[PATCH v4 6/8] qemu: Enable SCHED_CORE for helper processes

[Michal Privoznik <mprivozn@xxxxxxxxxx>]

For QEMU_SCHED_CORE_FULL case, all helper processes should be
placed into the same scheduling group as the QEMU process they
serve. It may happen though, that a helper process is started
before QEMU (cold start of a domain). But we have the dummy
process running from which the QEMU process will inherit the
scheduling group, so we can use the dummy process PID as an
argument to virCommandSetRunAmong().

Signed-off-by: Michal Privoznik <mprivozn@xxxxxxxxxx>
Reviewed-by: Daniel P. Berrangé <berrange@xxxxxxxxxx>
---
 src/qemu/qemu_process.c  |  9 +++++++++
 src/qemu/qemu_security.c | 11 +++++++++++
 src/qemu/qemu_virtiofs.c | 11 +++++++++++
 3 files changed, 31 insertions(+)

diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
index 808558227e..22845423ce 100644
--- a/src/qemu/qemu_process.c
+++ b/src/qemu/qemu_process.c
@@ -2848,6 +2848,15 @@ qemuProcessStartManagedPRDaemon(virDomainObj *vm)
      * qemu (so that it shares the same view of the system). */
     virCommandSetPreExecHook(cmd, qemuProcessStartPRDaemonHook, vm);
 
+    if (cfg->schedCore == QEMU_SCHED_CORE_FULL) {
+        pid_t cookie_pid = vm->pid;
+
+        if (cookie_pid <= 0)
+            cookie_pid = priv->schedCoreChildPID;
+
+        virCommandSetRunAmong(cmd, cookie_pid);
+    }
+
     if (virCommandRun(cmd, NULL) < 0)
         goto cleanup;
 
diff --git a/src/qemu/qemu_security.c b/src/qemu/qemu_security.c
index 3be1766764..5b7d5f30c2 100644
--- a/src/qemu/qemu_security.c
+++ b/src/qemu/qemu_security.c
@@ -683,6 +683,9 @@ qemuSecurityCommandRun(virQEMUDriver *driver,
                        int *exitstatus,
                        int *cmdret)
 {
+    g_autoptr(virQEMUDriverConfig) cfg = virQEMUDriverGetConfig(driver);
+    qemuDomainObjPrivate *priv = vm->privateData;
+
     if (virSecurityManagerSetChildProcessLabel(driver->securityManager,
                                                vm->def, cmd) < 0)
         return -1;
@@ -691,6 +694,14 @@ qemuSecurityCommandRun(virQEMUDriver *driver,
         virCommandSetUID(cmd, uid);
     if (gid != (gid_t) -1)
         virCommandSetGID(cmd, gid);
+    if (cfg->schedCore == QEMU_SCHED_CORE_FULL) {
+        pid_t pid = vm->pid;
+
+        if (pid <= 0)
+            pid = priv->schedCoreChildPID;
+
+        virCommandSetRunAmong(cmd, pid);
+    }
 
     if (virSecurityManagerPreFork(driver->securityManager) < 0)
         return -1;
diff --git a/src/qemu/qemu_virtiofs.c b/src/qemu/qemu_virtiofs.c
index a04aa08e39..cd947bebfd 100644
--- a/src/qemu/qemu_virtiofs.c
+++ b/src/qemu/qemu_virtiofs.c
@@ -178,6 +178,7 @@ qemuVirtioFSStart(virQEMUDriver *driver,
                   virDomainFSDef *fs)
 {
     g_autoptr(virQEMUDriverConfig) cfg = virQEMUDriverGetConfig(driver);
+    qemuDomainObjPrivate *priv = vm->privateData;
     g_autoptr(virCommand) cmd = NULL;
     g_autofree char *socket_path = NULL;
     g_autofree char *pidfile = NULL;
@@ -251,6 +252,16 @@ qemuVirtioFSStart(virQEMUDriver *driver,
     virCommandNonblockingFDs(cmd);
     virCommandDaemonize(cmd);
 
+    if (cfg->schedCore == QEMU_SCHED_CORE_FULL) {
+        pid_t cookie_pid = vm->pid;
+
+        if (cookie_pid <= 0)
+            cookie_pid = priv->schedCoreChildPID;
+
+        virCommandSetRunAmong(cmd, cookie_pid);
+    }
+
+
     if (qemuExtDeviceLogCommand(driver, vm, cmd, "virtiofsd") < 0)
         goto error;
 
-- 
2.35.1