machine: Improve the error reporting of smp parsing

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>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20210929025816.21076-7-wangyanan55@huawei.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

2 files changed, 19 insertions, 27 deletions

diff --git a/hw/core/machine.c b/hw/core/machine.c
index d8f458db..e38ab76 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -782,25 +782,21 @@ 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 f24a1d7..9216ad1 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -749,25 +749,21 @@ 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;
     }