| Message ID | 20180625115352.6889-10-david@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | s390x: TOD refactoring + TCG CPU hotplug support | expand |
On Mon, 25 Jun 2018 13:53:52 +0200 David Hildenbrand <david@redhat.com> wrote: > 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 rif of the ifdef. s/rif/rid/ {Although "we get rif the thing" would be a nice contraction of "rid of" :} > > Signed-off-by: David Hildenbrand <david@redhat.com> > --- > target/s390x/cpu.c | 17 ++++++++++++----- > 1 file changed, 12 insertions(+), 5 deletions(-) > > diff --git a/target/s390x/cpu.c b/target/s390x/cpu.c > index 40d6980229..271c5ce652 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:
On 25.06.2018 13:53, David Hildenbrand wrote: > 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 rif of the ifdef. With the typo fixed: Reviewed-by: Thomas Huth <thuth@redhat.com>
diff --git a/target/s390x/cpu.c b/target/s390x/cpu.c index 40d6980229..271c5ce652 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:
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 rif of the ifdef. Signed-off-by: David Hildenbrand <david@redhat.com> --- target/s390x/cpu.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-)