From 61b8cef1d42567d3029e0c7180cbd0f16cc4be2d Mon Sep 17 00:00:00 2001 From: "Emilio G. Cota" Date: Tue, 11 Jul 2017 18:47:38 -0400 Subject: qht: require a default comparison function MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit qht_lookup now uses the default cmp function. qht_lookup_custom is defined to retain the old behaviour, that is a cmp function is explicitly provided. qht_insert will gain use of the default cmp in the next patch. Note that we move qht_lookup_custom's @func to be the last argument, which makes the new qht_lookup as simple as possible. Instead of this (i.e. keeping @func 2nd): 0000000000010750 : 10750: 89 d1 mov %edx,%ecx 10752: 48 89 f2 mov %rsi,%rdx 10755: 48 8b 77 08 mov 0x8(%rdi),%rsi 10759: e9 22 ff ff ff jmpq 10680 1075e: 66 90 xchg %ax,%ax We get: 0000000000010740 : 10740: 48 8b 4f 08 mov 0x8(%rdi),%rcx 10744: e9 37 ff ff ff jmpq 10680 10749: 0f 1f 80 00 00 00 00 nopl 0x0(%rax) Reviewed-by: Richard Henderson Reviewed-by: Alex Bennée Signed-off-by: Emilio G. Cota Signed-off-by: Richard Henderson --- accel/tcg/cpu-exec.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'accel/tcg/cpu-exec.c') diff --git a/accel/tcg/cpu-exec.c b/accel/tcg/cpu-exec.c index 4ef95d8dd3..6d6c51b686 100644 --- a/accel/tcg/cpu-exec.c +++ b/accel/tcg/cpu-exec.c @@ -295,7 +295,7 @@ struct tb_desc { uint32_t trace_vcpu_dstate; }; -static bool tb_cmp(const void *p, const void *d) +static bool tb_lookup_cmp(const void *p, const void *d) { const TranslationBlock *tb = p; const struct tb_desc *desc = d; @@ -340,7 +340,7 @@ TranslationBlock *tb_htable_lookup(CPUState *cpu, target_ulong pc, phys_pc = get_page_addr_code(desc.env, pc); desc.phys_page1 = phys_pc & TARGET_PAGE_MASK; h = tb_hash_func(phys_pc, pc, flags, cf_mask, *cpu->trace_dstate); - return qht_lookup(&tb_ctx.htable, tb_cmp, &desc, h); + return qht_lookup_custom(&tb_ctx.htable, &desc, h, tb_lookup_cmp); } void tb_set_jmp_target(TranslationBlock *tb, int n, uintptr_t addr) -- cgit 1.4.1 From be2cdc5e352eb28b4ff631f053a261d91e6af78e Mon Sep 17 00:00:00 2001 From: "Emilio G. Cota" Date: Wed, 26 Jul 2017 16:58:05 -0400 Subject: tcg: track TBs with per-region BST's MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This paves the way for enabling scalable parallel generation of TCG code. Instead of tracking TBs with a single binary search tree (BST), use a BST for each TCG region, protecting it with a lock. This is as scalable as it gets, since each TCG thread operates on a separate region. The core of this change is the introduction of struct tcg_region_tree, which contains a pointer to a GTree and an associated lock to serialize accesses to it. We then allocate an array of tcg_region_tree's, adding the appropriate padding to avoid false sharing based on qemu_dcache_linesize. Given a tc_ptr, we first find the corresponding region_tree. This is done by special-casing the first and last regions first, since they might be of size != region.size; otherwise we just divide the offset by region.stride. I was worried about this division (several dozen cycles of latency), but profiling shows that this is not a fast path. Note that region.stride is not required to be a power of two; it is only required to be a multiple of the host's page size. Note that with this design we can also provide consistent snapshots about all region trees at once; for instance, tcg_tb_foreach acquires/releases all region_tree locks before/after iterating over them. For this reason we now drop tb_lock in dump_exec_info(). As an alternative I considered implementing a concurrent BST, but this can be tricky to get right, offers no consistent snapshots of the BST, and performance and scalability-wise I don't think it could ever beat having separate GTrees, given that our workload is insert-mostly (all concurrent BST designs I've seen focus, understandably, on making lookups fast, which comes at the expense of convoluted, non-wait-free insertions/removals). Reviewed-by: Richard Henderson Reviewed-by: Alex Bennée Signed-off-by: Emilio G. Cota Signed-off-by: Richard Henderson --- accel/tcg/cpu-exec.c | 2 +- accel/tcg/translate-all.c | 101 ++++-------------------- include/exec/exec-all.h | 1 - include/exec/tb-context.h | 1 - tcg/tcg.c | 191 ++++++++++++++++++++++++++++++++++++++++++++++ tcg/tcg.h | 6 ++ 6 files changed, 213 insertions(+), 89 deletions(-) (limited to 'accel/tcg/cpu-exec.c') diff --git a/accel/tcg/cpu-exec.c b/accel/tcg/cpu-exec.c index 6d6c51b686..7570c59f09 100644 --- a/accel/tcg/cpu-exec.c +++ b/accel/tcg/cpu-exec.c @@ -224,7 +224,7 @@ static void cpu_exec_nocache(CPUState *cpu, int max_cycles, tb_lock(); tb_phys_invalidate(tb, -1); - tb_remove(tb); + tcg_tb_remove(tb); tb_unlock(); } #endif diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c index 1695f8c352..ef841c82cc 100644 --- a/accel/tcg/translate-all.c +++ b/accel/tcg/translate-all.c @@ -205,8 +205,6 @@ void tb_lock_reset(void) } } -static TranslationBlock *tb_find_pc(uintptr_t tc_ptr); - void cpu_gen_init(void) { tcg_context_init(&tcg_init_ctx); @@ -375,13 +373,13 @@ bool cpu_restore_state(CPUState *cpu, uintptr_t host_pc, bool will_exit) if (check_offset < tcg_init_ctx.code_gen_buffer_size) { tb_lock(); - tb = tb_find_pc(host_pc); + tb = tcg_tb_lookup(host_pc); if (tb) { cpu_restore_state_from_tb(cpu, tb, host_pc, will_exit); if (tb->cflags & CF_NOCACHE) { /* one-shot translation, invalidate it immediately */ tb_phys_invalidate(tb, -1); - tb_remove(tb); + tcg_tb_remove(tb); } r = true; } @@ -728,48 +726,6 @@ static inline void *alloc_code_gen_buffer(void) } #endif /* USE_STATIC_CODE_GEN_BUFFER, WIN32, POSIX */ -/* compare a pointer @ptr and a tb_tc @s */ -static int ptr_cmp_tb_tc(const void *ptr, const struct tb_tc *s) -{ - if (ptr >= s->ptr + s->size) { - return 1; - } else if (ptr < s->ptr) { - return -1; - } - return 0; -} - -static gint tb_tc_cmp(gconstpointer ap, gconstpointer bp) -{ - const struct tb_tc *a = ap; - const struct tb_tc *b = bp; - - /* - * When both sizes are set, we know this isn't a lookup. - * This is the most likely case: every TB must be inserted; lookups - * are a lot less frequent. - */ - if (likely(a->size && b->size)) { - if (a->ptr > b->ptr) { - return 1; - } else if (a->ptr < b->ptr) { - return -1; - } - /* a->ptr == b->ptr should happen only on deletions */ - g_assert(a->size == b->size); - return 0; - } - /* - * All lookups have either .size field set to 0. - * From the glib sources we see that @ap is always the lookup key. However - * the docs provide no guarantee, so we just mark this case as likely. - */ - if (likely(a->size == 0)) { - return ptr_cmp_tb_tc(a->ptr, b); - } - return ptr_cmp_tb_tc(b->ptr, a); -} - static inline void code_gen_alloc(size_t tb_size) { tcg_ctx->code_gen_buffer_size = size_code_gen_buffer(tb_size); @@ -778,7 +734,6 @@ static inline void code_gen_alloc(size_t tb_size) fprintf(stderr, "Could not allocate dynamic translator buffer\n"); exit(1); } - tb_ctx.tb_tree = g_tree_new(tb_tc_cmp); qemu_mutex_init(&tb_ctx.tb_lock); } @@ -839,14 +794,6 @@ static TranslationBlock *tb_alloc(target_ulong pc) return tb; } -/* Called with tb_lock held. */ -void tb_remove(TranslationBlock *tb) -{ - assert_tb_locked(); - - g_tree_remove(tb_ctx.tb_tree, &tb->tc); -} - static inline void invalidate_page_bitmap(PageDesc *p) { #ifdef CONFIG_SOFTMMU @@ -911,10 +858,10 @@ static void do_tb_flush(CPUState *cpu, run_on_cpu_data tb_flush_count) } if (DEBUG_TB_FLUSH_GATE) { - size_t nb_tbs = g_tree_nnodes(tb_ctx.tb_tree); + size_t nb_tbs = tcg_nb_tbs(); size_t host_size = 0; - g_tree_foreach(tb_ctx.tb_tree, tb_host_size_iter, &host_size); + tcg_tb_foreach(tb_host_size_iter, &host_size); printf("qemu: flush code_size=%zu nb_tbs=%zu avg_tb_size=%zu\n", tcg_code_size(), nb_tbs, nb_tbs > 0 ? host_size / nb_tbs : 0); } @@ -923,10 +870,6 @@ static void do_tb_flush(CPUState *cpu, run_on_cpu_data tb_flush_count) cpu_tb_jmp_cache_clear(cpu); } - /* Increment the refcount first so that destroy acts as a reset */ - g_tree_ref(tb_ctx.tb_tree); - g_tree_destroy(tb_ctx.tb_tree); - qht_reset_size(&tb_ctx.htable, CODE_GEN_HTABLE_SIZE); page_flush_tb(); @@ -1406,7 +1349,7 @@ TranslationBlock *tb_gen_code(CPUState *cpu, * through the physical hash table and physical page list. */ tb_link_page(tb, phys_pc, phys_page2); - g_tree_insert(tb_ctx.tb_tree, &tb->tc, tb); + tcg_tb_insert(tb); return tb; } @@ -1510,7 +1453,7 @@ void tb_invalidate_phys_page_range(tb_page_addr_t start, tb_page_addr_t end, current_tb = NULL; if (cpu->mem_io_pc) { /* now we have a real cpu fault */ - current_tb = tb_find_pc(cpu->mem_io_pc); + current_tb = tcg_tb_lookup(cpu->mem_io_pc); } } if (current_tb == tb && @@ -1627,7 +1570,7 @@ static bool tb_invalidate_phys_page(tb_page_addr_t addr, uintptr_t pc) tb = p->first_tb; #ifdef TARGET_HAS_PRECISE_SMC if (tb && pc != 0) { - current_tb = tb_find_pc(pc); + current_tb = tcg_tb_lookup(pc); } if (cpu != NULL) { env = cpu->env_ptr; @@ -1670,18 +1613,6 @@ static bool tb_invalidate_phys_page(tb_page_addr_t addr, uintptr_t pc) } #endif -/* - * Find the TB 'tb' such that - * tb->tc.ptr <= tc_ptr < tb->tc.ptr + tb->tc.size - * Return NULL if not found. - */ -static TranslationBlock *tb_find_pc(uintptr_t tc_ptr) -{ - struct tb_tc s = { .ptr = (void *)tc_ptr }; - - return g_tree_lookup(tb_ctx.tb_tree, &s); -} - #if !defined(CONFIG_USER_ONLY) void tb_invalidate_phys_addr(AddressSpace *as, hwaddr addr, MemTxAttrs attrs) { @@ -1709,7 +1640,7 @@ void tb_check_watchpoint(CPUState *cpu) { TranslationBlock *tb; - tb = tb_find_pc(cpu->mem_io_pc); + tb = tcg_tb_lookup(cpu->mem_io_pc); if (tb) { /* We can use retranslation to find the PC. */ cpu_restore_state_from_tb(cpu, tb, cpu->mem_io_pc, true); @@ -1743,7 +1674,7 @@ void cpu_io_recompile(CPUState *cpu, uintptr_t retaddr) uint32_t n; tb_lock(); - tb = tb_find_pc(retaddr); + tb = tcg_tb_lookup(retaddr); if (!tb) { cpu_abort(cpu, "cpu_io_recompile: could not find TB for pc=%p", (void *)retaddr); @@ -1782,7 +1713,7 @@ void cpu_io_recompile(CPUState *cpu, uintptr_t retaddr) * cpu_exec_nocache() */ tb_phys_invalidate(tb->orig_tb, -1); } - tb_remove(tb); + tcg_tb_remove(tb); } /* TODO: If env->pc != tb->pc (i.e. the faulting instruction was not @@ -1853,6 +1784,7 @@ static void print_qht_statistics(FILE *f, fprintf_function cpu_fprintf, } struct tb_tree_stats { + size_t nb_tbs; size_t host_size; size_t target_size; size_t max_target_size; @@ -1866,6 +1798,7 @@ static gboolean tb_tree_stats_iter(gpointer key, gpointer value, gpointer data) const TranslationBlock *tb = value; struct tb_tree_stats *tst = data; + tst->nb_tbs++; tst->host_size += tb->tc.size; tst->target_size += tb->size; if (tb->size > tst->max_target_size) { @@ -1889,10 +1822,8 @@ void dump_exec_info(FILE *f, fprintf_function cpu_fprintf) struct qht_stats hst; size_t nb_tbs; - tb_lock(); - - nb_tbs = g_tree_nnodes(tb_ctx.tb_tree); - g_tree_foreach(tb_ctx.tb_tree, tb_tree_stats_iter, &tst); + tcg_tb_foreach(tb_tree_stats_iter, &tst); + nb_tbs = tst.nb_tbs; /* XXX: avoid using doubles ? */ cpu_fprintf(f, "Translation buffer state:\n"); /* @@ -1927,8 +1858,6 @@ void dump_exec_info(FILE *f, fprintf_function cpu_fprintf) cpu_fprintf(f, "TB invalidate count %d\n", tb_ctx.tb_phys_invalidate_count); cpu_fprintf(f, "TLB flush count %zu\n", tlb_flush_count()); tcg_dump_info(f, cpu_fprintf); - - tb_unlock(); } void dump_opcount_info(FILE *f, fprintf_function cpu_fprintf) @@ -2196,7 +2125,7 @@ int page_unprotect(target_ulong address, uintptr_t pc) * set the page to PAGE_WRITE and did the TB invalidate for us. */ #ifdef TARGET_HAS_PRECISE_SMC - TranslationBlock *current_tb = tb_find_pc(pc); + TranslationBlock *current_tb = tcg_tb_lookup(pc); if (current_tb) { current_tb_invalidated = tb_cflags(current_tb) & CF_INVALID; } diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h index 8bbea787a9..8d4306ac25 100644 --- a/include/exec/exec-all.h +++ b/include/exec/exec-all.h @@ -405,7 +405,6 @@ static inline uint32_t curr_cflags(void) | (use_icount ? CF_USE_ICOUNT : 0); } -void tb_remove(TranslationBlock *tb); void tb_flush(CPUState *cpu); void tb_phys_invalidate(TranslationBlock *tb, tb_page_addr_t page_addr); TranslationBlock *tb_htable_lookup(CPUState *cpu, target_ulong pc, diff --git a/include/exec/tb-context.h b/include/exec/tb-context.h index 1d41202485..d8472c88fb 100644 --- a/include/exec/tb-context.h +++ b/include/exec/tb-context.h @@ -31,7 +31,6 @@ typedef struct TBContext TBContext; struct TBContext { - GTree *tb_tree; struct qht htable; /* any access to the tbs or the page table must use this lock */ QemuMutex tb_lock; diff --git a/tcg/tcg.c b/tcg/tcg.c index 6eeebe0624..62e3391020 100644 --- a/tcg/tcg.c +++ b/tcg/tcg.c @@ -135,6 +135,12 @@ static TCGContext **tcg_ctxs; static unsigned int n_tcg_ctxs; TCGv_env cpu_env = 0; +struct tcg_region_tree { + QemuMutex lock; + GTree *tree; + /* padding to avoid false sharing is computed at run-time */ +}; + /* * We divide code_gen_buffer into equally-sized "regions" that TCG threads * dynamically allocate from as demand dictates. Given appropriate region @@ -158,6 +164,13 @@ struct tcg_region_state { }; static struct tcg_region_state region; +/* + * This is an array of struct tcg_region_tree's, with padding. + * We use void * to simplify the computation of region_trees[i]; each + * struct is found every tree_size bytes. + */ +static void *region_trees; +static size_t tree_size; static TCGRegSet tcg_target_available_regs[TCG_TYPE_COUNT]; static TCGRegSet tcg_target_call_clobber_regs; @@ -295,6 +308,180 @@ TCGLabel *gen_new_label(void) #include "tcg-target.inc.c" +/* compare a pointer @ptr and a tb_tc @s */ +static int ptr_cmp_tb_tc(const void *ptr, const struct tb_tc *s) +{ + if (ptr >= s->ptr + s->size) { + return 1; + } else if (ptr < s->ptr) { + return -1; + } + return 0; +} + +static gint tb_tc_cmp(gconstpointer ap, gconstpointer bp) +{ + const struct tb_tc *a = ap; + const struct tb_tc *b = bp; + + /* + * When both sizes are set, we know this isn't a lookup. + * This is the most likely case: every TB must be inserted; lookups + * are a lot less frequent. + */ + if (likely(a->size && b->size)) { + if (a->ptr > b->ptr) { + return 1; + } else if (a->ptr < b->ptr) { + return -1; + } + /* a->ptr == b->ptr should happen only on deletions */ + g_assert(a->size == b->size); + return 0; + } + /* + * All lookups have either .size field set to 0. + * From the glib sources we see that @ap is always the lookup key. However + * the docs provide no guarantee, so we just mark this case as likely. + */ + if (likely(a->size == 0)) { + return ptr_cmp_tb_tc(a->ptr, b); + } + return ptr_cmp_tb_tc(b->ptr, a); +} + +static void tcg_region_trees_init(void) +{ + size_t i; + + tree_size = ROUND_UP(sizeof(struct tcg_region_tree), qemu_dcache_linesize); + region_trees = qemu_memalign(qemu_dcache_linesize, region.n * tree_size); + for (i = 0; i < region.n; i++) { + struct tcg_region_tree *rt = region_trees + i * tree_size; + + qemu_mutex_init(&rt->lock); + rt->tree = g_tree_new(tb_tc_cmp); + } +} + +static struct tcg_region_tree *tc_ptr_to_region_tree(void *p) +{ + size_t region_idx; + + if (p < region.start_aligned) { + region_idx = 0; + } else { + ptrdiff_t offset = p - region.start_aligned; + + if (offset > region.stride * (region.n - 1)) { + region_idx = region.n - 1; + } else { + region_idx = offset / region.stride; + } + } + return region_trees + region_idx * tree_size; +} + +void tcg_tb_insert(TranslationBlock *tb) +{ + struct tcg_region_tree *rt = tc_ptr_to_region_tree(tb->tc.ptr); + + qemu_mutex_lock(&rt->lock); + g_tree_insert(rt->tree, &tb->tc, tb); + qemu_mutex_unlock(&rt->lock); +} + +void tcg_tb_remove(TranslationBlock *tb) +{ + struct tcg_region_tree *rt = tc_ptr_to_region_tree(tb->tc.ptr); + + qemu_mutex_lock(&rt->lock); + g_tree_remove(rt->tree, &tb->tc); + qemu_mutex_unlock(&rt->lock); +} + +/* + * Find the TB 'tb' such that + * tb->tc.ptr <= tc_ptr < tb->tc.ptr + tb->tc.size + * Return NULL if not found. + */ +TranslationBlock *tcg_tb_lookup(uintptr_t tc_ptr) +{ + struct tcg_region_tree *rt = tc_ptr_to_region_tree((void *)tc_ptr); + TranslationBlock *tb; + struct tb_tc s = { .ptr = (void *)tc_ptr }; + + qemu_mutex_lock(&rt->lock); + tb = g_tree_lookup(rt->tree, &s); + qemu_mutex_unlock(&rt->lock); + return tb; +} + +static void tcg_region_tree_lock_all(void) +{ + size_t i; + + for (i = 0; i < region.n; i++) { + struct tcg_region_tree *rt = region_trees + i * tree_size; + + qemu_mutex_lock(&rt->lock); + } +} + +static void tcg_region_tree_unlock_all(void) +{ + size_t i; + + for (i = 0; i < region.n; i++) { + struct tcg_region_tree *rt = region_trees + i * tree_size; + + qemu_mutex_unlock(&rt->lock); + } +} + +void tcg_tb_foreach(GTraverseFunc func, gpointer user_data) +{ + size_t i; + + tcg_region_tree_lock_all(); + for (i = 0; i < region.n; i++) { + struct tcg_region_tree *rt = region_trees + i * tree_size; + + g_tree_foreach(rt->tree, func, user_data); + } + tcg_region_tree_unlock_all(); +} + +size_t tcg_nb_tbs(void) +{ + size_t nb_tbs = 0; + size_t i; + + tcg_region_tree_lock_all(); + for (i = 0; i < region.n; i++) { + struct tcg_region_tree *rt = region_trees + i * tree_size; + + nb_tbs += g_tree_nnodes(rt->tree); + } + tcg_region_tree_unlock_all(); + return nb_tbs; +} + +static void tcg_region_tree_reset_all(void) +{ + size_t i; + + tcg_region_tree_lock_all(); + for (i = 0; i < region.n; i++) { + struct tcg_region_tree *rt = region_trees + i * tree_size; + + /* Increment the refcount first so that destroy acts as a reset */ + g_tree_ref(rt->tree); + g_tree_destroy(rt->tree); + } + tcg_region_tree_unlock_all(); +} + static void tcg_region_bounds(size_t curr_region, void **pstart, void **pend) { void *start, *end; @@ -380,6 +567,8 @@ void tcg_region_reset_all(void) g_assert(!err); } qemu_mutex_unlock(®ion.lock); + + tcg_region_tree_reset_all(); } #ifdef CONFIG_USER_ONLY @@ -496,6 +685,8 @@ void tcg_region_init(void) g_assert(!rc); } + tcg_region_trees_init(); + /* In user-mode we support only one ctx, so do the initial allocation now */ #ifdef CONFIG_USER_ONLY { diff --git a/tcg/tcg.h b/tcg/tcg.h index 509f4d65d2..1e6df1906f 100644 --- a/tcg/tcg.h +++ b/tcg/tcg.h @@ -866,6 +866,12 @@ void tcg_region_reset_all(void); size_t tcg_code_size(void); size_t tcg_code_capacity(void); +void tcg_tb_insert(TranslationBlock *tb); +void tcg_tb_remove(TranslationBlock *tb); +TranslationBlock *tcg_tb_lookup(uintptr_t tc_ptr); +void tcg_tb_foreach(GTraverseFunc func, gpointer user_data); +size_t tcg_nb_tbs(void); + /* user-mode: Called with tb_lock held. */ static inline void *tcg_malloc(int size) { -- cgit 1.4.1 From faa9372c07d062eb01f9da72e3f6c0f32efffca7 Mon Sep 17 00:00:00 2001 From: "Emilio G. Cota" Date: Thu, 22 Feb 2018 20:50:29 -0500 Subject: translate-all: introduce assert_no_pages_locked The appended adds assertions to make sure we do not longjmp with page locks held. Note that user-mode has nothing to check, since page_locks are !user-mode only. Reviewed-by: Richard Henderson Signed-off-by: Emilio G. Cota Signed-off-by: Richard Henderson --- accel/tcg/cpu-exec.c | 1 + accel/tcg/translate-all.c | 7 +++++++ include/exec/exec-all.h | 8 ++++++++ 3 files changed, 16 insertions(+) (limited to 'accel/tcg/cpu-exec.c') diff --git a/accel/tcg/cpu-exec.c b/accel/tcg/cpu-exec.c index 7570c59f09..d75c35380a 100644 --- a/accel/tcg/cpu-exec.c +++ b/accel/tcg/cpu-exec.c @@ -273,6 +273,7 @@ void cpu_exec_step_atomic(CPUState *cpu) tcg_debug_assert(!have_mmap_lock()); #endif tb_lock_reset(); + assert_no_pages_locked(); } if (in_exclusive_region) { diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c index 8b378586f4..c75298d08a 100644 --- a/accel/tcg/translate-all.c +++ b/accel/tcg/translate-all.c @@ -658,6 +658,12 @@ do_assert_page_locked(const PageDesc *pd, const char *file, int line) #define assert_page_locked(pd) do_assert_page_locked(pd, __FILE__, __LINE__) +void assert_no_pages_locked(void) +{ + ht_pages_locked_debug_init(); + g_assert(g_hash_table_size(ht_pages_locked_debug) == 0); +} + #else /* !CONFIG_DEBUG_TCG */ #define assert_page_locked(pd) @@ -829,6 +835,7 @@ page_collection_lock(tb_page_addr_t start, tb_page_addr_t end) set->tree = g_tree_new_full(tb_page_addr_cmp, NULL, NULL, page_entry_destroy); set->max = NULL; + assert_no_pages_locked(); retry: g_tree_foreach(set->tree, page_entry_lock, NULL); diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h index 8d92e3cea9..4f07a17052 100644 --- a/include/exec/exec-all.h +++ b/include/exec/exec-all.h @@ -435,6 +435,14 @@ void tb_lock(void); void tb_unlock(void); void tb_lock_reset(void); +#if !defined(CONFIG_USER_ONLY) && defined(CONFIG_DEBUG_TCG) +void assert_no_pages_locked(void); +#else +static inline void assert_no_pages_locked(void) +{ +} +#endif + #if !defined(CONFIG_USER_ONLY) /** -- cgit 1.4.1 From 95590e24af11236ef334f6bc3e2b71404a790ddb Mon Sep 17 00:00:00 2001 From: "Emilio G. Cota" Date: Tue, 1 Aug 2017 15:40:16 -0400 Subject: translate-all: discard TB when tb_link_page returns an existing matching TB Use the recently-gained QHT feature of returning the matching TB if it already exists. This allows us to get rid of the lookup we perform right after acquiring tb_lock. Suggested-by: Richard Henderson Reviewed-by: Richard Henderson Signed-off-by: Emilio G. Cota Signed-off-by: Richard Henderson --- accel/tcg/cpu-exec.c | 14 ++---------- accel/tcg/translate-all.c | 50 +++++++++++++++++++++++++++++++++-------- docs/devel/multi-thread-tcg.txt | 3 +++ 3 files changed, 46 insertions(+), 21 deletions(-) (limited to 'accel/tcg/cpu-exec.c') diff --git a/accel/tcg/cpu-exec.c b/accel/tcg/cpu-exec.c index d75c35380a..45f6ebc65e 100644 --- a/accel/tcg/cpu-exec.c +++ b/accel/tcg/cpu-exec.c @@ -245,10 +245,7 @@ void cpu_exec_step_atomic(CPUState *cpu) if (tb == NULL) { mmap_lock(); tb_lock(); - tb = tb_htable_lookup(cpu, pc, cs_base, flags, cf_mask); - if (likely(tb == NULL)) { - tb = tb_gen_code(cpu, pc, cs_base, flags, cflags); - } + tb = tb_gen_code(cpu, pc, cs_base, flags, cflags); tb_unlock(); mmap_unlock(); } @@ -398,14 +395,7 @@ static inline TranslationBlock *tb_find(CPUState *cpu, tb_lock(); acquired_tb_lock = true; - /* There's a chance that our desired tb has been translated while - * taking the locks so we check again inside the lock. - */ - tb = tb_htable_lookup(cpu, pc, cs_base, flags, cf_mask); - if (likely(tb == NULL)) { - /* if no translated code available, then translate it now */ - tb = tb_gen_code(cpu, pc, cs_base, flags, cf_mask); - } + tb = tb_gen_code(cpu, pc, cs_base, flags, cf_mask); mmap_unlock(); /* We add the TB in the virtual pc hash table for the fast lookup */ diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c index c75298d08a..3f977532bf 100644 --- a/accel/tcg/translate-all.c +++ b/accel/tcg/translate-all.c @@ -1581,18 +1581,30 @@ static inline void tb_page_add(PageDesc *p, TranslationBlock *tb, * (-1) to indicate that only one page contains the TB. * * Called with mmap_lock held for user-mode emulation. + * + * Returns a pointer @tb, or a pointer to an existing TB that matches @tb. + * Note that in !user-mode, another thread might have already added a TB + * for the same block of guest code that @tb corresponds to. In that case, + * the caller should discard the original @tb, and use instead the returned TB. */ -static void tb_link_page(TranslationBlock *tb, tb_page_addr_t phys_pc, - tb_page_addr_t phys_page2) +static TranslationBlock * +tb_link_page(TranslationBlock *tb, tb_page_addr_t phys_pc, + tb_page_addr_t phys_page2) { PageDesc *p; PageDesc *p2 = NULL; + void *existing_tb = NULL; uint32_t h; assert_memory_lock(); /* * Add the TB to the page list, acquiring first the pages's locks. + * We keep the locks held until after inserting the TB in the hash table, + * so that if the insertion fails we know for sure that the TBs are still + * in the page descriptors. + * Note that inserting into the hash table first isn't an option, since + * we can only insert TBs that are fully initialized. */ page_lock_pair(&p, phys_pc, &p2, phys_page2, 1); tb_page_add(p, tb, 0, phys_pc & TARGET_PAGE_MASK); @@ -1602,21 +1614,33 @@ static void tb_link_page(TranslationBlock *tb, tb_page_addr_t phys_pc, tb->page_addr[1] = -1; } + /* add in the hash table */ + h = tb_hash_func(phys_pc, tb->pc, tb->flags, tb->cflags & CF_HASH_MASK, + tb->trace_vcpu_dstate); + qht_insert(&tb_ctx.htable, tb, h, &existing_tb); + + /* remove TB from the page(s) if we couldn't insert it */ + if (unlikely(existing_tb)) { + tb_page_remove(p, tb); + invalidate_page_bitmap(p); + if (p2) { + tb_page_remove(p2, tb); + invalidate_page_bitmap(p2); + } + tb = existing_tb; + } + if (p2) { page_unlock(p2); } page_unlock(p); - /* add in the hash table */ - h = tb_hash_func(phys_pc, tb->pc, tb->flags, tb->cflags & CF_HASH_MASK, - tb->trace_vcpu_dstate); - qht_insert(&tb_ctx.htable, tb, h, NULL); - #ifdef CONFIG_USER_ONLY if (DEBUG_TB_CHECK_GATE) { tb_page_check(); } #endif + return tb; } /* Called with mmap_lock held for user mode emulation. */ @@ -1625,7 +1649,7 @@ TranslationBlock *tb_gen_code(CPUState *cpu, uint32_t flags, int cflags) { CPUArchState *env = cpu->env_ptr; - TranslationBlock *tb; + TranslationBlock *tb, *existing_tb; tb_page_addr_t phys_pc, phys_page2; target_ulong virt_page2; tcg_insn_unit *gen_code_buf; @@ -1773,7 +1797,15 @@ TranslationBlock *tb_gen_code(CPUState *cpu, * memory barrier is required before tb_link_page() makes the TB visible * through the physical hash table and physical page list. */ - tb_link_page(tb, phys_pc, phys_page2); + existing_tb = tb_link_page(tb, phys_pc, phys_page2); + /* if the TB already exists, discard what we just translated */ + if (unlikely(existing_tb != tb)) { + uintptr_t orig_aligned = (uintptr_t)gen_code_buf; + + orig_aligned -= ROUND_UP(sizeof(*tb), qemu_icache_linesize); + atomic_set(&tcg_ctx->code_gen_ptr, (void *)orig_aligned); + return existing_tb; + } tcg_tb_insert(tb); return tb; } diff --git a/docs/devel/multi-thread-tcg.txt b/docs/devel/multi-thread-tcg.txt index faf8918b23..faf09c6069 100644 --- a/docs/devel/multi-thread-tcg.txt +++ b/docs/devel/multi-thread-tcg.txt @@ -140,6 +140,9 @@ to atomically insert new elements. The lookup caches are updated atomically and the lookup hash uses QHT which is designed for concurrent safe lookup. +Parallel code generation is supported. QHT is used at insertion time +as the synchronization point across threads, thereby ensuring that we only +keep track of a single TranslationBlock for each guest code block. Memory maps and TLBs -------------------- -- cgit 1.4.1 From 194125e3ebd553acb02aaf3797a4f0387493fe94 Mon Sep 17 00:00:00 2001 From: "Emilio G. Cota" Date: Wed, 2 Aug 2017 20:34:06 -0400 Subject: translate-all: protect TB jumps with a per-destination-TB lock MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This applies to both user-mode and !user-mode emulation. Instead of relying on a global lock, protect the list of incoming jumps with tb->jmp_lock. This lock also protects tb->cflags, so update all tb->cflags readers outside tb->jmp_lock to use atomic reads via tb_cflags(). In order to find the destination TB (and therefore its jmp_lock) from the origin TB, we introduce tb->jmp_dest[]. I considered not using a linked list of jumps, which simplifies code and makes the struct smaller. However, it unnecessarily increases memory usage, which results in a performance decrease. See for instance these numbers booting+shutting down debian-arm: Time (s) Rel. err (%) Abs. err (s) Rel. slowdown (%) ------------------------------------------------------------------------------ before 20.88 0.74 0.154512 0. after 20.81 0.38 0.079078 -0.33524904 GTree 21.02 0.28 0.058856 0.67049808 GHashTable + xxhash 21.63 1.08 0.233604 3.5919540 Using a hash table or a binary tree to keep track of the jumps doesn't really pay off, not only due to the increased memory usage, but also because most TBs have only 0 or 1 jumps to them. The maximum number of jumps when booting debian-arm that I measured is 35, but as we can see in the histogram below a TB with that many incoming jumps is extremely rare; the average TB has 0.80 incoming jumps. n_jumps: 379208; avg jumps/tb: 0.801099 dist: [0.0,1.0)|▄█▁▁▁▁▁▁▁▁▁▁▁ ▁▁▁▁▁▁ ▁▁▁ ▁▁▁ ▁|[34.0,35.0] Reviewed-by: Richard Henderson Signed-off-by: Emilio G. Cota Signed-off-by: Richard Henderson --- accel/tcg/cpu-exec.c | 41 +++++++++----- accel/tcg/translate-all.c | 118 ++++++++++++++++++++++++---------------- docs/devel/multi-thread-tcg.txt | 6 +- include/exec/exec-all.h | 35 +++++++----- 4 files changed, 124 insertions(+), 76 deletions(-) (limited to 'accel/tcg/cpu-exec.c') diff --git a/accel/tcg/cpu-exec.c b/accel/tcg/cpu-exec.c index 45f6ebc65e..c482008bc7 100644 --- a/accel/tcg/cpu-exec.c +++ b/accel/tcg/cpu-exec.c @@ -352,28 +352,43 @@ void tb_set_jmp_target(TranslationBlock *tb, int n, uintptr_t addr) } } -/* Called with tb_lock held. */ static inline void tb_add_jump(TranslationBlock *tb, int n, TranslationBlock *tb_next) { + uintptr_t old; + assert(n < ARRAY_SIZE(tb->jmp_list_next)); - if (tb->jmp_list_next[n]) { - /* Another thread has already done this while we were - * outside of the lock; nothing to do in this case */ - return; + qemu_spin_lock(&tb_next->jmp_lock); + + /* make sure the destination TB is valid */ + if (tb_next->cflags & CF_INVALID) { + goto out_unlock_next; + } + /* Atomically claim the jump destination slot only if it was NULL */ + old = atomic_cmpxchg(&tb->jmp_dest[n], (uintptr_t)NULL, (uintptr_t)tb_next); + if (old) { + goto out_unlock_next; } + + /* patch the native jump address */ + tb_set_jmp_target(tb, n, (uintptr_t)tb_next->tc.ptr); + + /* add in TB jmp list */ + tb->jmp_list_next[n] = tb_next->jmp_list_head; + tb_next->jmp_list_head = (uintptr_t)tb | n; + + qemu_spin_unlock(&tb_next->jmp_lock); + qemu_log_mask_and_addr(CPU_LOG_EXEC, tb->pc, "Linking TBs %p [" TARGET_FMT_lx "] index %d -> %p [" TARGET_FMT_lx "]\n", tb->tc.ptr, tb->pc, n, tb_next->tc.ptr, tb_next->pc); + return; - /* patch the native jump address */ - tb_set_jmp_target(tb, n, (uintptr_t)tb_next->tc.ptr); - - /* add in TB jmp circular list */ - tb->jmp_list_next[n] = tb_next->jmp_list_first; - tb_next->jmp_list_first = (uintptr_t)tb | n; + out_unlock_next: + qemu_spin_unlock(&tb_next->jmp_lock); + return; } static inline TranslationBlock *tb_find(CPUState *cpu, @@ -416,9 +431,7 @@ static inline TranslationBlock *tb_find(CPUState *cpu, tb_lock(); acquired_tb_lock = true; } - if (!(tb->cflags & CF_INVALID)) { - tb_add_jump(last_tb, tb_exit, tb); - } + tb_add_jump(last_tb, tb_exit, tb); } if (acquired_tb_lock) { tb_unlock(); diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c index 3f977532bf..55c9e1b196 100644 --- a/accel/tcg/translate-all.c +++ b/accel/tcg/translate-all.c @@ -170,6 +170,9 @@ struct page_collection { #define PAGE_FOR_EACH_TB(pagedesc, tb, n) \ TB_FOR_EACH_TAGGED((pagedesc)->first_tb, tb, n, page_next) +#define TB_FOR_EACH_JMP(head_tb, tb, n) \ + TB_FOR_EACH_TAGGED((head_tb)->jmp_list_head, tb, n, jmp_list_next) + /* In system mode we want L1_MAP to be based on ram offsets, while in user mode we want it to be based on virtual addresses. */ #if !defined(CONFIG_USER_ONLY) @@ -389,7 +392,7 @@ static int cpu_restore_state_from_tb(CPUState *cpu, TranslationBlock *tb, return -1; found: - if (reset_icount && (tb->cflags & CF_USE_ICOUNT)) { + if (reset_icount && (tb_cflags(tb) & CF_USE_ICOUNT)) { assert(use_icount); /* Reset the cycle counter to the start of the block and shift if to the number of actually executed instructions */ @@ -432,7 +435,7 @@ bool cpu_restore_state(CPUState *cpu, uintptr_t host_pc, bool will_exit) tb = tcg_tb_lookup(host_pc); if (tb) { cpu_restore_state_from_tb(cpu, tb, host_pc, will_exit); - if (tb->cflags & CF_NOCACHE) { + if (tb_cflags(tb) & CF_NOCACHE) { /* one-shot translation, invalidate it immediately */ tb_phys_invalidate(tb, -1); tcg_tb_remove(tb); @@ -1360,34 +1363,53 @@ static inline void tb_page_remove(PageDesc *pd, TranslationBlock *tb) g_assert_not_reached(); } -/* remove the TB from a list of TBs jumping to the n-th jump target of the TB */ -static inline void tb_remove_from_jmp_list(TranslationBlock *tb, int n) +/* remove @orig from its @n_orig-th jump list */ +static inline void tb_remove_from_jmp_list(TranslationBlock *orig, int n_orig) { - TranslationBlock *tb1; - uintptr_t *ptb, ntb; - unsigned int n1; + uintptr_t ptr, ptr_locked; + TranslationBlock *dest; + TranslationBlock *tb; + uintptr_t *pprev; + int n; - ptb = &tb->jmp_list_next[n]; - if (*ptb) { - /* find tb(n) in circular list */ - for (;;) { - ntb = *ptb; - n1 = ntb & 3; - tb1 = (TranslationBlock *)(ntb & ~3); - if (n1 == n && tb1 == tb) { - break; - } - if (n1 == 2) { - ptb = &tb1->jmp_list_first; - } else { - ptb = &tb1->jmp_list_next[n1]; - } - } - /* now we can suppress tb(n) from the list */ - *ptb = tb->jmp_list_next[n]; + /* mark the LSB of jmp_dest[] so that no further jumps can be inserted */ + ptr = atomic_or_fetch(&orig->jmp_dest[n_orig], 1); + dest = (TranslationBlock *)(ptr & ~1); + if (dest == NULL) { + return; + } - tb->jmp_list_next[n] = (uintptr_t)NULL; + qemu_spin_lock(&dest->jmp_lock); + /* + * While acquiring the lock, the jump might have been removed if the + * destination TB was invalidated; check again. + */ + ptr_locked = atomic_read(&orig->jmp_dest[n_orig]); + if (ptr_locked != ptr) { + qemu_spin_unlock(&dest->jmp_lock); + /* + * The only possibility is that the jump was unlinked via + * tb_jump_unlink(dest). Seeing here another destination would be a bug, + * because we set the LSB above. + */ + g_assert(ptr_locked == 1 && dest->cflags & CF_INVALID); + return; } + /* + * We first acquired the lock, and since the destination pointer matches, + * we know for sure that @orig is in the jmp list. + */ + pprev = &dest->jmp_list_head; + TB_FOR_EACH_JMP(dest, tb, n) { + if (tb == orig && n == n_orig) { + *pprev = tb->jmp_list_next[n]; + /* no need to set orig->jmp_dest[n]; setting the LSB was enough */ + qemu_spin_unlock(&dest->jmp_lock); + return; + } + pprev = &tb->jmp_list_next[n]; + } + g_assert_not_reached(); } /* reset the jump entry 'n' of a TB so that it is not chained to @@ -1399,24 +1421,21 @@ static inline void tb_reset_jump(TranslationBlock *tb, int n) } /* remove any jumps to the TB */ -static inline void tb_jmp_unlink(TranslationBlock *tb) +static inline void tb_jmp_unlink(TranslationBlock *dest) { - TranslationBlock *tb1; - uintptr_t *ptb, ntb; - unsigned int n1; + TranslationBlock *tb; + int n; - ptb = &tb->jmp_list_first; - for (;;) { - ntb = *ptb; - n1 = ntb & 3; - tb1 = (TranslationBlock *)(ntb & ~3); - if (n1 == 2) { - break; - } - tb_reset_jump(tb1, n1); - *ptb = tb1->jmp_list_next[n1]; - tb1->jmp_list_next[n1] = (uintptr_t)NULL; + qemu_spin_lock(&dest->jmp_lock); + + TB_FOR_EACH_JMP(dest, tb, n) { + tb_reset_jump(tb, n); + atomic_and(&tb->jmp_dest[n], (uintptr_t)NULL | 1); + /* No need to clear the list entry; setting the dest ptr is enough */ } + dest->jmp_list_head = (uintptr_t)NULL; + + qemu_spin_unlock(&dest->jmp_lock); } /* If @rm_from_page_list is set, call with the TB's pages' locks held */ @@ -1429,11 +1448,14 @@ static void do_tb_phys_invalidate(TranslationBlock *tb, bool rm_from_page_list) assert_tb_locked(); + /* make sure no further incoming jumps will be chained to this TB */ + qemu_spin_lock(&tb->jmp_lock); atomic_set(&tb->cflags, tb->cflags | CF_INVALID); + qemu_spin_unlock(&tb->jmp_lock); /* remove the TB from the hash list */ phys_pc = tb->page_addr[0] + (tb->pc & ~TARGET_PAGE_MASK); - h = tb_hash_func(phys_pc, tb->pc, tb->flags, tb->cflags & CF_HASH_MASK, + h = tb_hash_func(phys_pc, tb->pc, tb->flags, tb_cflags(tb) & CF_HASH_MASK, tb->trace_vcpu_dstate); if (!qht_remove(&tb_ctx.htable, tb, h)) { return; @@ -1773,10 +1795,12 @@ TranslationBlock *tb_gen_code(CPUState *cpu, CODE_GEN_ALIGN)); /* init jump list */ - assert(((uintptr_t)tb & 3) == 0); - tb->jmp_list_first = (uintptr_t)tb | 2; + qemu_spin_init(&tb->jmp_lock); + tb->jmp_list_head = (uintptr_t)NULL; tb->jmp_list_next[0] = (uintptr_t)NULL; tb->jmp_list_next[1] = (uintptr_t)NULL; + tb->jmp_dest[0] = (uintptr_t)NULL; + tb->jmp_dest[1] = (uintptr_t)NULL; /* init original jump addresses wich has been set during tcg_gen_code() */ if (tb->jmp_reset_offset[0] != TB_JMP_RESET_OFFSET_INVALID) { @@ -1868,7 +1892,7 @@ tb_invalidate_phys_page_range__locked(struct page_collection *pages, } } if (current_tb == tb && - (current_tb->cflags & CF_COUNT_MASK) != 1) { + (tb_cflags(current_tb) & CF_COUNT_MASK) != 1) { /* If we are modifying the current TB, we must stop its execution. We could be more precise by checking that the modification is after the current PC, but it @@ -2067,7 +2091,7 @@ static bool tb_invalidate_phys_page(tb_page_addr_t addr, uintptr_t pc) PAGE_FOR_EACH_TB(p, tb, n) { #ifdef TARGET_HAS_PRECISE_SMC if (current_tb == tb && - (current_tb->cflags & CF_COUNT_MASK) != 1) { + (tb_cflags(current_tb) & CF_COUNT_MASK) != 1) { /* If we are modifying the current TB, we must stop its execution. We could be more precise by checking that the modification is after the current PC, but it @@ -2192,7 +2216,7 @@ void cpu_io_recompile(CPUState *cpu, uintptr_t retaddr) /* Generate a new TB executing the I/O insn. */ cpu->cflags_next_tb = curr_cflags() | CF_LAST_IO | n; - if (tb->cflags & CF_NOCACHE) { + if (tb_cflags(tb) & CF_NOCACHE) { if (tb->orig_tb) { /* Invalidate original TB if this TB was generated in * cpu_exec_nocache() */ diff --git a/docs/devel/multi-thread-tcg.txt b/docs/devel/multi-thread-tcg.txt index faf09c6069..df83445ccf 100644 --- a/docs/devel/multi-thread-tcg.txt +++ b/docs/devel/multi-thread-tcg.txt @@ -131,8 +131,10 @@ DESIGN REQUIREMENT: Safely handle invalidation of TBs The direct jump themselves are updated atomically by the TCG tb_set_jmp_target() code. Modification to the linked lists that allow -searching for linked pages are done under the protect of the -tb_lock(). +searching for linked pages are done under the protection of tb->jmp_lock, +where tb is the destination block of a jump. Each origin block keeps a +pointer to its destinations so that the appropriate lock can be acquired before +iterating over a jump list. The global page table is a lockless radix tree; cmpxchg is used to atomically insert new elements. diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h index 4f07a17052..3c2a0efb55 100644 --- a/include/exec/exec-all.h +++ b/include/exec/exec-all.h @@ -345,7 +345,7 @@ struct TranslationBlock { #define CF_LAST_IO 0x00008000 /* Last insn may be an IO access. */ #define CF_NOCACHE 0x00010000 /* To be freed after execution */ #define CF_USE_ICOUNT 0x00020000 -#define CF_INVALID 0x00040000 /* TB is stale. Setters need tb_lock */ +#define CF_INVALID 0x00040000 /* TB is stale. Set with @jmp_lock held */ #define CF_PARALLEL 0x00080000 /* Generate code for a parallel context */ /* cflags' mask for hashing/comparison */ #define CF_HASH_MASK \ @@ -364,6 +364,9 @@ struct TranslationBlock { uintptr_t page_next[2]; tb_page_addr_t page_addr[2]; + /* jmp_lock placed here to fill a 4-byte hole. Its documentation is below */ + QemuSpin jmp_lock; + /* The following data are used to directly call another TB from * the code of this one. This can be done either by emitting direct or * indirect native jump instructions. These jumps are reset so that the TB @@ -375,20 +378,26 @@ struct TranslationBlock { #define TB_JMP_RESET_OFFSET_INVALID 0xffff /* indicates no jump generated */ uintptr_t jmp_target_arg[2]; /* target address or offset */ - /* Each TB has an associated circular list of TBs jumping to this one. - * jmp_list_first points to the first TB jumping to this one. - * jmp_list_next is used to point to the next TB in a list. - * Since each TB can have two jumps, it can participate in two lists. - * jmp_list_first and jmp_list_next are 4-byte aligned pointers to a - * TranslationBlock structure, but the two least significant bits of - * them are used to encode which data field of the pointed TB should - * be used to traverse the list further from that TB: - * 0 => jmp_list_next[0], 1 => jmp_list_next[1], 2 => jmp_list_first. - * In other words, 0/1 tells which jump is used in the pointed TB, - * and 2 means that this is a pointer back to the target TB of this list. + /* + * Each TB has a NULL-terminated list (jmp_list_head) of incoming jumps. + * Each TB can have two outgoing jumps, and therefore can participate + * in two lists. The list entries are kept in jmp_list_next[2]. The least + * significant bit (LSB) of the pointers in these lists is used to encode + * which of the two list entries is to be used in the pointed TB. + * + * List traversals are protected by jmp_lock. The destination TB of each + * outgoing jump is kept in jmp_dest[] so that the appropriate jmp_lock + * can be acquired from any origin TB. + * + * jmp_dest[] are tagged pointers as well. The LSB is set when the TB is + * being invalidated, so that no further outgoing jumps from it can be set. + * + * jmp_lock also protects the CF_INVALID cflag; a jump must not be chained + * to a destination TB that has CF_INVALID set. */ + uintptr_t jmp_list_head; uintptr_t jmp_list_next[2]; - uintptr_t jmp_list_first; + uintptr_t jmp_dest[2]; }; extern bool parallel_cpus; -- cgit 1.4.1 From 0ac20318ce16f4de288969b2007ef5a654176058 Mon Sep 17 00:00:00 2001 From: "Emilio G. Cota" Date: Fri, 4 Aug 2017 23:46:31 -0400 Subject: tcg: remove tb_lock MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Use mmap_lock in user-mode to protect TCG state and the page descriptors. In !user-mode, each vCPU has its own TCG state, so no locks needed. Per-page locks are used to protect the page descriptors. Per-TB locks are used in both modes to protect TB jumps. Some notes: - tb_lock is removed from notdirty_mem_write by passing a locked page_collection to tb_invalidate_phys_page_fast. - tcg_tb_lookup/remove/insert/etc have their own internal lock(s), so there is no need to further serialize access to them. - do_tb_flush is run in a safe async context, meaning no other vCPU threads are running. Therefore acquiring mmap_lock there is just to please tools such as thread sanitizer. - Not visible in the diff, but tb_invalidate_phys_page already has an assert_memory_lock. - cpu_io_recompile is !user-only, so no mmap_lock there. - Added mmap_unlock()'s before all siglongjmp's that could be called in user-mode while mmap_lock is held. + Added an assert for !have_mmap_lock() after returning from the longjmp in cpu_exec, just like we do in cpu_exec_step_atomic. Performance numbers before/after: Host: AMD Opteron(tm) Processor 6376 ubuntu 17.04 ppc64 bootup+shutdown time 700 +-+--+----+------+------------+-----------+------------*--+-+ | + + + + + *B | | before ***B*** ** * | |tb lock removal ###D### *** | 600 +-+ *** +-+ | ** # | | *B* #D | | *** * ## | 500 +-+ *** ### +-+ | * *** ### | | *B* # ## | | ** * #D# | 400 +-+ ** ## +-+ | ** ### | | ** ## | | ** # ## | 300 +-+ * B* #D# +-+ | B *** ### | | * ** #### | | * *** ### | 200 +-+ B *B #D# +-+ | #B* * ## # | | #* ## | | + D##D# + + + + | 100 +-+--+----+------+------------+-----------+------------+--+-+ 1 8 16 Guest CPUs 48 64 png: https://imgur.com/HwmBHXe debian jessie aarch64 bootup+shutdown time 90 +-+--+-----+-----+------------+------------+------------+--+-+ | + + + + + + | | before ***B*** B | 80 +tb lock removal ###D### **D +-+ | **### | | **## | 70 +-+ ** # +-+ | ** ## | | ** # | 60 +-+ *B ## +-+ | ** ## | | *** #D | 50 +-+ *** ## +-+ | * ** ### | | **B* ### | 40 +-+ **** # ## +-+ | **** #D# | | ***B** ### | 30 +-+ B***B** #### +-+ | B * * # ### | | B ###D# | 20 +-+ D ##D## +-+ | D# | | + + + + + + | 10 +-+--+-----+-----+------------+------------+------------+--+-+ 1 8 16 Guest CPUs 48 64 png: https://imgur.com/iGpGFtv The gains are high for 4-8 CPUs. Beyond that point, however, unrelated lock contention significantly hurts scalability. Reviewed-by: Richard Henderson Reviewed-by: Alex Bennée Signed-off-by: Emilio G. Cota Signed-off-by: Richard Henderson --- accel/tcg/cpu-exec.c | 34 +++-------- accel/tcg/translate-all.c | 132 ++++++++++++---------------------------- accel/tcg/translate-all.h | 3 +- docs/devel/multi-thread-tcg.txt | 11 ++-- exec.c | 26 ++++---- include/exec/cpu-common.h | 2 +- include/exec/exec-all.h | 4 -- include/exec/memory-internal.h | 6 +- include/exec/tb-context.h | 2 - linux-user/main.c | 3 - tcg/tcg.h | 4 +- 11 files changed, 75 insertions(+), 152 deletions(-) (limited to 'accel/tcg/cpu-exec.c') diff --git a/accel/tcg/cpu-exec.c b/accel/tcg/cpu-exec.c index c482008bc7..c738b7f7d6 100644 --- a/accel/tcg/cpu-exec.c +++ b/accel/tcg/cpu-exec.c @@ -212,20 +212,20 @@ static void cpu_exec_nocache(CPUState *cpu, int max_cycles, We only end up here when an existing TB is too long. */ cflags |= MIN(max_cycles, CF_COUNT_MASK); - tb_lock(); + mmap_lock(); tb = tb_gen_code(cpu, orig_tb->pc, orig_tb->cs_base, orig_tb->flags, cflags); tb->orig_tb = orig_tb; - tb_unlock(); + mmap_unlock(); /* execute the generated code */ trace_exec_tb_nocache(tb, tb->pc); cpu_tb_exec(cpu, tb); - tb_lock(); + mmap_lock(); tb_phys_invalidate(tb, -1); + mmap_unlock(); tcg_tb_remove(tb); - tb_unlock(); } #endif @@ -244,9 +244,7 @@ void cpu_exec_step_atomic(CPUState *cpu) tb = tb_lookup__cpu_state(cpu, &pc, &cs_base, &flags, cf_mask); if (tb == NULL) { mmap_lock(); - tb_lock(); tb = tb_gen_code(cpu, pc, cs_base, flags, cflags); - tb_unlock(); mmap_unlock(); } @@ -261,15 +259,13 @@ void cpu_exec_step_atomic(CPUState *cpu) cpu_tb_exec(cpu, tb); cc->cpu_exec_exit(cpu); } else { - /* We may have exited due to another problem here, so we need - * to reset any tb_locks we may have taken but didn't release. + /* * The mmap_lock is dropped by tb_gen_code if it runs out of * memory. */ #ifndef CONFIG_SOFTMMU tcg_debug_assert(!have_mmap_lock()); #endif - tb_lock_reset(); assert_no_pages_locked(); } @@ -398,20 +394,11 @@ static inline TranslationBlock *tb_find(CPUState *cpu, TranslationBlock *tb; target_ulong cs_base, pc; uint32_t flags; - bool acquired_tb_lock = false; tb = tb_lookup__cpu_state(cpu, &pc, &cs_base, &flags, cf_mask); if (tb == NULL) { - /* mmap_lock is needed by tb_gen_code, and mmap_lock must be - * taken outside tb_lock. As system emulation is currently - * single threaded the locks are NOPs. - */ mmap_lock(); - tb_lock(); - acquired_tb_lock = true; - tb = tb_gen_code(cpu, pc, cs_base, flags, cf_mask); - mmap_unlock(); /* We add the TB in the virtual pc hash table for the fast lookup */ atomic_set(&cpu->tb_jmp_cache[tb_jmp_cache_hash_func(pc)], tb); @@ -427,15 +414,8 @@ static inline TranslationBlock *tb_find(CPUState *cpu, #endif /* See if we can patch the calling TB. */ if (last_tb && !qemu_loglevel_mask(CPU_LOG_TB_NOCHAIN)) { - if (!acquired_tb_lock) { - tb_lock(); - acquired_tb_lock = true; - } tb_add_jump(last_tb, tb_exit, tb); } - if (acquired_tb_lock) { - tb_unlock(); - } return tb; } @@ -710,7 +690,9 @@ int cpu_exec(CPUState *cpu) g_assert(cpu == current_cpu); g_assert(cc == CPU_GET_CLASS(cpu)); #endif /* buggy compiler */ - tb_lock_reset(); +#ifndef CONFIG_SOFTMMU + tcg_debug_assert(!have_mmap_lock()); +#endif if (qemu_mutex_iothread_locked()) { qemu_mutex_unlock_iothread(); } diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c index b33cd9bc98..f0c3fd4d03 100644 --- a/accel/tcg/translate-all.c +++ b/accel/tcg/translate-all.c @@ -88,13 +88,13 @@ #endif /* Access to the various translations structures need to be serialised via locks - * for consistency. This is automatic for SoftMMU based system - * emulation due to its single threaded nature. In user-mode emulation - * access to the memory related structures are protected with the - * mmap_lock. + * for consistency. + * In user-mode emulation access to the memory related structures are protected + * with mmap_lock. + * In !user-mode we use per-page locks. */ #ifdef CONFIG_SOFTMMU -#define assert_memory_lock() tcg_debug_assert(have_tb_lock) +#define assert_memory_lock() #else #define assert_memory_lock() tcg_debug_assert(have_mmap_lock()) #endif @@ -216,9 +216,6 @@ __thread TCGContext *tcg_ctx; TBContext tb_ctx; bool parallel_cpus; -/* translation block context */ -static __thread int have_tb_lock; - static void page_table_config_init(void) { uint32_t v_l1_bits; @@ -239,31 +236,6 @@ static void page_table_config_init(void) assert(v_l2_levels >= 0); } -#define assert_tb_locked() tcg_debug_assert(have_tb_lock) -#define assert_tb_unlocked() tcg_debug_assert(!have_tb_lock) - -void tb_lock(void) -{ - assert_tb_unlocked(); - qemu_mutex_lock(&tb_ctx.tb_lock); - have_tb_lock++; -} - -void tb_unlock(void) -{ - assert_tb_locked(); - have_tb_lock--; - qemu_mutex_unlock(&tb_ctx.tb_lock); -} - -void tb_lock_reset(void) -{ - if (have_tb_lock) { - qemu_mutex_unlock(&tb_ctx.tb_lock); - have_tb_lock = 0; - } -} - void cpu_gen_init(void) { tcg_context_init(&tcg_init_ctx); @@ -420,8 +392,7 @@ bool cpu_restore_state(CPUState *cpu, uintptr_t host_pc, bool will_exit) * - fault during translation (instruction fetch) * - fault from helper (not using GETPC() macro) * - * Either way we need return early to avoid blowing up on a - * recursive tb_lock() as we can't resolve it here. + * Either way we need return early as we can't resolve it here. * * We are using unsigned arithmetic so if host_pc < * tcg_init_ctx.code_gen_buffer check_offset will wrap to way @@ -430,7 +401,6 @@ bool cpu_restore_state(CPUState *cpu, uintptr_t host_pc, bool will_exit) check_offset = host_pc - (uintptr_t) tcg_init_ctx.code_gen_buffer; if (check_offset < tcg_init_ctx.code_gen_buffer_size) { - tb_lock(); tb = tcg_tb_lookup(host_pc); if (tb) { cpu_restore_state_from_tb(cpu, tb, host_pc, will_exit); @@ -441,7 +411,6 @@ bool cpu_restore_state(CPUState *cpu, uintptr_t host_pc, bool will_exit) } r = true; } - tb_unlock(); } return r; @@ -1130,7 +1099,6 @@ static inline void code_gen_alloc(size_t tb_size) fprintf(stderr, "Could not allocate dynamic translator buffer\n"); exit(1); } - qemu_mutex_init(&tb_ctx.tb_lock); } static bool tb_cmp(const void *ap, const void *bp) @@ -1174,14 +1142,12 @@ void tcg_exec_init(unsigned long tb_size) /* * Allocate a new translation block. Flush the translation buffer if * too many translation blocks or too much generated code. - * - * Called with tb_lock held. */ static TranslationBlock *tb_alloc(target_ulong pc) { TranslationBlock *tb; - assert_tb_locked(); + assert_memory_lock(); tb = tcg_tb_alloc(tcg_ctx); if (unlikely(tb == NULL)) { @@ -1248,8 +1214,7 @@ static gboolean tb_host_size_iter(gpointer key, gpointer value, gpointer data) /* flush all the translation blocks */ static void do_tb_flush(CPUState *cpu, run_on_cpu_data tb_flush_count) { - tb_lock(); - + mmap_lock(); /* If it is already been done on request of another CPU, * just retry. */ @@ -1279,7 +1244,7 @@ static void do_tb_flush(CPUState *cpu, run_on_cpu_data tb_flush_count) atomic_mb_set(&tb_ctx.tb_flush_count, tb_ctx.tb_flush_count + 1); done: - tb_unlock(); + mmap_unlock(); } void tb_flush(CPUState *cpu) @@ -1313,7 +1278,7 @@ do_tb_invalidate_check(struct qht *ht, void *p, uint32_t hash, void *userp) /* verify that all the pages have correct rights for code * - * Called with tb_lock held. + * Called with mmap_lock held. */ static void tb_invalidate_check(target_ulong address) { @@ -1343,7 +1308,10 @@ static void tb_page_check(void) #endif /* CONFIG_USER_ONLY */ -/* call with @pd->lock held */ +/* + * user-mode: call with mmap_lock held + * !user-mode: call with @pd->lock held + */ static inline void tb_page_remove(PageDesc *pd, TranslationBlock *tb) { TranslationBlock *tb1; @@ -1437,7 +1405,11 @@ static inline void tb_jmp_unlink(TranslationBlock *dest) qemu_spin_unlock(&dest->jmp_lock); } -/* If @rm_from_page_list is set, call with the TB's pages' locks held */ +/* + * In user-mode, call with mmap_lock held. + * In !user-mode, if @rm_from_page_list is set, call with the TB's pages' + * locks held. + */ static void do_tb_phys_invalidate(TranslationBlock *tb, bool rm_from_page_list) { CPUState *cpu; @@ -1445,7 +1417,7 @@ static void do_tb_phys_invalidate(TranslationBlock *tb, bool rm_from_page_list) uint32_t h; tb_page_addr_t phys_pc; - assert_tb_locked(); + assert_memory_lock(); /* make sure no further incoming jumps will be chained to this TB */ qemu_spin_lock(&tb->jmp_lock); @@ -1498,7 +1470,7 @@ static void tb_phys_invalidate__locked(TranslationBlock *tb) /* invalidate one TB * - * Called with tb_lock held. + * Called with mmap_lock held in user-mode. */ void tb_phys_invalidate(TranslationBlock *tb, tb_page_addr_t page_addr) { @@ -1543,7 +1515,7 @@ static void build_page_bitmap(PageDesc *p) /* add the tb in the target page and protect it if necessary * * Called with mmap_lock held for user-mode emulation. - * Called with @p->lock held. + * Called with @p->lock held in !user-mode. */ static inline void tb_page_add(PageDesc *p, TranslationBlock *tb, unsigned int n, tb_page_addr_t page_addr) @@ -1815,10 +1787,9 @@ TranslationBlock *tb_gen_code(CPUState *cpu, if ((pc & TARGET_PAGE_MASK) != virt_page2) { phys_page2 = get_page_addr_code(env, virt_page2); } - /* As long as consistency of the TB stuff is provided by tb_lock in user - * mode and is implicit in single-threaded softmmu emulation, no explicit - * memory barrier is required before tb_link_page() makes the TB visible - * through the physical hash table and physical page list. + /* + * No explicit memory barrier is required -- tb_link_page() makes the + * TB visible in a consistent state. */ existing_tb = tb_link_page(tb, phys_pc, phys_page2); /* if the TB already exists, discard what we just translated */ @@ -1834,8 +1805,9 @@ TranslationBlock *tb_gen_code(CPUState *cpu, } /* - * Call with all @pages locked. * @p must be non-NULL. + * user-mode: call with mmap_lock held. + * !user-mode: call with all @pages locked. */ static void tb_invalidate_phys_page_range__locked(struct page_collection *pages, @@ -1920,6 +1892,7 @@ tb_invalidate_phys_page_range__locked(struct page_collection *pages, page_collection_unlock(pages); /* Force execution of one insn next time. */ cpu->cflags_next_tb = 1 | curr_cflags(); + mmap_unlock(); cpu_loop_exit_noexc(cpu); } #endif @@ -1932,8 +1905,7 @@ tb_invalidate_phys_page_range__locked(struct page_collection *pages, * access: the virtual CPU will exit the current TB if code is modified inside * this TB. * - * Called with tb_lock/mmap_lock held for user-mode emulation - * Called with tb_lock held for system-mode emulation + * Called with mmap_lock held for user-mode emulation */ void tb_invalidate_phys_page_range(tb_page_addr_t start, tb_page_addr_t end, int is_cpu_write_access) @@ -1942,7 +1914,6 @@ void tb_invalidate_phys_page_range(tb_page_addr_t start, tb_page_addr_t end, PageDesc *p; assert_memory_lock(); - assert_tb_locked(); p = page_find(start >> TARGET_PAGE_BITS); if (p == NULL) { @@ -1961,14 +1932,15 @@ void tb_invalidate_phys_page_range(tb_page_addr_t start, tb_page_addr_t end, * access: the virtual CPU will exit the current TB if code is modified inside * this TB. * - * Called with mmap_lock held for user-mode emulation, grabs tb_lock - * Called with tb_lock held for system-mode emulation + * Called with mmap_lock held for user-mode emulation. */ -static void tb_invalidate_phys_range_1(tb_page_addr_t start, tb_page_addr_t end) +void tb_invalidate_phys_range(tb_page_addr_t start, tb_page_addr_t end) { struct page_collection *pages; tb_page_addr_t next; + assert_memory_lock(); + pages = page_collection_lock(start, end); for (next = (start & TARGET_PAGE_MASK) + TARGET_PAGE_SIZE; start < end; @@ -1984,30 +1956,16 @@ static void tb_invalidate_phys_range_1(tb_page_addr_t start, tb_page_addr_t end) page_collection_unlock(pages); } -#ifdef CONFIG_SOFTMMU -void tb_invalidate_phys_range(tb_page_addr_t start, tb_page_addr_t end) -{ - assert_tb_locked(); - tb_invalidate_phys_range_1(start, end); -} -#else -void tb_invalidate_phys_range(tb_page_addr_t start, tb_page_addr_t end) -{ - assert_memory_lock(); - tb_lock(); - tb_invalidate_phys_range_1(start, end); - tb_unlock(); -} -#endif - #ifdef CONFIG_SOFTMMU /* len must be <= 8 and start must be a multiple of len. * Called via softmmu_template.h when code areas are written to with * iothread mutex not held. + * + * Call with all @pages in the range [@start, @start + len[ locked. */ -void tb_invalidate_phys_page_fast(tb_page_addr_t start, int len) +void tb_invalidate_phys_page_fast(struct page_collection *pages, + tb_page_addr_t start, int len) { - struct page_collection *pages; PageDesc *p; #if 0 @@ -2026,7 +1984,6 @@ void tb_invalidate_phys_page_fast(tb_page_addr_t start, int len) return; } - pages = page_collection_lock(start, start + len); assert_page_locked(p); if (!p->code_bitmap && ++p->code_write_count >= SMC_BITMAP_USE_THRESHOLD) { @@ -2045,7 +2002,6 @@ void tb_invalidate_phys_page_fast(tb_page_addr_t start, int len) do_invalidate: tb_invalidate_phys_page_range__locked(pages, p, start, start + len, 1); } - page_collection_unlock(pages); } #else /* Called with mmap_lock held. If pc is not 0 then it indicates the @@ -2077,7 +2033,6 @@ static bool tb_invalidate_phys_page(tb_page_addr_t addr, uintptr_t pc) return false; } - tb_lock(); #ifdef TARGET_HAS_PRECISE_SMC if (p->first_tb && pc != 0) { current_tb = tcg_tb_lookup(pc); @@ -2110,12 +2065,9 @@ static bool tb_invalidate_phys_page(tb_page_addr_t addr, uintptr_t pc) if (current_tb_modified) { /* Force execution of one insn next time. */ cpu->cflags_next_tb = 1 | curr_cflags(); - /* tb_lock will be reset after cpu_loop_exit_noexc longjmps - * back into the cpu_exec loop. */ return true; } #endif - tb_unlock(); return false; } @@ -2136,18 +2088,18 @@ void tb_invalidate_phys_addr(AddressSpace *as, hwaddr addr, MemTxAttrs attrs) return; } ram_addr = memory_region_get_ram_addr(mr) + addr; - tb_lock(); tb_invalidate_phys_page_range(ram_addr, ram_addr + 1, 0); - tb_unlock(); rcu_read_unlock(); } #endif /* !defined(CONFIG_USER_ONLY) */ -/* Called with tb_lock held. */ +/* user-mode: call with mmap_lock held */ void tb_check_watchpoint(CPUState *cpu) { TranslationBlock *tb; + assert_memory_lock(); + tb = tcg_tb_lookup(cpu->mem_io_pc); if (tb) { /* We can use retranslation to find the PC. */ @@ -2181,7 +2133,6 @@ void cpu_io_recompile(CPUState *cpu, uintptr_t retaddr) TranslationBlock *tb; uint32_t n; - tb_lock(); tb = tcg_tb_lookup(retaddr); if (!tb) { cpu_abort(cpu, "cpu_io_recompile: could not find TB for pc=%p", @@ -2229,9 +2180,6 @@ void cpu_io_recompile(CPUState *cpu, uintptr_t retaddr) * repeating the fault, which is horribly inefficient. * Better would be to execute just this insn uncached, or generate a * second new TB. - * - * cpu_loop_exit_noexc will longjmp back to cpu_exec where the - * tb_lock gets reset. */ cpu_loop_exit_noexc(cpu); } diff --git a/accel/tcg/translate-all.h b/accel/tcg/translate-all.h index 6d1d2588b5..e6cb963d7e 100644 --- a/accel/tcg/translate-all.h +++ b/accel/tcg/translate-all.h @@ -26,7 +26,8 @@ struct page_collection *page_collection_lock(tb_page_addr_t start, tb_page_addr_t end); void page_collection_unlock(struct page_collection *set); -void tb_invalidate_phys_page_fast(tb_page_addr_t start, int len); +void tb_invalidate_phys_page_fast(struct page_collection *pages, + tb_page_addr_t start, int len); void tb_invalidate_phys_page_range(tb_page_addr_t start, tb_page_addr_t end, int is_cpu_write_access); void tb_invalidate_phys_range(tb_page_addr_t start, tb_page_addr_t end); diff --git a/docs/devel/multi-thread-tcg.txt b/docs/devel/multi-thread-tcg.txt index df83445ccf..06530be1e9 100644 --- a/docs/devel/multi-thread-tcg.txt +++ b/docs/devel/multi-thread-tcg.txt @@ -61,6 +61,7 @@ have their block-to-block jumps patched. Global TCG State ---------------- +### User-mode emulation We need to protect the entire code generation cycle including any post generation patching of the translated code. This also implies a shared translation buffer which contains code running on all cores. Any @@ -75,9 +76,11 @@ patching. (Current solution) -Mainly as part of the linux-user work all code generation is -serialised with a tb_lock(). For the SoftMMU tb_lock() also takes the -place of mmap_lock() in linux-user. +Code generation is serialised with mmap_lock(). + +### !User-mode emulation +Each vCPU has its own TCG context and associated TCG region, thereby +requiring no locking. Translation Blocks ------------------ @@ -195,7 +198,7 @@ work as "safe work" and exiting the cpu run loop. This ensure by the time execution restarts all flush operations have completed. TLB flag updates are all done atomically and are also protected by the -tb_lock() which is used by the functions that update the TLB in bulk. +corresponding page lock. (Known limitation) diff --git a/exec.c b/exec.c index ebadc0e302..28f9bdcbf9 100644 --- a/exec.c +++ b/exec.c @@ -1031,9 +1031,7 @@ const char *parse_cpu_model(const char *cpu_model) static void breakpoint_invalidate(CPUState *cpu, target_ulong pc) { mmap_lock(); - tb_lock(); tb_invalidate_phys_page_range(pc, pc + 1, 0); - tb_unlock(); mmap_unlock(); } #else @@ -2644,21 +2642,21 @@ void memory_notdirty_write_prepare(NotDirtyInfo *ndi, ndi->ram_addr = ram_addr; ndi->mem_vaddr = mem_vaddr; ndi->size = size; - ndi->locked = false; + ndi->pages = NULL; assert(tcg_enabled()); if (!cpu_physical_memory_get_dirty_flag(ram_addr, DIRTY_MEMORY_CODE)) { - ndi->locked = true; - tb_lock(); - tb_invalidate_phys_page_fast(ram_addr, size); + ndi->pages = page_collection_lock(ram_addr, ram_addr + size); + tb_invalidate_phys_page_fast(ndi->pages, ram_addr, size); } } /* Called within RCU critical section. */ void memory_notdirty_write_complete(NotDirtyInfo *ndi) { - if (ndi->locked) { - tb_unlock(); + if (ndi->pages) { + page_collection_unlock(ndi->pages); + ndi->pages = NULL; } /* Set both VGA and migration bits for simplicity and to remove @@ -2745,18 +2743,16 @@ static void check_watchpoint(int offset, int len, MemTxAttrs attrs, int flags) } cpu->watchpoint_hit = wp; - /* Both tb_lock and iothread_mutex will be reset when - * cpu_loop_exit or cpu_loop_exit_noexc longjmp - * back into the cpu_exec main loop. - */ - tb_lock(); + mmap_lock(); tb_check_watchpoint(cpu); if (wp->flags & BP_STOP_BEFORE_ACCESS) { cpu->exception_index = EXCP_DEBUG; + mmap_unlock(); cpu_loop_exit(cpu); } else { /* Force execution of one insn next time. */ cpu->cflags_next_tb = 1 | curr_cflags(); + mmap_unlock(); cpu_loop_exit_noexc(cpu); } } @@ -3147,9 +3143,9 @@ static void invalidate_and_set_dirty(MemoryRegion *mr, hwaddr addr, } if (dirty_log_mask & (1 << DIRTY_MEMORY_CODE)) { assert(tcg_enabled()); - tb_lock(); + mmap_lock(); tb_invalidate_phys_range(addr, addr + length); - tb_unlock(); + mmap_unlock(); dirty_log_mask &= ~(1 << DIRTY_MEMORY_CODE); } cpu_physical_memory_set_dirty_range(addr, length, dirty_log_mask); diff --git a/include/exec/cpu-common.h b/include/exec/cpu-common.h index 0b58e262f3..18b40d6145 100644 --- a/include/exec/cpu-common.h +++ b/include/exec/cpu-common.h @@ -23,7 +23,7 @@ typedef struct CPUListState { FILE *file; } CPUListState; -/* The CPU list lock nests outside tb_lock/tb_unlock. */ +/* The CPU list lock nests outside page_(un)lock or mmap_(un)lock */ void qemu_init_cpu_list(void); void cpu_list_lock(void); void cpu_list_unlock(void); diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h index 3c2a0efb55..25a6f28ab8 100644 --- a/include/exec/exec-all.h +++ b/include/exec/exec-all.h @@ -440,10 +440,6 @@ extern uintptr_t tci_tb_ptr; smaller than 4 bytes, so we don't worry about special-casing this. */ #define GETPC_ADJ 2 -void tb_lock(void); -void tb_unlock(void); -void tb_lock_reset(void); - #if !defined(CONFIG_USER_ONLY) && defined(CONFIG_DEBUG_TCG) void assert_no_pages_locked(void); #else diff --git a/include/exec/memory-internal.h b/include/exec/memory-internal.h index 56c25c0ef7..bb08fa4d2f 100644 --- a/include/exec/memory-internal.h +++ b/include/exec/memory-internal.h @@ -49,6 +49,8 @@ void mtree_print_dispatch(fprintf_function mon, void *f, struct AddressSpaceDispatch *d, MemoryRegion *root); +struct page_collection; + /* Opaque struct for passing info from memory_notdirty_write_prepare() * to memory_notdirty_write_complete(). Callers should treat all fields * as private, with the exception of @active. @@ -60,10 +62,10 @@ void mtree_print_dispatch(fprintf_function mon, void *f, */ typedef struct { CPUState *cpu; + struct page_collection *pages; ram_addr_t ram_addr; vaddr mem_vaddr; unsigned size; - bool locked; bool active; } NotDirtyInfo; @@ -91,7 +93,7 @@ typedef struct { * * This must only be called if we are using TCG; it will assert otherwise. * - * We may take a lock in the prepare call, so callers must ensure that + * We may take locks in the prepare call, so callers must ensure that * they don't exit (via longjump or otherwise) without calling complete. * * This call must only be made inside an RCU critical section. diff --git a/include/exec/tb-context.h b/include/exec/tb-context.h index 8c9b49c98e..feb585e0a7 100644 --- a/include/exec/tb-context.h +++ b/include/exec/tb-context.h @@ -32,8 +32,6 @@ typedef struct TBContext TBContext; struct TBContext { struct qht htable; - /* any access to the tbs or the page table must use this lock */ - QemuMutex tb_lock; /* statistics */ unsigned tb_flush_count; diff --git a/linux-user/main.c b/linux-user/main.c index 78d6d3e7eb..84e9ec9335 100644 --- a/linux-user/main.c +++ b/linux-user/main.c @@ -120,7 +120,6 @@ void fork_start(void) { start_exclusive(); mmap_fork_start(); - qemu_mutex_lock(&tb_ctx.tb_lock); cpu_list_lock(); } @@ -136,14 +135,12 @@ void fork_end(int child) QTAILQ_REMOVE(&cpus, cpu, node); } } - qemu_mutex_init(&tb_ctx.tb_lock); qemu_init_cpu_list(); gdbserver_fork(thread_cpu); /* qemu_init_cpu_list() takes care of reinitializing the * exclusive state, so we don't need to end_exclusive() here. */ } else { - qemu_mutex_unlock(&tb_ctx.tb_lock); cpu_list_unlock(); end_exclusive(); } diff --git a/tcg/tcg.h b/tcg/tcg.h index e49b289ba1..532d2a0710 100644 --- a/tcg/tcg.h +++ b/tcg/tcg.h @@ -857,7 +857,7 @@ static inline bool tcg_op_buf_full(void) /* pool based memory allocation */ -/* user-mode: tb_lock must be held for tcg_malloc_internal. */ +/* user-mode: mmap_lock must be held for tcg_malloc_internal. */ void *tcg_malloc_internal(TCGContext *s, int size); void tcg_pool_reset(TCGContext *s); TranslationBlock *tcg_tb_alloc(TCGContext *s); @@ -875,7 +875,7 @@ TranslationBlock *tcg_tb_lookup(uintptr_t tc_ptr); void tcg_tb_foreach(GTraverseFunc func, gpointer user_data); size_t tcg_nb_tbs(void); -/* user-mode: Called with tb_lock held. */ +/* user-mode: Called with mmap_lock held. */ static inline void *tcg_malloc(int size) { TCGContext *s = tcg_ctx; -- cgit 1.4.1