[PATCH v7 02/15] machine: Minor refactor/fix for the smp parsers

[Yanan Wang <wangyanan55@huawei.com>]

To pave the way for the functional improvement in later patches,
make some refactor/cleanup for the smp parsers, including using
local maxcpus instead of ms->smp.max_cpus in the calculation,
defaulting dies to 0 initially like other members, cleanup the
sanity check for dies.

We actually also fix a hidden defect by avoiding directly using
the provided *zero value* in the calculation, which could cause
a segment fault (e.g. using dies=0 in the calculation).

Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
---
 hw/core/machine.c | 18 ++++++++++--------
 hw/i386/pc.c      | 23 ++++++++++++++---------
 2 files changed, 24 insertions(+), 17 deletions(-)

diff --git a/hw/core/machine.c b/hw/core/machine.c
index 3b5df9b002..bcced1e1c4 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -749,8 +749,9 @@ static void smp_parse(MachineState *ms, SMPConfiguration *config, Error **errp)
     unsigned sockets = config->has_sockets ? config->sockets : 0;
     unsigned cores   = config->has_cores ? config->cores : 0;
     unsigned threads = config->has_threads ? config->threads : 0;
+    unsigned maxcpus = config->has_maxcpus ? config->maxcpus : 0;
 
-    if (config->has_dies && config->dies != 0 && config->dies != 1) {
+    if (config->has_dies && config->dies > 1) {
         error_setg(errp, "dies not supported by this machine's CPU topology");
         return;
     }
@@ -763,8 +764,8 @@ static void smp_parse(MachineState *ms, SMPConfiguration *config, Error **errp)
             sockets = sockets > 0 ? sockets : 1;
             cpus = cores * threads * sockets;
         } else {
-            ms->smp.max_cpus = config->has_maxcpus ? config->maxcpus : cpus;
-            sockets = ms->smp.max_cpus / (cores * threads);
+            maxcpus = maxcpus > 0 ? maxcpus : cpus;
+            sockets = maxcpus / (cores * threads);
         }
     } else if (cores == 0) {
         threads = threads > 0 ? threads : 1;
@@ -781,26 +782,27 @@ static void smp_parse(MachineState *ms, SMPConfiguration *config, Error **errp)
         return;
     }
 
-    ms->smp.max_cpus = config->has_maxcpus ? config->maxcpus : cpus;
+    maxcpus = maxcpus > 0 ? maxcpus : cpus;
 
-    if (ms->smp.max_cpus < cpus) {
+    if (maxcpus < cpus) {
         error_setg(errp, "maxcpus must be equal to or greater than smp");
         return;
     }
 
-    if (sockets * cores * threads != ms->smp.max_cpus) {
+    if (sockets * cores * threads != maxcpus) {
         error_setg(errp, "Invalid CPU topology: "
                    "sockets (%u) * cores (%u) * threads (%u) "
                    "!= maxcpus (%u)",
                    sockets, cores, threads,
-                   ms->smp.max_cpus);
+                   maxcpus);
         return;
     }
 
     ms->smp.cpus = cpus;
+    ms->smp.sockets = sockets;
     ms->smp.cores = cores;
     ms->smp.threads = threads;
-    ms->smp.sockets = sockets;
+    ms->smp.max_cpus = maxcpus;
 }
 
 static void machine_get_smp(Object *obj, Visitor *v, const char *name,
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index c2b9d62a35..acd31af452 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -716,9 +716,13 @@ static void pc_smp_parse(MachineState *ms, SMPConfiguration *config, Error **err
 {
     unsigned cpus    = config->has_cpus ? config->cpus : 0;
     unsigned sockets = config->has_sockets ? config->sockets : 0;
-    unsigned dies    = config->has_dies ? config->dies : 1;
+    unsigned dies    = config->has_dies ? config->dies : 0;
     unsigned cores   = config->has_cores ? config->cores : 0;
     unsigned threads = config->has_threads ? config->threads : 0;
+    unsigned maxcpus = config->has_maxcpus ? config->maxcpus : 0;
+
+    /* directly default dies to 1 if it's omitted */
+    dies = dies > 0 ? dies : 1;
 
     /* compute missing values, prefer sockets over cores over threads */
     if (cpus == 0 || sockets == 0) {
@@ -728,8 +732,8 @@ static void pc_smp_parse(MachineState *ms, SMPConfiguration *config, Error **err
             sockets = sockets > 0 ? sockets : 1;
             cpus = cores * threads * dies * sockets;
         } else {
-            ms->smp.max_cpus = config->has_maxcpus ? config->maxcpus : cpus;
-            sockets = ms->smp.max_cpus / (cores * threads * dies);
+            maxcpus = maxcpus > 0 ? maxcpus : cpus;
+            sockets = maxcpus / (dies * cores * threads);
         }
     } else if (cores == 0) {
         threads = threads > 0 ? threads : 1;
@@ -746,27 +750,28 @@ static void pc_smp_parse(MachineState *ms, SMPConfiguration *config, Error **err
         return;
     }
 
-    ms->smp.max_cpus = config->has_maxcpus ? config->maxcpus : cpus;
+    maxcpus = maxcpus > 0 ? maxcpus : cpus;
 
-    if (ms->smp.max_cpus < cpus) {
+    if (maxcpus < cpus) {
         error_setg(errp, "maxcpus must be equal to or greater than smp");
         return;
     }
 
-    if (sockets * dies * cores * threads != ms->smp.max_cpus) {
+    if (sockets * dies * cores * threads != maxcpus) {
         error_setg(errp, "Invalid CPU topology deprecated: "
                    "sockets (%u) * dies (%u) * cores (%u) * threads (%u) "
                    "!= maxcpus (%u)",
                    sockets, dies, cores, threads,
-                   ms->smp.max_cpus);
+                   maxcpus);
         return;
     }
 
     ms->smp.cpus = cpus;
-    ms->smp.cores = cores;
-    ms->smp.threads = threads;
     ms->smp.sockets = sockets;
     ms->smp.dies = dies;
+    ms->smp.cores = cores;
+    ms->smp.threads = threads;
+    ms->smp.maxcpus = maxcpus;
 }
 
 static
-- 
2.19.1