[PATCH v6 01/14] powerpc/64s: Do not re-activate batched TLB flush

Kevin Brodsky
2025-12-15T15:03:43Z

From: Alexander Gordeev <agordeev@linux.ibm.com>

Since commit b9ef323ea168 ("powerpc/64s: Disable preemption in hash
lazy mmu mode") a task can not be preempted while in lazy MMU mode.
Therefore, the batch re-activation code is never called, so remove it.

Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
---
arch/powerpc/include/asm/thread_info.h | 2 --
arch/powerpc/kernel/process.c | 25 -------------------------
2 files changed, 27 deletions(-)

diff --git a/arch/powerpc/include/asm/thread_info.h b/arch/powerpc/include/asm/thread_info.h
index b0f200aba2b3..97f35f9b1a96 100644
--- a/arch/powerpc/include/asm/thread_info.h
+++ b/arch/powerpc/include/asm/thread_info.h
@@ -154,12 +154,10 @@ void arch_setup_new_exec(void);
/* Don't move TLF_NAPPING without adjusting the code in entry_32.S */
#define TLF_NAPPING 0 /* idle thread enabled NAP mode */
#define TLF_SLEEPING 1 /* suspend code enabled SLEEP mode */
-#define TLF_LAZY_MMU 3 /* tlb_batch is active */
#define TLF_RUNLATCH 4 /* Is the runlatch enabled? */

#define _TLF_NAPPING (1 << TLF_NAPPING)
#define _TLF_SLEEPING (1 << TLF_SLEEPING)
-#define _TLF_LAZY_MMU (1 << TLF_LAZY_MMU)
#define _TLF_RUNLATCH (1 << TLF_RUNLATCH)

#ifndef __ASSEMBLER__
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index a45fe147868b..a15d0b619b1f 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1281,9 +1281,6 @@ struct task_struct *__switch_to(struct task_struct *prev,
{
struct thread_struct *new_thread, *old_thread;
struct task_struct *last;
-#ifdef CONFIG_PPC_64S_HASH_MMU
- struct ppc64_tlb_batch *batch;
-#endif

new_thread = &new->thread;
old_thread = &current->thread;
@@ -1291,14 +1288,6 @@ struct task_struct *__switch_to(struct task_struct *prev,
WARN_ON(!irqs_disabled());

#ifdef CONFIG_PPC_64S_HASH_MMU
- batch = this_cpu_ptr(&ppc64_tlb_batch);
- if (batch->active) {
- current_thread_info()->local_flags |= _TLF_LAZY_MMU;
- if (batch->index)
- __flush_tlb_pending(batch);
- batch->active = 0;
- }
-
/*
* On POWER9 the copy-paste buffer can only paste into
* foreign real addresses, so unprivileged processes can not
@@ -1369,20 +1358,6 @@ struct task_struct *__switch_to(struct task_struct *prev,
*/

#ifdef CONFIG_PPC_BOOK3S_64
-#ifdef CONFIG_PPC_64S_HASH_MMU
- /*
- * This applies to a process that was context switched while inside
- * arch_enter_lazy_mmu_mode(), to re-activate the batch that was
- * deactivated above, before _switch(). This will never be the case
- * for new tasks.
- */
- if (current_thread_info()->local_flags & _TLF_LAZY_MMU) {
- current_thread_info()->local_flags &= ~_TLF_LAZY_MMU;
- batch = this_cpu_ptr(&ppc64_tlb_batch);
- batch->active = 1;
- }
-#endif
-
/*
* Math facilities are masked out of the child MSR in copy_thread.
* A new task does not need to restore_math because it will
--
2.51.2