[RFC PATCH 1/6] libxl: Pass max_vcpus to Qemu in case of PVH domain (Arm) as well

[Sergiy Kibrik <Sergiy_Kibrik@xxxxxxxx>]

From: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>

The number of vCPUs used for the IOREQ configuration (machine->smp.cpus)
should really match the system value as for each vCPU we setup a dedicated
evtchn for the communication with Xen at the runtime. This is needed
for the IOREQ to be properly configured and work if the involved domain
has more than one vCPU assigned.

Note that Qemu should set mc->max_cpus to GUEST_MAX_VCPUS in
xen_arm_machine_class_init().

Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
Signed-off-by: Sergiy Kibrik <Sergiy_Kibrik@xxxxxxxx>
---
 tools/libs/light/libxl_dm.c | 28 ++++++++++++++++------------
 1 file changed, 16 insertions(+), 12 deletions(-)

diff --git a/tools/libs/light/libxl_dm.c b/tools/libs/light/libxl_dm.c
index 14b593110f..0b2548d35b 100644
--- a/tools/libs/light/libxl_dm.c
+++ b/tools/libs/light/libxl_dm.c
@@ -1553,18 +1553,6 @@ static int libxl__build_device_model_args_new(libxl__gc 
*gc,
         if (!libxl__acpi_defbool_val(b_info)) {
             flexarray_append(dm_args, "-no-acpi");
         }
-        if (b_info->max_vcpus > 1) {
-            flexarray_append(dm_args, "-smp");
-            if (b_info->avail_vcpus.size) {
-                int nr_set_cpus = 0;
-                nr_set_cpus = libxl_bitmap_count_set(&b_info->avail_vcpus);
-
-                flexarray_append(dm_args, GCSPRINTF("%d,maxcpus=%d",
-                                                    nr_set_cpus,
-                                                    b_info->max_vcpus));
-            } else
-                flexarray_append(dm_args, GCSPRINTF("%d", b_info->max_vcpus));
-        }
         for (i = 0; i < num_nics; i++) {
             if (nics[i].nictype == LIBXL_NIC_TYPE_VIF_IOEMU) {
                 char *smac = GCSPRINTF(LIBXL_MAC_FMT,
@@ -1800,6 +1788,22 @@ static int libxl__build_device_model_args_new(libxl__gc 
*gc,
     for (i = 0; b_info->extra && b_info->extra[i] != NULL; i++)
         flexarray_append(dm_args, b_info->extra[i]);
 
+    if (b_info->type == LIBXL_DOMAIN_TYPE_HVM ||
+        b_info->type == LIBXL_DOMAIN_TYPE_PVH) {
+        if (b_info->max_vcpus > 1) {
+            flexarray_append(dm_args, "-smp");
+            if (b_info->avail_vcpus.size) {
+                int nr_set_cpus = 0;
+                nr_set_cpus = libxl_bitmap_count_set(&b_info->avail_vcpus);
+
+                flexarray_append(dm_args, GCSPRINTF("%d,maxcpus=%d",
+                                                    nr_set_cpus,
+                                                    b_info->max_vcpus));
+            } else
+                flexarray_append(dm_args, GCSPRINTF("%d", b_info->max_vcpus));
+        }
+    }
+
     flexarray_append(dm_args, "-machine");
     switch (b_info->type) {
     case LIBXL_DOMAIN_TYPE_PVH:
-- 
2.25.1