[Xen-devel] [PATCH RFC 7/8] libxl: introduce topology fields

[Joao Martins <joao.m.martins@xxxxxxxxxx>]

Currently there is "smt" option that changes from a flat core topology
to a core+thread topology. This patch adds more expressive options for
describing the topology as seen by the guest i.e. sockets, cores and
threads to adjust cpu topology as seen by the guest.

Signed-off-by: Joao Martins <joao.m.martins@xxxxxxxxxx>
---
CC: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
CC: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
CC: Ian Campbell <ian.campbell@xxxxxxxxxx>
CC: Wei Liu <wei.liu2@xxxxxxxxxx>
---
 tools/libxl/libxl_dom.c     | 18 ++++++++++++------
 tools/libxl/libxl_types.idl |  4 ++++
 2 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/tools/libxl/libxl_dom.c b/tools/libxl/libxl_dom.c
index ff9356d..1e6d9ab 100644
--- a/tools/libxl/libxl_dom.c
+++ b/tools/libxl/libxl_dom.c
@@ -507,14 +507,20 @@ int libxl__build_post(libxl__gc *gc, uint32_t domid,
     }
 
     libxl_cpuid_apply_policy(ctx, domid);
-    if (info->type == LIBXL_DOMAIN_TYPE_HVM
-        && libxl_defbool_val(info->smt)) {
+    if (info->type == LIBXL_DOMAIN_TYPE_HVM) {
 
-        uint32_t threads = 0;
+        uint32_t threads = 0, cores = 0;
+
+        if (libxl_defbool_val(info->smt)
+            && !libxl__count_threads_per_core(gc, &threads))
+            cores = info->max_vcpus / threads;
+        else if (info->topology.cores) {
+            cores = info->topology.cores;
+            threads = info->topology.threads;
+        }
 
-        if (!libxl__count_threads_per_core(gc, &threads))
-            libxl__cpuid_set_topology(ctx, domid,
-                                      info->max_vcpus / threads, threads);
+        if (cores && threads)
+            libxl__cpuid_set_topology(ctx, domid, cores, threads);
     }
 
     if (info->cpuid != NULL)
diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
index fa4725a..caba626 100644
--- a/tools/libxl/libxl_types.idl
+++ b/tools/libxl/libxl_types.idl
@@ -422,6 +422,10 @@ libxl_domain_build_info = Struct("domain_build_info",[
     ("vcpu_hard_affinity", Array(libxl_bitmap, "num_vcpu_hard_affinity")),
     ("vcpu_soft_affinity", Array(libxl_bitmap, "num_vcpu_soft_affinity")),
     ("smt",             libxl_defbool),
+    ("topology",        Struct(None, [("sockets", integer),
+                                      ("cores",   integer),
+                                      ("threads", integer),
+                                      ])),
     ("numa_placement",  libxl_defbool),
     ("tsc_mode",        libxl_tsc_mode),
     ("max_memkb",       MemKB),
-- 
2.1.4


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