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Re: [Qemu-devel] [PATCH 1/2] CPUArchState: introduce per-cpu lock
From: |
Andreas Färber |
Subject: |
Re: [Qemu-devel] [PATCH 1/2] CPUArchState: introduce per-cpu lock |
Date: |
Fri, 22 Jun 2012 14:55:27 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:12.0) Gecko/20120421 Thunderbird/12.0 |
Am 21.06.2012 17:06, schrieb Liu Ping Fan:
> introduce a lock for per-cpu to protect agaist accesing from
> other vcpu thread.
>
> Signed-off-by: Liu Ping Fan <address@hidden>
> ---
> cpu-defs.h | 2 ++
> cpus.c | 17 +++++++++++++++++
> main-loop.h | 3 +++
> 3 files changed, 22 insertions(+), 0 deletions(-)
>
> diff --git a/cpu-defs.h b/cpu-defs.h
> index f49e950..7305822 100644
> --- a/cpu-defs.h
> +++ b/cpu-defs.h
> @@ -30,6 +30,7 @@
> #include "osdep.h"
> #include "qemu-queue.h"
> #include "targphys.h"
> +#include "qemu-thread-posix.h"
>
> #ifndef TARGET_LONG_BITS
> #error TARGET_LONG_BITS must be defined before including this header
> @@ -220,6 +221,7 @@ typedef struct CPUWatchpoint {
> CPU_COMMON_THREAD \
> struct QemuCond *halt_cond; \
> int thread_kicked; \
> + struct QemuMutex *cpu_lock; \
> struct qemu_work_item *queued_work_first, *queued_work_last; \
> const char *cpu_model_str; \
> struct KVMState *kvm_state; \
Please don't add stuff to CPU_COMMON. Instead add to CPUState in
qom/cpu.c. The QOM CPUState part 4 series moves many of those fields there.
> diff --git a/cpus.c b/cpus.c
> index b182b3d..554f7bc 100644
> --- a/cpus.c
> +++ b/cpus.c
> @@ -735,6 +735,7 @@ static void *qemu_kvm_cpu_thread_fn(void *arg)
> env->thread_id = qemu_get_thread_id();
> cpu_single_env = env;
>
> +
Stray whitespace addition.
> r = kvm_init_vcpu(env);
> if (r < 0) {
> fprintf(stderr, "kvm_init_vcpu failed: %s\n", strerror(-r));
> @@ -891,6 +892,20 @@ int qemu_cpu_is_self(void *_env)
> return qemu_thread_is_self(env->thread);
> }
>
> +void qemu_mutex_lock_cpu(void *_env)
> +{
> + CPUArchState *env = _env;
> +
> + qemu_mutex_lock(env->cpu_lock);
> +}
> +
> +void qemu_mutex_unlock_cpu(void *_env)
> +{
> + CPUArchState *env = _env;
> +
> + qemu_mutex_unlock(env->cpu_lock);
> +}
> +
I don't like these helpers. For one, you are using void * arguments and
casting them, for another you are using CPUArchState at all. With my
suggestion above these can be CPUState *cpu.
> void qemu_mutex_lock_iothread(void)
> {
> if (!tcg_enabled()) {
> @@ -1027,6 +1042,8 @@ void qemu_init_vcpu(void *_env)
> env->nr_cores = smp_cores;
> env->nr_threads = smp_threads;
> env->stopped = 1;
> + env->cpu_lock = g_malloc0(sizeof(QemuMutex));
> + qemu_mutex_init(env->cpu_lock);
Are you sure this is not needed for linux-user/bsd-user? If not needed,
then the field should be #ifdef'ed in the struct to assure that.
Otherwise this function is never called and you need to move the
initialization to the initfn in qom/cpu.c and then should also clean it
up in a finalizer.
Andreas
> if (kvm_enabled()) {
> qemu_kvm_start_vcpu(env);
> } else if (tcg_enabled()) {
> diff --git a/main-loop.h b/main-loop.h
> index dce1cd9..d8d44a4 100644
> --- a/main-loop.h
> +++ b/main-loop.h
> @@ -323,6 +323,9 @@ void qemu_bh_delete(QEMUBH *bh);
> int qemu_add_child_watch(pid_t pid);
> #endif
>
> +void qemu_mutex_lock_cpu(void *_env);
> +void qemu_mutex_unlock_cpu(void *_env);
> +
> /**
> * qemu_mutex_lock_iothread: Lock the main loop mutex.
> *
--
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[Qemu-devel] [PATCH 2/2] kvm: use per-cpu lock to free vcpu thread out of the big lock, Liu Ping Fan, 2012/06/21