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system/cpus: rename qemu_mutex_lock_iothread() to bql_lock()

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The Big QEMU Lock (BQL) has many names and they are confusing. The
actual QemuMutex variable is called qemu_global_mutex but it's commonly
referred to as the BQL in discussions and some code comments. The
locking APIs, however, are called qemu_mutex_lock_iothread() and
qemu_mutex_unlock_iothread().

The "iothread" name is historic and comes from when the main thread was
split into into KVM vcpu threads and the "iothread" (now called the main
loop thread). I have contributed to the confusion myself by introducing
a separate --object iothread, a separate concept unrelated to the BQL.

The "iothread" name is no longer appropriate for the BQL. Rename the
locking APIs to:
- void bql_lock(void)
- void bql_unlock(void)
- bool bql_locked(void)

There are more APIs with "iothread" in their names. Subsequent patches
will rename them. There are also comments and documentation that will be
updated in later patches.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Paul Durrant <paul@xen.org>
Acked-by: Fabiano Rosas <farosas@suse.de>
Acked-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Acked-by: Peter Xu <peterx@redhat.com>
Acked-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
Acked-by: Hyman Huang <yong.huang@smartx.com>
Reviewed-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Message-id: 20240102153529.486531-2-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2024-01-02 10:35:25 -05:00
parent 897a06c6d7
commit 195801d700
95 changed files with 529 additions and 529 deletions
Download patch file Download diff file Expand all files Collapse all files

4
target/i386/nvmm/nvmm-accel-ops.c
View file

@ -25,7 +25,7 @@ static void *qemu_nvmm_cpu_thread_fn(void *arg)
rcu_register_thread();
qemu_mutex_lock_iothread();
bql_lock();
qemu_thread_get_self(cpu->thread);
cpu->thread_id = qemu_get_thread_id();
current_cpu = cpu;
@ -55,7 +55,7 @@ static void *qemu_nvmm_cpu_thread_fn(void *arg)
nvmm_destroy_vcpu(cpu);
cpu_thread_signal_destroyed(cpu);
qemu_mutex_unlock_iothread();
bql_unlock();
rcu_unregister_thread();
return NULL;
}

20
target/i386/nvmm/nvmm-all.c
View file

@ -399,7 +399,7 @@ nvmm_vcpu_pre_run(CPUState *cpu)
uint8_t tpr;
int ret;
qemu_mutex_lock_iothread();
bql_lock();
tpr = cpu_get_apic_tpr(x86_cpu->apic_state);
if (tpr != qcpu->tpr) {
@ -462,7 +462,7 @@ nvmm_vcpu_pre_run(CPUState *cpu)
}
}
qemu_mutex_unlock_iothread();
bql_unlock();
}
/*
@ -485,9 +485,9 @@ nvmm_vcpu_post_run(CPUState *cpu, struct nvmm_vcpu_exit *exit)
tpr = exit->exitstate.cr8;
if (qcpu->tpr != tpr) {
qcpu->tpr = tpr;
qemu_mutex_lock_iothread();
bql_lock();
cpu_set_apic_tpr(x86_cpu->apic_state, qcpu->tpr);
qemu_mutex_unlock_iothread();
bql_unlock();
}
}
@ -648,7 +648,7 @@ nvmm_handle_halted(struct nvmm_machine *mach, CPUState *cpu,
CPUX86State *env = cpu_env(cpu);
int ret = 0;
qemu_mutex_lock_iothread();
bql_lock();
if (!((cpu->interrupt_request & CPU_INTERRUPT_HARD) &&
(env->eflags & IF_MASK)) &&
@ -658,7 +658,7 @@ nvmm_handle_halted(struct nvmm_machine *mach, CPUState *cpu,
ret = 1;
}
qemu_mutex_unlock_iothread();
bql_unlock();
return ret;
}
@ -721,7 +721,7 @@ nvmm_vcpu_loop(CPUState *cpu)
return 0;
}
qemu_mutex_unlock_iothread();
bql_unlock();
cpu_exec_start(cpu);
/*
@ -806,16 +806,16 @@ nvmm_vcpu_loop(CPUState *cpu)
error_report("NVMM: Unexpected VM exit code 0x%lx [hw=0x%lx]",
exit->reason, exit->u.inv.hwcode);
nvmm_get_registers(cpu);
qemu_mutex_lock_iothread();
bql_lock();
qemu_system_guest_panicked(cpu_get_crash_info(cpu));
qemu_mutex_unlock_iothread();
bql_unlock();
ret = -1;
break;
}
} while (ret == 0);
cpu_exec_end(cpu);
qemu_mutex_lock_iothread();
bql_lock();
qatomic_set(&cpu->exit_request, false);