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[Qemu-devel] [PATCH v4 03/12] tcg: Prepare safe tb_jmp_cache lookup out
From: |
Sergey Fedorov |
Subject: |
[Qemu-devel] [PATCH v4 03/12] tcg: Prepare safe tb_jmp_cache lookup out of tb_lock |
Date: |
Fri, 15 Jul 2016 20:58:43 +0300 |
From: Sergey Fedorov <address@hidden>
Ensure atomicity of CPU's 'tb_jmp_cache' access for future translation
block lookup out of 'tb_lock'.
Note that this patch does *not* make CPU's TLB invalidation safe if it
is done from some other thread while the CPU is in its execution loop.
Signed-off-by: Sergey Fedorov <address@hidden>
Signed-off-by: Sergey Fedorov <address@hidden>
[AJB: fixed missing atomic set, tweak title]
Signed-off-by: Alex Bennée <address@hidden>
[Sergey Fedorov: removed explicit memory barriers;
removed unnecessary atomic_read();
tweaked commit title and message]
Signed-off-by: Sergey Fedorov <address@hidden>
Reviewed-by: Alex Bennée <address@hidden>
---
Changes in v3:
- explicit memory barriers removed
- memset() on 'tb_jmp_cache' replaced with a loop on atomic_set()
Changes in v2:
- fix spelling s/con't/can't/
- add atomic_read while clearing tb_jmp_cache
- add r-b tags
Changes in v1 (AJB):
- tweak title
- fixed missing set of tb_jmp_cache
---
cpu-exec.c | 4 ++--
translate-all.c | 10 +++++++---
2 files changed, 9 insertions(+), 5 deletions(-)
diff --git a/cpu-exec.c b/cpu-exec.c
index 974de6aa27ee..2fd1875a7317 100644
--- a/cpu-exec.c
+++ b/cpu-exec.c
@@ -315,7 +315,7 @@ static TranslationBlock *tb_find_slow(CPUState *cpu,
found:
/* we add the TB in the virtual pc hash table */
- cpu->tb_jmp_cache[tb_jmp_cache_hash_func(pc)] = tb;
+ atomic_set(&cpu->tb_jmp_cache[tb_jmp_cache_hash_func(pc)], tb);
return tb;
}
@@ -333,7 +333,7 @@ static inline TranslationBlock *tb_find_fast(CPUState *cpu,
is executed. */
cpu_get_tb_cpu_state(env, &pc, &cs_base, &flags);
tb_lock();
- tb = cpu->tb_jmp_cache[tb_jmp_cache_hash_func(pc)];
+ tb = atomic_read(&cpu->tb_jmp_cache[tb_jmp_cache_hash_func(pc)]);
if (unlikely(!tb || tb->pc != pc || tb->cs_base != cs_base ||
tb->flags != flags)) {
tb = tb_find_slow(cpu, pc, cs_base, flags);
diff --git a/translate-all.c b/translate-all.c
index 0d47c1c0cf82..fdf520a86d68 100644
--- a/translate-all.c
+++ b/translate-all.c
@@ -848,7 +848,11 @@ void tb_flush(CPUState *cpu)
tcg_ctx.tb_ctx.nb_tbs = 0;
CPU_FOREACH(cpu) {
- memset(cpu->tb_jmp_cache, 0, sizeof(cpu->tb_jmp_cache));
+ int i;
+
+ for (i = 0; i < TB_JMP_CACHE_SIZE; ++i) {
+ atomic_set(&cpu->tb_jmp_cache[i], NULL);
+ }
cpu->tb_flushed = true;
}
@@ -1007,8 +1011,8 @@ void tb_phys_invalidate(TranslationBlock *tb,
tb_page_addr_t page_addr)
/* remove the TB from the hash list */
h = tb_jmp_cache_hash_func(tb->pc);
CPU_FOREACH(cpu) {
- if (cpu->tb_jmp_cache[h] == tb) {
- cpu->tb_jmp_cache[h] = NULL;
+ if (atomic_read(&cpu->tb_jmp_cache[h]) == tb) {
+ atomic_set(&cpu->tb_jmp_cache[h], NULL);
}
}
--
2.9.1
- [Qemu-devel] [PATCH v4 00/12] Reduce lock contention on TCG hot-path, Sergey Fedorov, 2016/07/15
- [Qemu-devel] [PATCH v4 02/12] tcg: Pass last_tb by value to tb_find_fast(), Sergey Fedorov, 2016/07/15
- [Qemu-devel] [PATCH v4 03/12] tcg: Prepare safe tb_jmp_cache lookup out of tb_lock,
Sergey Fedorov <=
- [Qemu-devel] [PATCH v4 01/12] util/qht: Document memory ordering assumptions, Sergey Fedorov, 2016/07/15
- [Qemu-devel] [PATCH v4 04/12] tcg: Prepare safe access to tb_flushed out of tb_lock, Sergey Fedorov, 2016/07/15
- [Qemu-devel] [PATCH v4 08/12] tcg: set up tb->page_addr before insertion, Sergey Fedorov, 2016/07/15
- [Qemu-devel] [PATCH v4 07/12] tcg: Prepare TB invalidation for lockless TB lookup, Sergey Fedorov, 2016/07/15
- [Qemu-devel] [PATCH v4 05/12] target-i386: Remove redundant HF_SOFTMMU_MASK, Sergey Fedorov, 2016/07/15
- [Qemu-devel] [PATCH v4 06/12] tcg: Introduce tb_mark_invalid() and tb_is_invalid(), Sergey Fedorov, 2016/07/15
- [Qemu-devel] [PATCH v4 09/12] tcg: cpu-exec: remove tb_lock from the hot-path, Sergey Fedorov, 2016/07/15
- [Qemu-devel] [PATCH v4 10/12] tcg: Avoid bouncing tb_lock between tb_gen_code() and tb_add_jump(), Sergey Fedorov, 2016/07/15
- [Qemu-devel] [PATCH v4 12/12] tcg: rename tb_find_physical(), Sergey Fedorov, 2016/07/15
- [Qemu-devel] [PATCH v4 11/12] tcg: Merge tb_find_slow() and tb_find_fast(), Sergey Fedorov, 2016/07/15