powerpc: Bring all threads online prior to migration/hibernation
This patch brings online all threads which are present but not online
prior to migration/hibernation. After migration/hibernation those
threads are taken back offline.
During migration/hibernation all online CPUs must call H_JOIN, this is
required by the hypervisor. Without this patch, threads that are offline
(H_CEDE'd) will not be woken to make the H_JOIN call and the OS will be
deadlocked (all threads either JOIN'd or CEDE'd).
Cc: <stable@kernel.org>
Signed-off-by: Robert Jennings <rcj@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c
index 1fd6e7b..52add6f 100644
--- a/arch/powerpc/kernel/rtas.c
+++ b/arch/powerpc/kernel/rtas.c
@@ -19,6 +19,7 @@
#include <linux/init.h>
#include <linux/capability.h>
#include <linux/delay.h>
+#include <linux/cpu.h>
#include <linux/smp.h>
#include <linux/completion.h>
#include <linux/cpumask.h>
@@ -807,6 +808,95 @@
__rtas_suspend_cpu((struct rtas_suspend_me_data *)info, 1);
}
+enum rtas_cpu_state {
+ DOWN,
+ UP,
+};
+
+#ifndef CONFIG_SMP
+static int rtas_cpu_state_change_mask(enum rtas_cpu_state state,
+ cpumask_var_t cpus)
+{
+ if (!cpumask_empty(cpus)) {
+ cpumask_clear(cpus);
+ return -EINVAL;
+ } else
+ return 0;
+}
+#else
+/* On return cpumask will be altered to indicate CPUs changed.
+ * CPUs with states changed will be set in the mask,
+ * CPUs with status unchanged will be unset in the mask. */
+static int rtas_cpu_state_change_mask(enum rtas_cpu_state state,
+ cpumask_var_t cpus)
+{
+ int cpu;
+ int cpuret = 0;
+ int ret = 0;
+
+ if (cpumask_empty(cpus))
+ return 0;
+
+ for_each_cpu(cpu, cpus) {
+ switch (state) {
+ case DOWN:
+ cpuret = cpu_down(cpu);
+ break;
+ case UP:
+ cpuret = cpu_up(cpu);
+ break;
+ }
+ if (cpuret) {
+ pr_debug("%s: cpu_%s for cpu#%d returned %d.\n",
+ __func__,
+ ((state == UP) ? "up" : "down"),
+ cpu, cpuret);
+ if (!ret)
+ ret = cpuret;
+ if (state == UP) {
+ /* clear bits for unchanged cpus, return */
+ cpumask_shift_right(cpus, cpus, cpu);
+ cpumask_shift_left(cpus, cpus, cpu);
+ break;
+ } else {
+ /* clear bit for unchanged cpu, continue */
+ cpumask_clear_cpu(cpu, cpus);
+ }
+ }
+ }
+
+ return ret;
+}
+#endif
+
+int rtas_online_cpus_mask(cpumask_var_t cpus)
+{
+ int ret;
+
+ ret = rtas_cpu_state_change_mask(UP, cpus);
+
+ if (ret) {
+ cpumask_var_t tmp_mask;
+
+ if (!alloc_cpumask_var(&tmp_mask, GFP_TEMPORARY))
+ return ret;
+
+ /* Use tmp_mask to preserve cpus mask from first failure */
+ cpumask_copy(tmp_mask, cpus);
+ rtas_offline_cpus_mask(tmp_mask);
+ free_cpumask_var(tmp_mask);
+ }
+
+ return ret;
+}
+EXPORT_SYMBOL(rtas_online_cpus_mask);
+
+int rtas_offline_cpus_mask(cpumask_var_t cpus)
+{
+ return rtas_cpu_state_change_mask(DOWN, cpus);
+}
+EXPORT_SYMBOL(rtas_offline_cpus_mask);
+
int rtas_ibm_suspend_me(struct rtas_args *args)
{
long state;
@@ -814,6 +904,8 @@
unsigned long retbuf[PLPAR_HCALL_BUFSIZE];
struct rtas_suspend_me_data data;
DECLARE_COMPLETION_ONSTACK(done);
+ cpumask_var_t offline_mask;
+ int cpuret;
if (!rtas_service_present("ibm,suspend-me"))
return -ENOSYS;
@@ -837,11 +929,24 @@
return 0;
}
+ if (!alloc_cpumask_var(&offline_mask, GFP_TEMPORARY))
+ return -ENOMEM;
+
atomic_set(&data.working, 0);
atomic_set(&data.done, 0);
atomic_set(&data.error, 0);
data.token = rtas_token("ibm,suspend-me");
data.complete = &done;
+
+ /* All present CPUs must be online */
+ cpumask_andnot(offline_mask, cpu_present_mask, cpu_online_mask);
+ cpuret = rtas_online_cpus_mask(offline_mask);
+ if (cpuret) {
+ pr_err("%s: Could not bring present CPUs online.\n", __func__);
+ atomic_set(&data.error, cpuret);
+ goto out;
+ }
+
stop_topology_update();
/* Call function on all CPUs. One of us will make the
@@ -857,6 +962,14 @@
start_topology_update();
+ /* Take down CPUs not online prior to suspend */
+ cpuret = rtas_offline_cpus_mask(offline_mask);
+ if (cpuret)
+ pr_warn("%s: Could not restore CPUs to offline state.\n",
+ __func__);
+
+out:
+ free_cpumask_var(offline_mask);
return atomic_read(&data.error);
}
#else /* CONFIG_PPC_PSERIES */