libxl/vcpu-set - allow to decrease vcpu count on overcommitted guests (v5)

We have a check to warn the user if they are overcommitting.
But the check only checks the hosts CPU amount and does
not take into account the case when the user is trying to fix
the overcommit. That is - they want to limit the amount of
online VCPUs.

This fix allows the user to offline vCPUs without any
warnings when they are running an overcommitted guest.

Also fix the extra space in the message.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>

diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index b121d758a4a7b2d4f575c16e61ed67ec701a9579..648ca08d8b50049bd422c4e08e73e52dbf8626f5 100644 (file)
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -5238,12 +5238,21 @@ static int vcpuset(uint32_t domid, const char* nr_vcpus, int check_host)
      */
     if (check_host) {
         unsigned int host_cpu = libxl_get_max_cpus(ctx);
-        if (max_vcpus > host_cpu) {
-            fprintf(stderr, "You are overcommmitting! You have %d physical " \
-                    " CPUs and want %d vCPUs! Aborting, use --ignore-host to " \
-                    " continue\n", host_cpu, max_vcpus);
+        libxl_dominfo dominfo;
+
+        rc = libxl_domain_info(ctx, &dominfo, domid);
+        if (rc)
             return 1;
+
+        if (max_vcpus > dominfo.vcpu_online && max_vcpus > host_cpu) {
+            fprintf(stderr, "You are overcommmitting! You have %d physical" \
+                    " CPUs and want %d vCPUs! Aborting, use --ignore-host to" \
+                    " continue\n", host_cpu, max_vcpus);
+            rc = 1;
         }
+        libxl_dominfo_dispose(&dominfo);
+        if (rc)
+            return 1;
     }
     rc = libxl_cpu_bitmap_alloc(ctx, &cpumap, max_vcpus);
     if (rc) {