Merge branch 'fixes' into next

There's a non-trivial dependency between some commits we want to put in
next and the KVM prefetch work around that went into fixes. So merge
fixes into next.

1 files changed, 34 insertions, 2 deletions

diff --git a/arch/powerpc/include/asm/mmu_context.h b/arch/powerpc/include/asm/mmu_context.h
index eb749c86dca5..2ab328f0159e 100644
--- a/arch/powerpc/include/asm/mmu_context.h
+++ b/arch/powerpc/include/asm/mmu_context.h
@@ -45,7 +45,7 @@ extern void set_context(unsigned long id, pgd_t *pgd);
 
 #ifdef CONFIG_PPC_BOOK3S_64
 extern void radix__switch_mmu_context(struct mm_struct *prev,
-				     struct mm_struct *next);
+				      struct mm_struct *next);
 static inline void switch_mmu_context(struct mm_struct *prev,
 				      struct mm_struct *next,
 				      struct task_struct *tsk)
@@ -67,6 +67,12 @@ extern void __destroy_context(unsigned long context_id);
 extern void mmu_context_init(void);
 #endif
 
+#if defined(CONFIG_KVM_BOOK3S_HV_POSSIBLE) && defined(CONFIG_PPC_RADIX_MMU)
+extern void radix_kvm_prefetch_workaround(struct mm_struct *mm);
+#else
+static inline void radix_kvm_prefetch_workaround(struct mm_struct *mm) { }
+#endif
+
 extern void switch_cop(struct mm_struct *next);
 extern int use_cop(unsigned long acop, struct mm_struct *mm);
 extern void drop_cop(unsigned long acop, struct mm_struct *mm);
@@ -79,10 +85,32 @@ static inline void switch_mm_irqs_off(struct mm_struct *prev,
 				      struct mm_struct *next,
 				      struct task_struct *tsk)
 {
+	bool new_on_cpu = false;
+
 	/* Mark this context has been used on the new CPU */
-	if (!cpumask_test_cpu(smp_processor_id(), mm_cpumask(next)))
+	if (!cpumask_test_cpu(smp_processor_id(), mm_cpumask(next))) {
 		cpumask_set_cpu(smp_processor_id(), mm_cpumask(next));
 
+		/*
+		 * This full barrier orders the store to the cpumask above vs
+		 * a subsequent operation which allows this CPU to begin loading
+		 * translations for next.
+		 *
+		 * When using the radix MMU that operation is the load of the
+		 * MMU context id, which is then moved to SPRN_PID.
+		 *
+		 * For the hash MMU it is either the first load from slb_cache
+		 * in switch_slb(), and/or the store of paca->mm_ctx_id in
+		 * copy_mm_to_paca().
+		 *
+		 * On the read side the barrier is in pte_xchg(), which orders
+		 * the store to the PTE vs the load of mm_cpumask.
+		 */
+		smp_mb();
+
+		new_on_cpu = true;
+	}
+
 	/* 32-bit keeps track of the current PGDIR in the thread struct */
 #ifdef CONFIG_PPC32
 	tsk->thread.pgdir = next->pgd;
@@ -103,6 +131,10 @@ static inline void switch_mm_irqs_off(struct mm_struct *prev,
 	if (cpu_has_feature(CPU_FTR_ALTIVEC))
 		asm volatile ("dssall");
 #endif /* CONFIG_ALTIVEC */
+
+	if (new_on_cpu)
+		radix_kvm_prefetch_workaround(next);
+
 	/*
 	 * The actual HW switching method differs between the various
 	 * sub architectures. Out of line for now