[v6,4/4] i386/cpu: add has_caches flag to check smp_cache configuration

Commit Message

Zhao Liu Dec. 19, 2024, 8:32 a.m. UTC

From: Alireza Sanaee <[e-mail]>

Add has_caches flag to SMPCompatProps, which helps in avoiding
extra checks for every single layer of caches in x86 (and ARM in
future).

Signed-off-by: Alireza Sanaee <[e-mail]>
Signed-off-by: Zhao Liu <[e-mail]>
Reviewed-by: Jonathan Cameron <[e-mail]>
---
Note: Picked from Alireza's series with the changes:
 * Moved the flag to SMPCompatProps with a new name "has_caches".
   This way, it remains consistent with the function and style of
   "has_clusters" in SMPCompatProps.
 * Dropped my previous TODO with the new flag.
---
Changes since Patch v2:
 * Picked a new patch frome Alireza's ARM smp-cache series.
---
 hw/core/machine-smp.c |  2 ++
 include/hw/boards.h   |  3 +++
 target/i386/cpu.c     | 11 +++++------
 3 files changed, 10 insertions(+), 6 deletions(-)

Patch

diff --git a/hw/core/machine-smp.c b/hw/core/machine-smp.c
index b954eb849027..fe66961341fe 100644
--- a/hw/core/machine-smp.c
+++ b/hw/core/machine-smp.c
@@ -325,6 +325,8 @@  bool machine_parse_smp_cache(MachineState *ms,
             return false;
         }
     }
+
+    mc->smp_props.has_caches = true;
     return true;
 }
 
diff --git a/include/hw/boards.h b/include/hw/boards.h
index 5723ee76bdea..c647e507d1a9 100644
--- a/include/hw/boards.h
+++ b/include/hw/boards.h
@@ -156,6 +156,8 @@  typedef struct {
  * @modules_supported - whether modules are supported by the machine
  * @cache_supported - whether cache (l1d, l1i, l2 and l3) configuration are
  *                    supported by the machine
+ * @has_caches - whether cache properties are explicitly specified in the
+ *               user provided smp-cache configuration
  */
 typedef struct {
     bool prefer_sockets;
@@ -166,6 +168,7 @@  typedef struct {
     bool drawers_supported;
     bool modules_supported;
     bool cache_supported[CACHE_LEVEL_AND_TYPE__MAX];
+    bool has_caches;
 } SMPCompatProps;
 
 /**
diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index bd5620dcc086..a9700fba991f 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -8039,13 +8039,12 @@  static void x86_cpu_realizefn(DeviceState *dev, Error **errp)
 
 #ifndef CONFIG_USER_ONLY
     MachineState *ms = MACHINE(qdev_get_machine());
+    MachineClass *mc = MACHINE_GET_CLASS(ms);
 
-    /*
-     * TODO: Add a SMPCompatProps.has_caches flag to avoid useless updates
-     * if user didn't set smp_cache.
-     */
-    if (!x86_cpu_update_smp_cache_topo(ms, cpu, errp)) {
-        return;
+    if (mc->smp_props.has_caches) {
+        if (!x86_cpu_update_smp_cache_topo(ms, cpu, errp)) {
+            return;
+        }
     }
 
     qemu_register_reset(x86_cpu_machine_reset_cb, cpu);