[PULL,28/34] i386/cpu: add has_caches flag to check smp_cache configuration

Commit Message

Paolo Bonzini Feb. 27, 2025, 2:19 p.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]>
Reviewed-by: Michael S. Tsirkin <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Paolo Bonzini <[e-mail]>
---
 include/hw/boards.h   |  3 +++
 hw/core/machine-smp.c |  2 ++
 target/i386/cpu.c     | 11 +++++------
 3 files changed, 10 insertions(+), 6 deletions(-)

Patch

diff --git a/include/hw/boards.h b/include/hw/boards.h
index 9360d1ce394..f22b2e7fc75 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/hw/core/machine-smp.c b/hw/core/machine-smp.c
index 4e020c358b6..0be0ac044c2 100644
--- a/hw/core/machine-smp.c
+++ b/hw/core/machine-smp.c
@@ -332,6 +332,8 @@  bool machine_parse_smp_cache(MachineState *ms,
             return false;
         }
     }
+
+    mc->smp_props.has_caches = true;
     return true;
 }
 
diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 005ca4235df..2f9c604552b 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -8203,13 +8203,12 @@  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);