[PATCH for-6.2 v2 03/11] machine: Uniformly use maxcpus to calculate the omitted parameters

[Yanan Wang]

We are currently using maxcpus to calculate the omitted sockets
but using cpus to calculate the omitted cores/threads. This makes
cmdlines like:
  -smp cpus=8,maxcpus=16
  -smp cpus=8,cores=4,maxcpus=16
  -smp cpus=8,threads=2,maxcpus=16
work fine but the ones like:
  -smp cpus=8,sockets=2,maxcpus=16
  -smp cpus=8,sockets=2,cores=4,maxcpus=16
  -smp cpus=8,sockets=2,threads=2,maxcpus=16
break the invalid cpu topology check.

Since we require for the valid config that the sum of "sockets * cores
* dies * threads" should equal to the maxcpus, we should uniformly use
maxcpus to calculate their omitted values.

Also the if-branch of "cpus == 0 || sockets == 0" was splited into two
branches of "cpus == 0" and "sockets == 0" so that we can clearly read
that we are parsing -smp cmdlines with a preference of cpus over sockets
over cores over threads.

Note: change in this patch won't affect any existing working cmdlines
but improves consistency and allow more incomplete configs to be valid.

Signed-off-by: Yanan Wang <wangyana...@huawei.com>
---
 hw/core/machine.c | 30 +++++++++++++++---------------
 1 file changed, 15 insertions(+), 15 deletions(-)

diff --git a/hw/core/machine.c b/hw/core/machine.c
index ed6712e964..c9f15b15a5 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -768,24 +768,26 @@ static void smp_parse(MachineState *ms, SMPConfiguration 
*config, Error **errp)
     }
 
     /* compute missing values, prefer sockets over cores over threads */
-    if (cpus == 0 || sockets == 0) {
+    maxcpus = maxcpus > 0 ? maxcpus : cpus;
+
+    if (cpus == 0) {
+        sockets = sockets > 0 ? sockets : 1;
         cores = cores > 0 ? cores : 1;
         threads = threads > 0 ? threads : 1;
-        if (cpus == 0) {
-            sockets = sockets > 0 ? sockets : 1;
-            cpus = sockets * dies * cores * threads;
-        } else {
-            maxcpus = maxcpus > 0 ? maxcpus : cpus;
-            sockets = maxcpus / (dies * cores * threads);
-        }
+        cpus = sockets * dies * cores * threads;
+        maxcpus = maxcpus > 0 ? maxcpus : cpus;
+    } else 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 = cpus / (sockets * dies * threads);
-        cores = cores > 0 ? cores : 1;
+        cores = maxcpus / (sockets * dies * threads);
     } else if (threads == 0) {
-        threads = cpus / (sockets * dies * cores);
-        threads = threads > 0 ? threads : 1;
-    } else if (sockets * dies * cores * threads < cpus) {
+        threads = maxcpus / (sockets * dies * cores);
+    }
+
+    if (sockets * dies * cores * threads < cpus) {
         g_autofree char *dies_msg = g_strdup_printf(
             mc->smp_dies_supported ? " * dies (%u)" : "", dies);
         error_setg(errp, "cpu topology: "
@@ -795,8 +797,6 @@ static void smp_parse(MachineState *ms, SMPConfiguration 
*config, Error **errp)
         return;
     }
 
-    maxcpus = maxcpus > 0 ? maxcpus : cpus;
-
     if (maxcpus < cpus) {
         error_setg(errp, "maxcpus must be equal to or greater than smp");
         return;
-- 
2.19.1