qemu: Add range checking for scheduler tunables when changed by API

The quota and period tunables for cpu scheduler accept only a certain
range of values. When changing the live configuration invalid values get
rejected. This check is not performed when changing persistent config.

This patch adds a separate range check, that improves error messages
when changing live config and adds the check for persistent config.
This check is done only when using the API. It is still possible to
specify invalid values in the XML.

src/qemu/qemu_driver.c

@@ -106,6 +106,11 @@
 #define QEMU_NB_TOTAL_CPU_STAT_PARAM 3
 #define QEMU_NB_PER_CPU_STAT_PARAM 2
 
+#define QEMU_SCHED_MIN_PERIOD              1000LL
+#define QEMU_SCHED_MAX_PERIOD           1000000LL
+#define QEMU_SCHED_MIN_QUOTA               1000LL
+#define QEMU_SCHED_MAX_QUOTA  18446744073709551LL
+
 #if HAVE_LINUX_KVM_H
 # include <linux/kvm.h>
 #endif
@@ -7790,6 +7795,15 @@ cleanup:
     return -1;
 }
 
+#define SCHED_RANGE_CHECK(VAR, NAME, MIN, MAX)                              \
+    if (((VAR) > 0 && (VAR) < (MIN)) || (VAR) > (MAX)) {                    \
+        virReportError(VIR_ERR_INVALID_ARG,                                 \
+                       _("value of '%s' is out of range [%lld, %lld]"),     \
+                       NAME, MIN, MAX);                                     \
+        rc = -1;                                                            \
+        goto cleanup;                                                       \
+    }
+
 static int
 qemuSetSchedulerParametersFlags(virDomainPtr dom,
                                 virTypedParameterPtr params,
@@ -7876,6 +7890,9 @@ qemuSetSchedulerParametersFlags(virDomainPtr dom,
                 vmdef->cputune.shares = value_ul;
 
         } else if (STREQ(param->field, VIR_DOMAIN_SCHEDULER_VCPU_PERIOD)) {
+            SCHED_RANGE_CHECK(value_ul, VIR_DOMAIN_SCHEDULER_VCPU_PERIOD,
+                              QEMU_SCHED_MIN_PERIOD, QEMU_SCHED_MAX_PERIOD);
+
             if (flags & VIR_DOMAIN_AFFECT_LIVE && value_ul) {
                 if ((rc = qemuSetVcpusBWLive(vm, group, value_ul, 0)))
                     goto cleanup;
@@ -7887,6 +7904,9 @@ qemuSetSchedulerParametersFlags(virDomainPtr dom,
                 vmdef->cputune.period = params[i].value.ul;
 
         } else if (STREQ(param->field, VIR_DOMAIN_SCHEDULER_VCPU_QUOTA)) {
+            SCHED_RANGE_CHECK(value_l, VIR_DOMAIN_SCHEDULER_VCPU_QUOTA,
+                              QEMU_SCHED_MIN_QUOTA, QEMU_SCHED_MAX_QUOTA);
+
             if (flags & VIR_DOMAIN_AFFECT_LIVE && value_l) {
                 if ((rc = qemuSetVcpusBWLive(vm, group, 0, value_l)))
                     goto cleanup;
@@ -7898,6 +7918,9 @@ qemuSetSchedulerParametersFlags(virDomainPtr dom,
                 vmdef->cputune.quota = value_l;
 
         } else if (STREQ(param->field, VIR_DOMAIN_SCHEDULER_EMULATOR_PERIOD)) {
+            SCHED_RANGE_CHECK(value_ul, VIR_DOMAIN_SCHEDULER_EMULATOR_PERIOD,
+                              QEMU_SCHED_MIN_PERIOD, QEMU_SCHED_MAX_PERIOD);
+
             if (flags & VIR_DOMAIN_AFFECT_LIVE && value_ul) {
                 if ((rc = qemuSetEmulatorBandwidthLive(vm, group, value_ul, 0)))
                     goto cleanup;
@@ -7909,6 +7932,9 @@ qemuSetSchedulerParametersFlags(virDomainPtr dom,
                 vmdef->cputune.emulator_period = value_ul;
 
         } else if (STREQ(param->field, VIR_DOMAIN_SCHEDULER_EMULATOR_QUOTA)) {
+            SCHED_RANGE_CHECK(value_l, VIR_DOMAIN_SCHEDULER_EMULATOR_QUOTA,
+                              QEMU_SCHED_MIN_QUOTA, QEMU_SCHED_MAX_QUOTA);
+
             if (flags & VIR_DOMAIN_AFFECT_LIVE && value_l) {
                 if ((rc = qemuSetEmulatorBandwidthLive(vm, group, 0, value_l)))
                     goto cleanup;
@@ -7944,6 +7970,7 @@ cleanup:
     qemuDriverUnlock(driver);
     return ret;
 }
+#undef SCHED_RANGE_CHECK
 
 static int
 qemuSetSchedulerParameters(virDomainPtr dom,