[PATCH v4 03/15] libxl: introduce libxl_get_nr_cpus()

[Dario Faggioli <dario.faggioli@citrix.com>]

to retrieve the actual number of pCPUs on the host.

Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
---
 tools/libxl/libxl.h       |    3 +++
 tools/libxl/libxl_utils.c |   18 ++++++++++++++++++
 2 files changed, 21 insertions(+)

diff --git a/tools/libxl/libxl.h b/tools/libxl/libxl.h
index a9663e4..2fab5ba 100644
--- a/tools/libxl/libxl.h
+++ b/tools/libxl/libxl.h
@@ -652,6 +652,9 @@ int libxl_domain_preserve(libxl_ctx *ctx, uint32_t domid, libxl_domain_create_in
 /* get max. number of cpus supported by hypervisor */
 int libxl_get_max_cpus(libxl_ctx *ctx);
 
+/* get the actual number of online cpus on the host */
+int libxl_get_nr_cpus(libxl_ctx *ctx);
+
 /* get max. number of NUMA nodes supported by hypervisor */
 int libxl_get_max_nodes(libxl_ctx *ctx);
 
diff --git a/tools/libxl/libxl_utils.c b/tools/libxl/libxl_utils.c
index 1815422..8763070 100644
--- a/tools/libxl/libxl_utils.c
+++ b/tools/libxl/libxl_utils.c
@@ -774,6 +774,24 @@ int libxl_get_max_cpus(libxl_ctx *ctx)
     return max_cpus <= 0 ? ERROR_FAIL : max_cpus;
 }
 
+int libxl_get_nr_cpus(libxl_ctx *ctx)
+{
+    GC_INIT(ctx);
+    xc_physinfo_t physinfo = { 0 };
+    int rc = 0;
+
+    if (xc_physinfo(ctx->xch, &physinfo)) {
+        LOGE(ERROR, "xc_physinfo failed.");
+        rc = ERROR_FAIL;
+        goto out;
+    }
+    rc = physinfo.nr_cpus;
+
+ out:
+    GC_FREE;
+    return rc;
+}
+
 int libxl_get_max_nodes(libxl_ctx *ctx)
 {
     int max_nodes = xc_get_max_nodes(ctx->xch);