[PATCH v7 05/15] machine: Improve the error reporting of smp parsing

[Yanan Wang]

We have two requirements for a valid SMP configuration:
the product of "sockets * cores * threads" must represent all the
possible cpus, i.e., max_cpus, and then must include the initially
present cpus, i.e., smp_cpus.

So we only need to ensure 1) "sockets * cores * threads == maxcpus"
at first and then ensure 2) "maxcpus >= cpus". With a reasonable
order of the sanity check, we can simplify the error reporting code.
When reporting an error message we also report the exact value of
each topology member to make users easily see what's going on.

Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Reviewed-by: Pankaj Gupta <pankaj.gupta@ionos.com>
---
 hw/core/machine.c | 22 +++++++++-------------
 hw/i386/pc.c      | 24 ++++++++++--------------
 2 files changed, 19 insertions(+), 27 deletions(-)

diff --git a/hw/core/machine.c b/hw/core/machine.c
index 85908abc77..093c0d382d 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -779,25 +779,21 @@ static void smp_parse(MachineState *ms, SMPConfiguration 
*config, Error **errp)
     maxcpus = maxcpus > 0 ? maxcpus : sockets * cores * threads;
     cpus = cpus > 0 ? cpus : maxcpus;
 
-    if (sockets * cores * threads < cpus) {
-        error_setg(errp, "cpu topology: "
-                   "sockets (%u) * cores (%u) * threads (%u) < "
-                   "smp_cpus (%u)",
-                   sockets, cores, threads, cpus);
+    if (sockets * cores * threads != maxcpus) {
+        error_setg(errp, "Invalid CPU topology: "
+                   "product of the hierarchy must match maxcpus: "
+                   "sockets (%u) * cores (%u) * threads (%u) "
+                   "!= maxcpus (%u)",
+                   sockets, cores, threads, maxcpus);
         return;
     }
 
     if (maxcpus < cpus) {
-        error_setg(errp, "maxcpus must be equal to or greater than smp");
-        return;
-    }
-
-    if (sockets * cores * threads != maxcpus) {
         error_setg(errp, "Invalid CPU topology: "
+                   "maxcpus must be equal to or greater than smp: "
                    "sockets (%u) * cores (%u) * threads (%u) "
-                   "!= maxcpus (%u)",
-                   sockets, cores, threads,
-                   maxcpus);
+                   "== maxcpus (%u) < smp_cpus (%u)",
+                   sockets, cores, threads, maxcpus, cpus);
         return;
     }
 
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 9ad7ae5254..fcf6905219 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -747,25 +747,21 @@ static void pc_smp_parse(MachineState *ms, 
SMPConfiguration *config, Error **err
     maxcpus = maxcpus > 0 ? maxcpus : sockets * dies * cores * threads;
     cpus = cpus > 0 ? cpus : maxcpus;
 
-    if (sockets * dies * cores * threads < cpus) {
-        error_setg(errp, "cpu topology: "
-                   "sockets (%u) * dies (%u) * cores (%u) * threads (%u) < "
-                   "smp_cpus (%u)",
-                   sockets, dies, cores, threads, cpus);
+    if (sockets * dies * cores * threads != maxcpus) {
+        error_setg(errp, "Invalid CPU topology: "
+                   "product of the hierarchy must match maxcpus: "
+                   "sockets (%u) * dies (%u) * cores (%u) * threads (%u) "
+                   "!= maxcpus (%u)",
+                   sockets, dies, cores, threads, maxcpus);
         return;
     }
 
     if (maxcpus < cpus) {
-        error_setg(errp, "maxcpus must be equal to or greater than smp");
-        return;
-    }
-
-    if (sockets * dies * cores * threads != maxcpus) {
-        error_setg(errp, "Invalid CPU topology deprecated: "
+        error_setg(errp, "Invalid CPU topology: "
+                   "maxcpus must be equal to or greater than smp: "
                    "sockets (%u) * dies (%u) * cores (%u) * threads (%u) "
-                   "!= maxcpus (%u)",
-                   sockets, dies, cores, threads,
-                   maxcpus);
+                   "== maxcpus (%u) < smp_cpus (%u)",
+                   sockets, dies, cores, threads, maxcpus, cpus);
         return;
     }
 
-- 
2.19.1