[PATCH v2 2/6] qemu_driver: Probe capability before calculating dirty page rate

[huangy81@xxxxxxxxxxxxxxx]

From: Hyman Huang(黄勇) <huangy81@xxxxxxxxxxxxxxx>

Probing QEMU_CAPS_CALC_DIRTY_RATE capability in advance
in case of failure when calculating dirty page rate.

Signed-off-by: Hyman Huang(黄勇) <huangy81@xxxxxxxxxxxxxxx>
---
 src/qemu/qemu_driver.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 0a1ba74..0e8e9b1 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -20647,10 +20647,22 @@ qemuDomainStartDirtyRateCalc(virDomainPtr dom,
     virQEMUDriver *driver = dom->conn->privateData;
     virDomainObj *vm = NULL;
     qemuDomainObjPrivate *priv;
+    g_autoptr(virQEMUCaps) qemucaps = NULL;
     int ret = -1;
 
     virCheckFlags(0, -1);
 
+    if (!(qemucaps = virQEMUCapsCacheLookupDefault(driver->qemuCapsCache,
+                                                   NULL, NULL, NULL, NULL,
+                                                   NULL, NULL, NULL)))
+        return -1;
+
+    if (!virQEMUCapsGet(qemucaps, QEMU_CAPS_CALC_DIRTY_RATE)) {
+        virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
+                       _("QEMU does not support calculating dirty page rate"));
+        return -1;
+    }
+
     if (seconds < MIN_DIRTYRATE_CALC_PERIOD ||
         seconds > MAX_DIRTYRATE_CALC_PERIOD) {
         virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
-- 
1.8.3.1