[libvirt] [PATCH 2/2] qemu: Add range checking for scheduler tunables

[Peter Krempa]

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.
---
 src/qemu/qemu_driver.c | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 4b8b751..3d59594 100644
--- a/src/qemu/qemu_driver.c
+++ b/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 (long long)              1000
+#define QEMU_SCHED_MAX_PERIOD (long long)           1000000
+#define QEMU_SCHED_MIN_QUOTA  (long long)              1000
+#define QEMU_SCHED_MAX_QUOTA  (long long) 18446744073709551
+
 #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,
-- 
1.7.12