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authorDavid Hildenbrand <david@redhat.com>2018-06-27 15:44:10 +0200
committerCornelia Huck <cohuck@redhat.com>2018-07-02 10:37:38 +0200
commitd66b43c896f89d610f8738169db8e10e63a3a9e6 (patch)
tree0860a2437e7ded2e60731d7202bb12a7f3675ea1 /target
parent7c12f710bad60dc7e509da4e80c77e952ef0490c (diff)
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s390x/tcg: fix CPU hotplug with single-threaded TCG
run_on_cpu() doesn't seem to work reliably until the CPU has been fully created if the single-threaded TCG main loop is already running. Therefore, hotplugging a CPU under single-threaded TCG does currently not work. We should use the direct call instead of going via run_on_cpu(). So let's use run_on_cpu() for KVM only - KVM requires it due to the initial CPU reset ioctl. As a nice side effect, we get rid of the ifdef. Reviewed-by: Thomas Huth <thuth@redhat.com> Signed-off-by: David Hildenbrand <david@redhat.com> Message-Id: <20180627134410.4901-10-david@redhat.com> Signed-off-by: Cornelia Huck <cohuck@redhat.com>
Diffstat (limited to 'target')
-rw-r--r--target/s390x/cpu.c17
1 files changed, 12 insertions, 5 deletions
diff --git a/target/s390x/cpu.c b/target/s390x/cpu.c
index 40d6980..271c5ce 100644
--- a/target/s390x/cpu.c
+++ b/target/s390x/cpu.c
@@ -218,11 +218,18 @@ static void s390_cpu_realizefn(DeviceState *dev, Error **errp)
#endif
s390_cpu_gdb_init(cs);
qemu_init_vcpu(cs);
-#if !defined(CONFIG_USER_ONLY)
- run_on_cpu(cs, s390_do_cpu_full_reset, RUN_ON_CPU_NULL);
-#else
- cpu_reset(cs);
-#endif
+
+ /*
+ * KVM requires the initial CPU reset ioctl to be executed on the target
+ * CPU thread. CPU hotplug under single-threaded TCG will not work with
+ * run_on_cpu(), as run_on_cpu() will not work properly if called while
+ * the main thread is already running but the CPU hasn't been realized.
+ */
+ if (kvm_enabled()) {
+ run_on_cpu(cs, s390_do_cpu_full_reset, RUN_ON_CPU_NULL);
+ } else {
+ cpu_reset(cs);
+ }
scc->parent_realize(dev, &err);
out: