[PATCH 1/2] powerpc: Allow nesting of lazy MMU mode

[Matthew Wilcox (Oracle)]

As noted in commit 49147beb0ccb ("x86/xen: allow nesting of same lazy
mode"), we can now nest calls to arch_enter_lazy_mmu_mode().  Use ->active
as a counter instead of a flag and only drain the batch when the counter
hits 0.

Signed-off-by: Matthew Wilcox (Oracle) <willy at infradead.org>
Fixes: bcc6cc832573 ("mm: add default definition of set_ptes()")
---
 arch/powerpc/include/asm/book3s/64/tlbflush-hash.h | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/include/asm/book3s/64/tlbflush-hash.h b/arch/powerpc/include/asm/book3s/64/tlbflush-hash.h
index 146287d9580f..bc845d876ed2 100644
--- a/arch/powerpc/include/asm/book3s/64/tlbflush-hash.h
+++ b/arch/powerpc/include/asm/book3s/64/tlbflush-hash.h
@@ -38,7 +38,7 @@ static inline void arch_enter_lazy_mmu_mode(void)
 	 */
 	preempt_disable();
 	batch = this_cpu_ptr(&ppc64_tlb_batch);
-	batch->active = 1;
+	batch->active++;
 }
 
 static inline void arch_leave_lazy_mmu_mode(void)
@@ -49,9 +49,8 @@ static inline void arch_leave_lazy_mmu_mode(void)
 		return;
 	batch = this_cpu_ptr(&ppc64_tlb_batch);
 
-	if (batch->index)
+	if ((--batch->active == 0) && batch->index)
 		__flush_tlb_pending(batch);
-	batch->active = 0;
 	preempt_enable();
 }
 
-- 
2.40.1