[Qemu-devel] [PATCH] vl.c: make sure maxcpus matches topology to prevent migration failure

[Igor Mammedov]

Topology (threads*cores*sockets) must match maxcpus to be valid,
otherwise we could start QEMU with invalid topology that throws
a error on migration destination side, that should not be reachable:
Source:
  -smp 8,maxcpus=64,cores=1,threads=8,sockets=1
// hotplug cpus upto maxcpus
Destination:
  -smp 64,maxcpus=64,cores=1,threads=8,sockets=1
  qemu: cpu topology: sockets (1) * cores (1) * threads (8) < smp_cpus (64)

Signed-off-by: Igor Mammedov <imamm...@redhat.com>
---
 vl.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/vl.c b/vl.c
index 16b913f..2b35e0c 100644
--- a/vl.c
+++ b/vl.c
@@ -1238,10 +1238,10 @@ static void smp_parse(QemuOpts *opts)
             exit(1);
         }
 
-        if (sockets * cores * threads > max_cpus) {
+        if (sockets * cores * threads != max_cpus) {
             error_report("cpu topology: "
-                         "sockets (%u) * cores (%u) * threads (%u) > "
-                         "maxcpus (%u)",
+                         "sockets (%u) * cores (%u) * threads (%u) not equal 
to"
+                         " maxcpus (%u)",
                          sockets, cores, threads, max_cpus);
             exit(1);
         }
-- 
2.7.4