diff --git a/src/libvirt.c b/src/libvirt.c
index 45bc9b072ea8155c5deeccbfabb1c9e604073f1e..79a196a293f3487759d1d8412ce3b505cccfe013 100644
--- a/src/libvirt.c
+++ b/src/libvirt.c
@@ -5015,14 +5015,15 @@ error:
 /**
  * virDomainGetSchedulerParameters:
  * @domain: pointer to domain object
- * @params: pointer to scheduler parameter object
+ * @params: pointer to scheduler parameter objects
  *          (return value)
- * @nparams: pointer to number of scheduler parameter
- *          (this value should be same than the returned value
+ * @nparams: pointer to number of scheduler parameter objects
+ *          (this value must be at least as large as the returned value
  *           nparams of virDomainGetSchedulerType)
  *
- * Get the scheduler parameters, the @params array will be filled with the
- * values.
+ * Get all scheduler parameters, the @params array will be filled with the
+ * values and @nparams will be updated to the number of valid elements in
+ * @params.
  *
  * Returns -1 in case of error, 0 in case of success.
  */
@@ -5041,6 +5042,12 @@ virDomainGetSchedulerParameters(virDomainPtr domain,
         virDispatchError(NULL);
         return -1;
     }
+
+    if (params == NULL || nparams == NULL || *nparams <= 0) {
+        virLibDomainError(VIR_ERR_INVALID_ARG, __FUNCTION__);
+        goto error;
+    }
+
     conn = domain->conn;
 
     if (conn->driver->domainGetSchedulerParameters) {
diff --git a/src/libxl/libxl_driver.c b/src/libxl/libxl_driver.c
index 6b2d806b012ca9e6c843524738a88c9b938b176c..b85c743eaf1fa8cd8a32764c51c96084277bf792 100644
--- a/src/libxl/libxl_driver.c
+++ b/src/libxl/libxl_driver.c
@@ -2466,7 +2466,7 @@ libxlDomainGetSchedulerParameters(virDomainPtr dom, virSchedParameterPtr params,
         goto cleanup;
     }
 
-    if (*nparams != XEN_SCHED_CREDIT_NPARAM) {
+    if (*nparams < XEN_SCHED_CREDIT_NPARAM) {
         libxlError(VIR_ERR_INVALID_ARG, "%s", _("Invalid parameter count"));
         goto cleanup;
     }
@@ -2494,6 +2494,7 @@ libxlDomainGetSchedulerParameters(virDomainPtr dom, virSchedParameterPtr params,
         goto cleanup;
     }
 
+    *nparams = XEN_SCHED_CREDIT_NPARAM;
     ret = 0;
 
 cleanup:
diff --git a/src/lxc/lxc_driver.c b/src/lxc/lxc_driver.c
index 2bb592dbbb43ce03f564fd23663ca51217d4a65f..a65299bc17e20c6a779373f718baecd1c158048e 100644
--- a/src/lxc/lxc_driver.c
+++ b/src/lxc/lxc_driver.c
@@ -2234,7 +2234,7 @@ static int lxcGetSchedulerParameters(virDomainPtr domain,
     if (driver->cgroup == NULL)
         return -1;
 
-    if ((*nparams) != 1) {
+    if (*nparams < 1) {
         lxcError(VIR_ERR_INVALID_ARG,
                  "%s", _("Invalid parameter count"));
         return -1;
@@ -2264,6 +2264,7 @@ static int lxcGetSchedulerParameters(virDomainPtr domain,
     }
     params[0].type = VIR_DOMAIN_SCHED_FIELD_ULLONG;
 
+    *nparams = 1;
     ret = 0;
 
 cleanup:
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index fdb3b30059bb921db9fcabe5383510718c5f7fab..9a7286dcfa4d532280f777fc18a407f24c8416b2 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -5181,7 +5181,7 @@ static int qemuGetSchedulerParameters(virDomainPtr dom,
         goto cleanup;
     }
 
-    if ((*nparams) != 1) {
+    if (*nparams < 1) {
         qemuReportError(VIR_ERR_INVALID_ARG,
                         "%s", _("Invalid parameter count"));
         goto cleanup;
@@ -5221,6 +5221,7 @@ out:
         goto cleanup;
     }
 
+    *nparams = 1;
     ret = 0;
 
 cleanup:
diff --git a/src/test/test_driver.c b/src/test/test_driver.c
index e716c98f64cbf0a0fcc6404cae9430ec3e7726aa..2d5f48906b1632c1e1d7cabc2886e2e267ab5869 100644
--- a/src/test/test_driver.c
+++ b/src/test/test_driver.c
@@ -2652,8 +2652,8 @@ static int testDomainGetSchedulerParams(virDomainPtr domain,
         goto cleanup;
     }
 
-    if (*nparams != 1) {
-        testError(VIR_ERR_INVALID_ARG, "nparams");
+    if (*nparams < 1) {
+        testError(VIR_ERR_INVALID_ARG, "%s", _("Invalid parameter count"));
         goto cleanup;
     }
     strcpy(params[0].field, "weight");
@@ -2661,6 +2661,8 @@ static int testDomainGetSchedulerParams(virDomainPtr domain,
     /* XXX */
     /*params[0].value.ui = privdom->weight;*/
     params[0].value.ui = 50;
+
+    *nparams = 1;
     ret = 0;
 
 cleanup:
diff --git a/src/xen/xen_driver.h b/src/xen/xen_driver.h
index 8fb58320f6928740b0884b6dc76ca3a4dab38a35..20eca6e90f530eae72648a3ed775d7748c2a5276 100644
--- a/src/xen/xen_driver.h
+++ b/src/xen/xen_driver.h
@@ -60,6 +60,9 @@ extern int xenRegister (void);
 
 # define XEND_DOMAINS_DIR "/var/lib/xend/domains"
 
+# define XEN_SCHED_SEDF_NPARAM   6
+# define XEN_SCHED_CRED_NPARAM   2
+
 /* _xenUnifiedDriver:
  *
  * Entry points into the underlying Xen drivers.  This structure
diff --git a/src/xen/xen_hypervisor.c b/src/xen/xen_hypervisor.c
index 3ec6e2b6353733d37176d1cd333e69f4540415af..8d579bc593d9f9f4a1d0d4bf3ddf197c901a04a8 100644
--- a/src/xen/xen_hypervisor.c
+++ b/src/xen/xen_hypervisor.c
@@ -1207,14 +1207,14 @@ xenHypervisorGetSchedulerType(virDomainPtr domain, int *nparams)
                 if (schedulertype == NULL)
                     virReportOOMError();
                 if (nparams)
-                    *nparams = 6;
+                    *nparams = XEN_SCHED_SEDF_NPARAM;
                 break;
             case XEN_SCHEDULER_CREDIT:
                 schedulertype = strdup("credit");
                 if (schedulertype == NULL)
                     virReportOOMError();
                 if (nparams)
-                    *nparams = 2;
+                    *nparams = XEN_SCHED_CRED_NPARAM;
                 break;
             default:
                 break;
@@ -1232,8 +1232,8 @@ static const char *str_cap = "cap";
  * @domain: pointer to the Xen Hypervisor block
  * @params: pointer to scheduler parameters.
  *     This memory area should be allocated before calling.
- * @nparams:this parameter should be same as
- *     a given number of scheduler parameters.
+ * @nparams: this parameter must be at least as large as
+ *     the given number of scheduler parameters.
  *     from xenHypervisorGetSchedulerType().
  *
  * Do a low level hypercall to get scheduler parameters
@@ -1288,12 +1288,21 @@ xenHypervisorGetSchedulerParameters(virDomainPtr domain,
 
         switch (op_sys.u.getschedulerid.sched_id){
             case XEN_SCHEDULER_SEDF:
+                if (*nparams < XEN_SCHED_SEDF_NPARAM) {
+                    virXenError(VIR_ERR_INVALID_ARG,
+                                "%s", _("Invalid parameter count"));
+                    return -1;
+                }
+
                 /* TODO: Implement for Xen/SEDF */
                 TODO
                 return(-1);
             case XEN_SCHEDULER_CREDIT:
-                if (*nparams < 2)
-                    return(-1);
+                if (*nparams < XEN_SCHED_CRED_NPARAM) {
+                    virXenError(VIR_ERR_INVALID_ARG,
+                                "%s", _("Invalid parameter count"));
+                    return -1;
+                }
                 memset(&op_dom, 0, sizeof(op_dom));
                 op_dom.cmd = XEN_V2_OP_SCHEDULER;
                 op_dom.domain = (domid_t) domain->id;
@@ -1319,7 +1328,7 @@ xenHypervisorGetSchedulerParameters(virDomainPtr domain,
                 params[1].type = VIR_DOMAIN_SCHED_FIELD_UINT;
                 params[1].value.ui = op_dom.u.getschedinfo.u.credit.cap;
 
-                *nparams = 2;
+                *nparams = XEN_SCHED_CRED_NPARAM;
                 break;
             default:
                 virXenErrorFunc(VIR_ERR_INVALID_ARG, __FUNCTION__,
diff --git a/src/xen/xend_internal.c b/src/xen/xend_internal.c
index 359d5f497216511fec3ea10ac149e5eb155a307a..0fa8042adc8014faa4e51597d9b05a22dfefcba0 100644
--- a/src/xen/xend_internal.c
+++ b/src/xen/xend_internal.c
@@ -55,8 +55,6 @@
 /*
  * The number of Xen scheduler parameters
  */
-#define XEN_SCHED_SEDF_NPARAM   6
-#define XEN_SCHED_CRED_NPARAM   2
 
 #define XEND_RCV_BUF_MAX_LEN 65536
 
@@ -3607,8 +3605,7 @@ xenDaemonGetSchedulerParameters(virDomainPtr domain,
     int sched_nparam = 0;
     int ret = -1;
 
-    if ((domain == NULL) || (domain->conn == NULL) || (domain->name == NULL)
-        || (params == NULL) || (nparams == NULL)) {
+    if ((domain == NULL) || (domain->conn == NULL) || (domain->name == NULL)) {
         virXendError(VIR_ERR_INVALID_ARG, __FUNCTION__);
         return (-1);
     }
@@ -3636,10 +3633,22 @@ xenDaemonGetSchedulerParameters(virDomainPtr domain,
 
     switch (sched_nparam){
         case XEN_SCHED_SEDF_NPARAM:
+            if (*nparams < XEN_SCHED_SEDF_NPARAM) {
+                virXendError(VIR_ERR_INVALID_ARG,
+                             "%s", _("Invalid parameter count"));
+                goto error;
+            }
+
             /* TODO: Implement for Xen/SEDF */
             TODO
             goto error;
         case XEN_SCHED_CRED_NPARAM:
+            if (*nparams < XEN_SCHED_CRED_NPARAM) {
+                virXendError(VIR_ERR_INVALID_ARG,
+                             "%s", _("Invalid parameter count"));
+                goto error;
+            }
+
             /* get cpu_weight/cpu_cap from xend/domain */
             if (sexpr_node(root, "domain/cpu_weight") == NULL) {
                 virXendError(VIR_ERR_INTERNAL_ERROR,