumeration of "invalid", bit 0 of
CPUX86State.avail_cpu_topo bitmap will no longer correspond to "invalid"
level, but will start at the SMT level. Therefore, to honor this change,
update the encoding rule for CPUID[0x1F].

Signed-off-by: Zhao Liu <[e-mail]>
Reviewed-by: Jonathan Cameron <[e-mail]>
---
Tested by the following cases to ensure 0x1f's behavior hasn't
changed:
  -smp cpus=24,sockets=2,dies=3,modules=2,cores=2,threads=1
  -smp cpus=24,sockets=2,dies=1,modules=3,cores=2,threads=2
  -smp cpus=24,sockets=2,modules=3,cores=2,threads=2
  -smp cpus=24,sockets=2,dies=3,modules=1,cores=2,threads=2
  -smp cpus=24,sockets=2,dies=3,cores=2,threads=2
---
Changes since Patch v3:
  * Now commit to stop exposing "invalid" enumeration in QAPI. (Daniel)
---
 include/hw/i386/topology.h |  3 ++-
 target/i386/cpu.c          | 13 ++++++++-----
 2 files changed, 10 insertions(+), 6 deletions(-)

Patch

diff --git a/include/hw/i386/topology.h b/include/hw/i386/topology.h
index dff49fce1154..48b43edc5a90 100644
--- a/include/hw/i386/topology.h
+++ b/include/hw/i386/topology.h
@@ -62,6 +62,8 @@  typedef struct X86CPUTopoInfo {
     unsigned threads_per_core;
 } X86CPUTopoInfo;
 
+#define CPU_TOPO_LEVEL_INVALID CPU_TOPO_LEVEL_MAX
+
 /*
  * CPUTopoLevel is the general i386 topology hierarchical representation,
  * ordered by increasing hierarchical relationship.
@@ -69,7 +71,6 @@  typedef struct X86CPUTopoInfo {
  * or AMD (CPUID[0x80000026]).
  */
 enum CPUTopoLevel {
-    CPU_TOPO_LEVEL_INVALID,
     CPU_TOPO_LEVEL_SMT,
     CPU_TOPO_LEVEL_CORE,
     CPU_TOPO_LEVEL_MODULE,
diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 3baa95481fbc..ca13cf66a787 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -370,20 +370,21 @@  static void encode_topo_cpuid1f(CPUX86State *env, uint32_t count,
                                 uint32_t *ecx, uint32_t *edx)
 {
     X86CPU *cpu = env_archcpu(env);
-    unsigned long level, next_level;
+    unsigned long level, base_level, next_level;
     uint32_t num_threads_next_level, offset_next_level;
 
-    assert(count + 1 < CPU_TOPO_LEVEL_MAX);
+    assert(count <= CPU_TOPO_LEVEL_PACKAGE);
 
     /*
      * Find the No.(count + 1) topology level in avail_cpu_topo bitmap.
-     * The search starts from bit 1 (CPU_TOPO_LEVEL_INVALID + 1).
+     * The search starts from bit 0 (CPU_TOPO_LEVEL_SMT).
      */
-    level = CPU_TOPO_LEVEL_INVALID;
+    level = CPU_TOPO_LEVEL_SMT;
+    base_level = level;
     for (int i = 0; i <= count; i++) {
         level = find_next_bit(env->avail_cpu_topo,
                               CPU_TOPO_LEVEL_PACKAGE,
-                              level + 1);
+                              base_level);
 
         /*
          * CPUID[0x1f] doesn't explicitly encode the package level,
@@ -394,6 +395,8 @@  static void encode_topo_cpuid1f(CPUX86State *env, uint32_t count,
             level = CPU_TOPO_LEVEL_INVALID;
             break;
         }
+        /* Search the next level. */
+        base_level = level + 1;
     }
 
     if (level == CPU_TOPO_LEVEL_INVALID) {