Such helper is based on the existing functions to fetch a CPUID and
MSR policies, but uses the xc_cpu_policy_t type to return the data to
the caller.

No user of the interface introduced on the patch.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
---
Changes since v1:
 - Uniformly return -1 on error from xc_cpu_policy_get_domain.
---
 tools/include/xenctrl.h         |  2 ++
 tools/libs/guest/xg_cpuid_x86.c | 25 +++++++++++++++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/tools/include/xenctrl.h b/tools/include/xenctrl.h
index 187df5c5d2d..34d979d11da 100644
--- a/tools/include/xenctrl.h
+++ b/tools/include/xenctrl.h
@@ -2599,6 +2599,8 @@ void xc_cpu_policy_destroy(xc_cpu_policy_t policy);
 /* Retrieve a system policy, or get/set a domains policy. */
 int xc_cpu_policy_get_system(xc_interface *xch, unsigned int policy_idx,
                              xc_cpu_policy_t policy);
+int xc_cpu_policy_get_domain(xc_interface *xch, uint32_t domid,
+                             xc_cpu_policy_t policy);
 
 int xc_get_cpu_levelling_caps(xc_interface *xch, uint32_t *caps);
 int xc_get_cpu_featureset(xc_interface *xch, uint32_t index,
diff --git a/tools/libs/guest/xg_cpuid_x86.c b/tools/libs/guest/xg_cpuid_x86.c
index 78fbc7db9d3..1394e503f3d 100644
--- a/tools/libs/guest/xg_cpuid_x86.c
+++ b/tools/libs/guest/xg_cpuid_x86.c
@@ -732,3 +732,28 @@ int xc_cpu_policy_get_system(xc_interface *xch, unsigned int policy_idx,
 
     return rc;
 }
+
+int xc_cpu_policy_get_domain(xc_interface *xch, uint32_t domid,
+                             xc_cpu_policy_t policy)
+{
+    unsigned int nr_leaves = ARRAY_SIZE(policy->leaves);
+    unsigned int nr_entries = ARRAY_SIZE(policy->entries);
+    int rc;
+
+    rc = xc_get_domain_cpu_policy(xch, domid, &nr_leaves, policy->leaves,
+                                  &nr_entries, policy->entries);
+    if ( rc )
+    {
+        PERROR("Failed to obtain domain %u policy", domid);
+        return rc;
+    }
+
+    rc = deserialize_policy(xch, policy, nr_leaves, nr_entries);
+    if ( rc )
+    {
+        errno = -rc;
+        rc = -1;
+    }
+
+    return rc;
+}
-- 
2.30.1