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-rw-r--r--hw/arm/virt.c1
-rw-r--r--hw/core/machine.c35
-rw-r--r--hw/i386/pc.c35
-rw-r--r--hw/i386/pc_piix.c1
-rw-r--r--hw/i386/pc_q35.c1
-rw-r--r--hw/ppc/spapr.c1
-rw-r--r--hw/s390x/s390-virtio-ccw.c1
-rw-r--r--include/hw/boards.h1
-rw-r--r--qemu-options.hx3
9 files changed, 60 insertions, 19 deletions
diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 1d59f0e59f..8c13deb5db 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -2815,6 +2815,7 @@ static void virt_machine_6_1_options(MachineClass *mc)
 
     virt_machine_6_2_options(mc);
     compat_props_add(mc->compat_props, hw_compat_6_1, hw_compat_6_1_len);
+    mc->smp_prefer_sockets = true;
 
     /* qemu ITS was introduced with 6.2 */
     vmc->no_tcg_its = true;
diff --git a/hw/core/machine.c b/hw/core/machine.c
index e38ab760e6..f2a34d98c0 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -748,6 +748,7 @@ void machine_set_cpu_numa_node(MachineState *machine,
 
 static void smp_parse(MachineState *ms, SMPConfiguration *config, Error **errp)
 {
+    MachineClass *mc = MACHINE_GET_CLASS(ms);
     unsigned cpus    = config->has_cpus ? config->cpus : 0;
     unsigned sockets = config->has_sockets ? config->sockets : 0;
     unsigned cores   = config->has_cores ? config->cores : 0;
@@ -759,7 +760,7 @@ static void smp_parse(MachineState *ms, SMPConfiguration *config, Error **errp)
         return;
     }
 
-    /* compute missing values, prefer sockets over cores over threads */
+    /* compute missing values based on the provided ones */
     if (cpus == 0 && maxcpus == 0) {
         sockets = sockets > 0 ? sockets : 1;
         cores = cores > 0 ? cores : 1;
@@ -767,14 +768,30 @@ static void smp_parse(MachineState *ms, SMPConfiguration *config, Error **errp)
     } else {
         maxcpus = maxcpus > 0 ? maxcpus : cpus;
 
-        if (sockets == 0) {
-            cores = cores > 0 ? cores : 1;
-            threads = threads > 0 ? threads : 1;
-            sockets = maxcpus / (cores * threads);
-        } else if (cores == 0) {
-            threads = threads > 0 ? threads : 1;
-            cores = maxcpus / (sockets * threads);
-        } else if (threads == 0) {
+        if (mc->smp_prefer_sockets) {
+            /* prefer sockets over cores before 6.2 */
+            if (sockets == 0) {
+                cores = cores > 0 ? cores : 1;
+                threads = threads > 0 ? threads : 1;
+                sockets = maxcpus / (cores * threads);
+            } else if (cores == 0) {
+                threads = threads > 0 ? threads : 1;
+                cores = maxcpus / (sockets * threads);
+            }
+        } else {
+            /* prefer cores over sockets since 6.2 */
+            if (cores == 0) {
+                sockets = sockets > 0 ? sockets : 1;
+                threads = threads > 0 ? threads : 1;
+                cores = maxcpus / (sockets * threads);
+            } else if (sockets == 0) {
+                threads = threads > 0 ? threads : 1;
+                sockets = maxcpus / (cores * threads);
+            }
+        }
+
+        /* try to calculate omitted threads at last */
+        if (threads == 0) {
             threads = maxcpus / (sockets * cores);
         }
     }
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 9216ad163d..6cc32f4048 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -716,6 +716,7 @@ void pc_acpi_smi_interrupt(void *opaque, int irq, int level)
  */
 static void pc_smp_parse(MachineState *ms, SMPConfiguration *config, Error **errp)
 {
+    MachineClass *mc = MACHINE_GET_CLASS(ms);
     unsigned cpus    = config->has_cpus ? config->cpus : 0;
     unsigned sockets = config->has_sockets ? config->sockets : 0;
     unsigned dies    = config->has_dies ? config->dies : 0;
@@ -726,7 +727,7 @@ static void pc_smp_parse(MachineState *ms, SMPConfiguration *config, Error **err
     /* directly default dies to 1 if it's omitted */
     dies = dies > 0 ? dies : 1;
 
-    /* compute missing values, prefer sockets over cores over threads */
+    /* compute missing values based on the provided ones */
     if (cpus == 0 && maxcpus == 0) {
         sockets = sockets > 0 ? sockets : 1;
         cores = cores > 0 ? cores : 1;
@@ -734,14 +735,30 @@ static void pc_smp_parse(MachineState *ms, SMPConfiguration *config, Error **err
     } else {
         maxcpus = maxcpus > 0 ? maxcpus : cpus;
 
-        if (sockets == 0) {
-            cores = cores > 0 ? cores : 1;
-            threads = threads > 0 ? threads : 1;
-            sockets = maxcpus / (dies * cores * threads);
-        } else if (cores == 0) {
-            threads = threads > 0 ? threads : 1;
-            cores = maxcpus / (sockets * dies * threads);
-        } else if (threads == 0) {
+        if (mc->smp_prefer_sockets) {
+            /* prefer sockets over cores before 6.2 */
+            if (sockets == 0) {
+                cores = cores > 0 ? cores : 1;
+                threads = threads > 0 ? threads : 1;
+                sockets = maxcpus / (dies * cores * threads);
+            } else if (cores == 0) {
+                threads = threads > 0 ? threads : 1;
+                cores = maxcpus / (sockets * dies * threads);
+            }
+        } else {
+            /* prefer cores over sockets since 6.2 */
+            if (cores == 0) {
+                sockets = sockets > 0 ? sockets : 1;
+                threads = threads > 0 ? threads : 1;
+                cores = maxcpus / (sockets * dies * threads);
+            } else if (sockets == 0) {
+                threads = threads > 0 ? threads : 1;
+                sockets = maxcpus / (dies * cores * threads);
+            }
+        }
+
+        /* try to calculate omitted threads at last */
+        if (threads == 0) {
             threads = maxcpus / (sockets * dies * cores);
         }
     }
diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
index 6cc834aff6..932e6e2cfe 100644
--- a/hw/i386/pc_piix.c
+++ b/hw/i386/pc_piix.c
@@ -432,6 +432,7 @@ static void pc_i440fx_6_1_machine_options(MachineClass *m)
     m->is_default = false;
     compat_props_add(m->compat_props, hw_compat_6_1, hw_compat_6_1_len);
     compat_props_add(m->compat_props, pc_compat_6_1, pc_compat_6_1_len);
+    m->smp_prefer_sockets = true;
 }
 
 DEFINE_I440FX_MACHINE(v6_1, "pc-i440fx-6.1", NULL,
diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
index 5481d5c965..57ab07e5b7 100644
--- a/hw/i386/pc_q35.c
+++ b/hw/i386/pc_q35.c
@@ -372,6 +372,7 @@ static void pc_q35_6_1_machine_options(MachineClass *m)
     m->alias = NULL;
     compat_props_add(m->compat_props, hw_compat_6_1, hw_compat_6_1_len);
     compat_props_add(m->compat_props, pc_compat_6_1, pc_compat_6_1_len);
+    m->smp_prefer_sockets = true;
 }
 
 DEFINE_Q35_MACHINE(v6_1, "pc-q35-6.1", NULL,
diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index b7bee5f4ff..2986108b5a 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -4685,6 +4685,7 @@ static void spapr_machine_6_1_class_options(MachineClass *mc)
     spapr_machine_6_2_class_options(mc);
     compat_props_add(mc->compat_props, hw_compat_6_1, hw_compat_6_1_len);
     smc->pre_6_2_numa_affinity = true;
+    mc->smp_prefer_sockets = true;
 }
 
 DEFINE_SPAPR_MACHINE(6_1, "6.1", false);
diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
index 61aeccb163..5401c985cf 100644
--- a/hw/s390x/s390-virtio-ccw.c
+++ b/hw/s390x/s390-virtio-ccw.c
@@ -814,6 +814,7 @@ static void ccw_machine_6_1_class_options(MachineClass *mc)
 {
     ccw_machine_6_2_class_options(mc);
     compat_props_add(mc->compat_props, hw_compat_6_1, hw_compat_6_1_len);
+    mc->smp_prefer_sockets = true;
 }
 DEFINE_CCW_MACHINE(6_1, "6.1", false);
 
diff --git a/include/hw/boards.h b/include/hw/boards.h
index 463a5514f9..2ae039b74f 100644
--- a/include/hw/boards.h
+++ b/include/hw/boards.h
@@ -247,6 +247,7 @@ struct MachineClass {
     bool nvdimm_supported;
     bool numa_mem_supported;
     bool auto_enable_numa;
+    bool smp_prefer_sockets;
     const char *default_ram_id;
 
     HotplugHandler *(*get_hotplug_handler)(MachineState *machine,
diff --git a/qemu-options.hx b/qemu-options.hx
index 2eac830fdb..8ef178180d 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -244,7 +244,8 @@ SRST
     Historically preference was given to the coarsest topology parameters
     when computing missing values (ie sockets preferred over cores, which
     were preferred over threads), however, this behaviour is considered
-    liable to change.
+    liable to change. Prior to 6.2 the preference was sockets over cores
+    over threads. Since 6.2 the preference is cores over sockets over threads.
 ERST
 
 DEF("numa", HAS_ARG, QEMU_OPTION_numa,