From 044b8744d65f8571038f85685b3c4b241162977b Mon Sep 17 00:00:00 2001
From: Michal Privoznik <mprivozn@redhat.com>
Date: Tue, 9 Aug 2022 16:16:09 +0200
Subject: [PATCH] qemu: Implement qemuDomainGetStatsCpu fallback for
 qemu:///session
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For domains started under session URI, we don't set up CGroups
(well, how could we since we're not running as root anyways).
Nevertheless, fetching CPU statistics exits early because of
lacking cpuacct controller. But with recent extension to
virProcessGetStatInfo() we can get the values we need from the
proc filesystem. Implement the fallback for the session URI as
some of virt tools rely on cpu.* stats to be reported (virt-top,
virt-manager).

Resolves: https://gitlab.com/libvirt/libvirt/-/issues/353
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1693707
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
---
 src/qemu/qemu_driver.c | 35 +++++++++++++++++++++++++++++++++--
 1 file changed, 33 insertions(+), 2 deletions(-)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index d7283a6e47..c7cca64001 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -17765,6 +17765,30 @@ qemuDomainGetStatsCpuCgroup(virDomainObj *dom,
     return 0;
 }
 
+
+static int
+qemuDomainGetStatsCpuProc(virDomainObj *vm,
+                          virTypedParamList *params)
+{
+    unsigned long long cpuTime = 0;
+    unsigned long long sysTime = 0;
+    unsigned long long userTime = 0;
+
+    if (virProcessGetStatInfo(&cpuTime, &sysTime, &userTime,
+                              NULL, NULL, vm->pid, 0) < 0) {
+        /* ignore error */
+        return 0;
+    }
+
+    if (virTypedParamListAddULLong(params, cpuTime, "cpu.time") < 0 ||
+        virTypedParamListAddULLong(params, userTime, "cpu.user") < 0 ||
+        virTypedParamListAddULLong(params, sysTime, "cpu.system") < 0)
+        return -1;
+
+    return 0;
+}
+
+
 static int
 qemuDomainGetStatsCpuHaltPollTimeFromStats(virDomainObj *dom,
                                            unsigned int privflags,
@@ -17860,8 +17884,15 @@ qemuDomainGetStatsCpu(virQEMUDriver *driver,
                       virTypedParamList *params,
                       unsigned int privflags)
 {
-    if (qemuDomainGetStatsCpuCgroup(dom, params) < 0)
-        return -1;
+    qemuDomainObjPrivate *priv = dom->privateData;
+
+    if (priv->cgroup) {
+        if (qemuDomainGetStatsCpuCgroup(dom, params) < 0)
+            return -1;
+    } else {
+        if (qemuDomainGetStatsCpuProc(dom, params) < 0)
+            return -1;
+    }
 
     if (qemuDomainGetStatsCpuCache(driver, dom, params) < 0)
         return -1;