[Qemu-devel] [RFC PATCH v0 1/9] vl: Don't allow CPU toplogies with partially filled cores

[Bharata B Rao <bharata@linux.vnet.ibm.com>]

Prevent guests from booting with CPU topologies that have partially
filled CPU cores or can result in partially filled CPU cores after CPU
hotplug like

-smp 15,sockets=1,cores=4,threads=4,maxcpus=16 or
-smp 15,sockets=1,cores=4,threads=4,maxcpus=17 or

Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
---
 vl.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/vl.c b/vl.c
index 525929b..e656f53 100644
--- a/vl.c
+++ b/vl.c
@@ -1252,6 +1252,19 @@ static void smp_parse(QemuOpts *opts)
         smp_cores = cores > 0 ? cores : 1;
         smp_threads = threads > 0 ? threads : 1;
 
+        if (smp_cpus % smp_threads) {
+            error_report("cpu topology: "
+                         "smp_cpus (%u) should be multiple of threads (%u)",
+                         smp_cpus, smp_threads);
+            exit(1);
+        }
+
+        if (max_cpus % smp_threads) {
+            error_report("cpu topology: "
+                         "maxcpus (%u) should be multiple of threads (%u)",
+                         max_cpus, smp_threads);
+            exit(1);
+        }
     }
 
     if (max_cpus == 0) {
-- 
2.1.0