[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Qemu-devel] [PATCH 3/9] tcg: introduce tcg_current_cpu
From: |
Paolo Bonzini |
Subject: |
[Qemu-devel] [PATCH 3/9] tcg: introduce tcg_current_cpu |
Date: |
Wed, 26 Aug 2015 02:17:39 +0200 |
This is already useful on Windows in order to remove tls.h, because
accesses to current_cpu are done from a different thread on that
platform. It will be used on POSIX platforms as soon TCG stops using
signals to interrupt the execution of translated code.
Signed-off-by: Paolo Bonzini <address@hidden>
---
cpu-exec.c | 14 +++++---------
cpus.c | 5 +++--
include/exec/exec-all.h | 1 +
3 files changed, 9 insertions(+), 11 deletions(-)
diff --git a/cpu-exec.c b/cpu-exec.c
index 58144b4..2c3cb7d 100644
--- a/cpu-exec.c
+++ b/cpu-exec.c
@@ -382,6 +382,7 @@ static void cpu_handle_debug_exception(CPUState *cpu)
/* main execution loop */
volatile sig_atomic_t exit_request;
+CPUState *tcg_current_cpu;
int cpu_exec(CPUState *cpu)
{
@@ -405,15 +406,7 @@ int cpu_exec(CPUState *cpu)
}
current_cpu = cpu;
-
- /* As long as current_cpu is null, up to the assignment just above,
- * requests by other threads to exit the execution loop are expected to
- * be issued using the exit_request global. We must make sure that our
- * evaluation of the global value is performed past the current_cpu
- * value transition point, which requires a memory barrier as well as
- * an instruction scheduling constraint on modern architectures. */
- smp_mb();
-
+ atomic_mb_set(&tcg_current_cpu, cpu);
rcu_read_lock();
if (unlikely(exit_request)) {
@@ -614,5 +607,8 @@ int cpu_exec(CPUState *cpu)
/* fail safe : never use current_cpu outside cpu_exec() */
current_cpu = NULL;
+
+ /* Does not need atomic_mb_set because a spurious wakeup is okay. */
+ atomic_set(&tcg_current_cpu, NULL);
return ret;
}
diff --git a/cpus.c b/cpus.c
index 8884278..ec8168c 100644
--- a/cpus.c
+++ b/cpus.c
@@ -663,8 +663,9 @@ static void cpu_handle_guest_debug(CPUState *cpu)
static void cpu_signal(int sig)
{
- if (current_cpu) {
- cpu_exit(current_cpu);
+ CPUState *cpu = atomic_mb_read(&tcg_current_cpu);
+ if (cpu) {
+ cpu_exit(cpu);
}
exit_request = 1;
}
diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h
index b3f900a..c92d434 100644
--- a/include/exec/exec-all.h
+++ b/include/exec/exec-all.h
@@ -346,6 +346,7 @@ tb_page_addr_t get_page_addr_code(CPUArchState *env1,
target_ulong addr);
extern int singlestep;
/* cpu-exec.c */
+extern CPUState *tcg_current_cpu;
extern volatile sig_atomic_t exit_request;
#endif
--
2.4.3
- [Qemu-devel] [PATCH v2 0/9] tcg: signal-free qemu_cpu_kick, Paolo Bonzini, 2015/08/25
- [Qemu-devel] [PATCH 3/9] tcg: introduce tcg_current_cpu,
Paolo Bonzini <=
- [Qemu-devel] [PATCH 1/9] i8257: rewrite DMA_schedule to avoid hooking into the CPU loop, Paolo Bonzini, 2015/08/25
- [Qemu-devel] [PATCH 5/9] tcg: assign cpu->current_tb in a simpler place, Paolo Bonzini, 2015/08/25
- [Qemu-devel] [PATCH 2/9] i8257: remove cpu_request_exit irq, Paolo Bonzini, 2015/08/25
- [Qemu-devel] [PATCH 6/9] tcg: synchronize cpu->exit_request and cpu->tcg_exit_req accesses, Paolo Bonzini, 2015/08/25
- [Qemu-devel] [PATCH 4/9] remove qemu/tls.h, Paolo Bonzini, 2015/08/25
- [Qemu-devel] [PATCH 7/9] tcg: synchronize exit_request and tcg_current_cpu accesses, Paolo Bonzini, 2015/08/25
- [Qemu-devel] [PATCH 8/9] use qemu_cpu_kick instead of cpu_exit or qemu_cpu_kick_thread, Paolo Bonzini, 2015/08/25
- [Qemu-devel] [PATCH 9/9] tcg: signal-free qemu_cpu_kick, Paolo Bonzini, 2015/08/25