Merge branch 'topic/paca' into next

[linux-2.6-microblaze.git] / arch / powerpc / platforms / powernv / idle.c

diff --git a/arch/powerpc/platforms/powernv/idle.c b/arch/powerpc/platforms/powernv/idle.c
index 5b2ca71..d9e366b 100644 (file)
--- a/arch/powerpc/platforms/powernv/idle.c
+++ b/arch/powerpc/platforms/powernv/idle.c
@@ -24,6 +24,7 @@
 #include <asm/code-patching.h>
 #include <asm/smp.h>
 #include <asm/runlatch.h>
+#include <asm/dbell.h>
 
 #include "powernv.h"
 #include "subcore.h"
@@ -387,6 +388,82 @@ void power9_idle(void)
        power9_idle_type(pnv_default_stop_val, pnv_default_stop_mask);
 }
 
+#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
+/*
+ * This is used in working around bugs in thread reconfiguration
+ * on POWER9 (at least up to Nimbus DD2.2) relating to transactional
+ * memory and the way that XER[SO] is checkpointed.
+ * This function forces the core into SMT4 in order by asking
+ * all other threads not to stop, and sending a message to any
+ * that are in a stop state.
+ * Must be called with preemption disabled.
+ *
+ * DO NOT call this unless cpu_has_feature(CPU_FTR_P9_TM_XER_SO_BUG) is
+ * true; otherwise this function will hang the system, due to the
+ * optimization in power9_idle_stop.
+ */
+void pnv_power9_force_smt4_catch(void)
+{
+       int cpu, cpu0, thr;
+       int awake_threads = 1;          /* this thread is awake */
+       int poke_threads = 0;
+       int need_awake = threads_per_core;
+
+       cpu = smp_processor_id();
+       cpu0 = cpu & ~(threads_per_core - 1);
+       for (thr = 0; thr < threads_per_core; ++thr) {
+               if (cpu != cpu0 + thr)
+                       atomic_inc(&paca_ptrs[cpu0+thr]->dont_stop);
+       }
+       /* order setting dont_stop vs testing requested_psscr */
+       mb();
+       for (thr = 0; thr < threads_per_core; ++thr) {
+               if (!paca_ptrs[cpu0+thr]->requested_psscr)
+                       ++awake_threads;
+               else
+                       poke_threads |= (1 << thr);
+       }
+
+       /* If at least 3 threads are awake, the core is in SMT4 already */
+       if (awake_threads < need_awake) {
+               /* We have to wake some threads; we'll use msgsnd */
+               for (thr = 0; thr < threads_per_core; ++thr) {
+                       if (poke_threads & (1 << thr)) {
+                               ppc_msgsnd_sync();
+                               ppc_msgsnd(PPC_DBELL_MSGTYPE, 0,
+                                          paca_ptrs[cpu0+thr]->hw_cpu_id);
+                       }
+               }
+               /* now spin until at least 3 threads are awake */
+               do {
+                       for (thr = 0; thr < threads_per_core; ++thr) {
+                               if ((poke_threads & (1 << thr)) &&
+                                   !paca_ptrs[cpu0+thr]->requested_psscr) {
+                                       ++awake_threads;
+                                       poke_threads &= ~(1 << thr);
+                               }
+                       }
+               } while (awake_threads < need_awake);
+       }
+}
+EXPORT_SYMBOL_GPL(pnv_power9_force_smt4_catch);
+
+void pnv_power9_force_smt4_release(void)
+{
+       int cpu, cpu0, thr;
+
+       cpu = smp_processor_id();
+       cpu0 = cpu & ~(threads_per_core - 1);
+
+       /* clear all the dont_stop flags */
+       for (thr = 0; thr < threads_per_core; ++thr) {
+               if (cpu != cpu0 + thr)
+                       atomic_dec(&paca_ptrs[cpu0+thr]->dont_stop);
+       }
+}
+EXPORT_SYMBOL_GPL(pnv_power9_force_smt4_release);
+#endif /* CONFIG_KVM_BOOK3S_HV_POSSIBLE */
+
 #ifdef CONFIG_HOTPLUG_CPU
 static void pnv_program_cpu_hotplug_lpcr(unsigned int cpu, u64 lpcr_val)
 {