Subject: [PATCH 5/6] powerpc/64s: remove unnecessary translation cache flushes at boot

From: Nicholas Piggin <[email-masked]>
Date: Tue, 3 Sep 2019 01:29:30 +1000

The various translation structure invalidations performed in early boot
when the MMU is off are not required, because everything is invalidated
immediately before a CPU first enables its MMU (see early_init_mmu
and early_init_mmu_secondary).

Signed-off-by: Nicholas Piggin <[email-masked]>
---
 arch/powerpc/mm/book3s64/hash_utils.c    | 2 +-
 arch/powerpc/mm/book3s64/pgtable.c       | 5 +++++
 arch/powerpc/mm/book3s64/radix_pgtable.c | 8 +-------
 arch/powerpc/platforms/pseries/lpar.c    | 5 -----
 4 files changed, 7 insertions(+), 13 deletions(-)

diff --git a/arch/powerpc/mm/book3s64/hash_utils.c b/arch/powerpc/mm/book3s64/hash_utils.c
index b73d08b54d12..7684a596158b 100644
--- a/arch/powerpc/mm/book3s64/hash_utils.c
+++ b/arch/powerpc/mm/book3s64/hash_utils.c
@@ -825,7 +825,7 @@ static void __init hash_init_partition_table(phys_addr_t hash_table,
 	 * For now, UPRT is 0 and we have no segment table.
 	 */
 	htab_size =  __ilog2(htab_size) - 18;
-	mmu_partition_table_set_entry(0, hash_table | htab_size, 0, true);
+	mmu_partition_table_set_entry(0, hash_table | htab_size, 0, false);
 	pr_info("Partition table %p\n", partition_tb);
 }
 
diff --git a/arch/powerpc/mm/book3s64/pgtable.c b/arch/powerpc/mm/book3s64/pgtable.c
index 6fab9c0bbbaf..351eb78eed55 100644
--- a/arch/powerpc/mm/book3s64/pgtable.c
+++ b/arch/powerpc/mm/book3s64/pgtable.c
@@ -252,6 +252,11 @@ void mmu_partition_table_set_entry(unsigned int lpid, unsigned long dw0,
 		pr_info("PATE registered by ultravisor: dw0 = 0x%lx, dw1 = 0x%lx\n",
 			dw0, dw1);
 	} else if (flush) {
+		/*
+		 * Boot does not need to flush, because MMU is off and each
+		 * CPU does a tlbiel_all() before switching them on, which
+		 * flushes everything.
+		 */
 		flush_partition(lpid, (old & PATB_HR));
 	}
 }
diff --git a/arch/powerpc/mm/book3s64/radix_pgtable.c b/arch/powerpc/mm/book3s64/radix_pgtable.c
index e1e711c4704a..0d1107fb34c1 100644
--- a/arch/powerpc/mm/book3s64/radix_pgtable.c
+++ b/arch/powerpc/mm/book3s64/radix_pgtable.c
@@ -396,13 +396,7 @@ static void __init radix_init_partition_table(void)
 	rts_field = radix__get_tree_size();
 	dw0 = rts_field | __pa(init_mm.pgd) | RADIX_PGD_INDEX_SIZE | PATB_HR;
 	dw1 = __pa(process_tb) | (PRTB_SIZE_SHIFT - 12) | PATB_GR;
-	mmu_partition_table_set_entry(0, dw0, dw1, true);
-
-	asm volatile("ptesync" : : : "memory");
-	asm volatile(PPC_TLBIE_5(%0,%1,2,1,1) : :
-		     "r" (TLBIEL_INVAL_SET_LPID), "r" (0));
-	asm volatile("eieio; tlbsync; ptesync" : : : "memory");
-	trace_tlbie(0, 0, TLBIEL_INVAL_SET_LPID, 0, 2, 1, 1);
+	mmu_partition_table_set_entry(0, dw0, dw1, false);
 
 	pr_info("Initializing Radix MMU\n");
 	pr_info("Partition table %p\n", partition_tb);
diff --git a/arch/powerpc/platforms/pseries/lpar.c b/arch/powerpc/platforms/pseries/lpar.c
index b3205a6c950c..36b846f6e74e 100644
--- a/arch/powerpc/platforms/pseries/lpar.c
+++ b/arch/powerpc/platforms/pseries/lpar.c
@@ -1549,11 +1549,6 @@ void radix_init_pseries(void)
 
 	pseries_lpar_register_process_table(__pa(process_tb),
 						0, PRTB_SIZE_SHIFT - 12);
-	asm volatile("ptesync" : : : "memory");
-	asm volatile(PPC_TLBIE_5(%0,%1,2,1,1) : :
-		     "r" (TLBIEL_INVAL_SET_LPID), "r" (0));
-	asm volatile("eieio; tlbsync; ptesync" : : : "memory");
-	trace_tlbie(0, 0, TLBIEL_INVAL_SET_LPID, 0, 2, 1, 1);
 }
 
 #ifdef CONFIG_PPC_SMLPAR
-- 
2.22.0