linux-kernel - [PATCH] LoongArch: Flush TLB earlier at initialization

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Date:   Wed, 12 Oct 2022 09:57:07 +0800
From:   Huacai Chen <chenhuacai@...ngson.cn>
To:     Huacai Chen <chenhuacai@...nel.org>
Cc:     loongarch@...ts.linux.dev, Xuefeng Li <lixuefeng@...ngson.cn>,
        Guo Ren <guoren@...nel.org>, Xuerui Wang <kernel@...0n.name>,
        Jiaxun Yang <jiaxun.yang@...goat.com>,
        linux-kernel@...r.kernel.org, Huacai Chen <chenhuacai@...ngson.cn>
Subject: [PATCH] LoongArch: Flush TLB earlier at initialization

Move local_flush_tlb_all() earlier (just after setup_ptwalker() and
before page allocation). This can avoid stale TLB entries misguiding
the later page allocation. Without this patch the second kernel of
kexec/kdump fails to boot SMP.

BTW, move output_pgtable_bits_defines() into tlb_init() since it has
nothing to do with tlb handler setup.

Signed-off-by: Huacai Chen <chenhuacai@...ngson.cn>
---
 arch/loongarch/mm/tlb.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/loongarch/mm/tlb.c b/arch/loongarch/mm/tlb.c
index 9818ce11546b..da3681f131c8 100644
--- a/arch/loongarch/mm/tlb.c
+++ b/arch/loongarch/mm/tlb.c
@@ -258,7 +258,7 @@ extern long exception_handlers[VECSIZE * 128 / sizeof(long)];
 void setup_tlb_handler(int cpu)
 {
 	setup_ptwalker();
-	output_pgtable_bits_defines();
+	local_flush_tlb_all();
 
 	/* The tlb handlers are generated only once */
 	if (cpu == 0) {
@@ -301,6 +301,7 @@ void tlb_init(int cpu)
 	write_csr_pagesize(PS_DEFAULT_SIZE);
 	write_csr_stlbpgsize(PS_DEFAULT_SIZE);
 	write_csr_tlbrefill_pagesize(PS_DEFAULT_SIZE);
+
 	setup_tlb_handler(cpu);
-	local_flush_tlb_all();
+	output_pgtable_bits_defines();
 }
-- 
2.31.1