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Groups > linux.kernel > #1336690
| From | Radim Krčmář <rkrcmar@redhat.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH v2 07/14] KVM: x86: remove unnecessary uses of PIT state lock |
| Date | 2016-02-17 20:20 +0100 |
| Message-ID | <r3fNN-2nq-53@gated-at.bofh.it> (permalink) |
| References | <r3fNM-2nq-7@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
- kvm_create_pit had to lock only because it exposed kvm->arch.vpit very
early, but initialization doesn't use kvm->arch.vpit since the last
patch, so we can drop locking.
- kvm_free_pit is only run after there are no users of KVM and therefore
is the sole actor.
- Locking in kvm_vm_ioctl_reinject doesn't do anything, because reinject
is only protected at that place.
- kvm_pit_reset isn't used anywhere and its locking can be dropped if we
hide it.
Removing useless locking allows to see what actually is being protected
by PIT state lock (values accessible from the guest).
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
---
v2: new
arch/x86/kvm/i8254.c | 7 -------
arch/x86/kvm/i8254.h | 7 ++++---
arch/x86/kvm/x86.c | 4 ++--
3 files changed, 6 insertions(+), 12 deletions(-)
diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c
index c11734dd5092..01f9c70ebc21 100644
--- a/arch/x86/kvm/i8254.c
+++ b/arch/x86/kvm/i8254.c
@@ -612,7 +612,6 @@ void kvm_pit_reset(struct kvm_pit *pit)
int i;
struct kvm_kpit_channel_state *c;
- mutex_lock(&pit->pit_state.lock);
pit->pit_state.flags = 0;
for (i = 0; i < 3; i++) {
c = &pit->pit_state.channels[i];
@@ -620,7 +619,6 @@ void kvm_pit_reset(struct kvm_pit *pit)
c->gate = (i != 2);
pit_load_count(pit, i, 0);
}
- mutex_unlock(&pit->pit_state.lock);
kvm_pit_reset_reinject(pit);
}
@@ -663,7 +661,6 @@ struct kvm_pit *kvm_create_pit(struct kvm *kvm, u32 flags)
}
mutex_init(&pit->pit_state.lock);
- mutex_lock(&pit->pit_state.lock);
pid = get_pid(task_tgid(current));
pid_nr = pid_vnr(pid);
@@ -673,7 +670,6 @@ struct kvm_pit *kvm_create_pit(struct kvm *kvm, u32 flags)
pit->worker_task = kthread_run(kthread_worker_fn, &pit->worker,
"kvm-pit/%d", pid_nr);
if (IS_ERR(pit->worker_task)) {
- mutex_unlock(&pit->pit_state.lock);
kvm_free_irq_source_id(kvm, pit->irq_source_id);
kfree(pit);
return NULL;
@@ -689,7 +685,6 @@ struct kvm_pit *kvm_create_pit(struct kvm *kvm, u32 flags)
pit_state->irq_ack_notifier.irq_acked = kvm_pit_ack_irq;
kvm_register_irq_ack_notifier(kvm, &pit_state->irq_ack_notifier);
pit_state->reinject = true;
- mutex_unlock(&pit->pit_state.lock);
kvm_pit_reset(pit);
@@ -737,13 +732,11 @@ void kvm_free_pit(struct kvm *kvm)
&kvm->arch.vpit->mask_notifier);
kvm_unregister_irq_ack_notifier(kvm,
&kvm->arch.vpit->pit_state.irq_ack_notifier);
- mutex_lock(&kvm->arch.vpit->pit_state.lock);
timer = &kvm->arch.vpit->pit_state.timer;
hrtimer_cancel(timer);
flush_kthread_work(&kvm->arch.vpit->expired);
kthread_stop(kvm->arch.vpit->worker_task);
kvm_free_irq_source_id(kvm, kvm->arch.vpit->irq_source_id);
- mutex_unlock(&kvm->arch.vpit->pit_state.lock);
kfree(kvm->arch.vpit);
}
}
diff --git a/arch/x86/kvm/i8254.h b/arch/x86/kvm/i8254.h
index a6aceaf08df5..568d87ec3698 100644
--- a/arch/x86/kvm/i8254.h
+++ b/arch/x86/kvm/i8254.h
@@ -22,17 +22,19 @@ struct kvm_kpit_channel_state {
};
struct kvm_kpit_state {
+ /* All members before "struct mutex lock" are protected by the lock. */
struct kvm_kpit_channel_state channels[3];
u32 flags;
bool is_periodic;
s64 period; /* unit: ns */
struct hrtimer timer;
- atomic_t pending; /* accumulated triggered timers */
bool reinject;
- struct kvm *kvm;
u32 speaker_data_on;
+
struct mutex lock;
+ struct kvm *kvm;
struct kvm_pit *pit;
+ atomic_t pending; /* accumulated triggered timers */
atomic_t irq_ack;
struct kvm_irq_ack_notifier irq_ack_notifier;
};
@@ -59,7 +61,6 @@ struct kvm_pit {
struct kvm_pit *kvm_create_pit(struct kvm *kvm, u32 flags);
void kvm_free_pit(struct kvm *kvm);
-void kvm_pit_reset(struct kvm_pit *pit);
void kvm_pit_load_count(struct kvm_pit *pit, int channel, u32 val,
int hpet_legacy_start);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 57b296466bf0..f2f7ba74da6b 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3685,9 +3685,9 @@ static int kvm_vm_ioctl_reinject(struct kvm *kvm,
{
if (!kvm->arch.vpit)
return -ENXIO;
- mutex_lock(&kvm->arch.vpit->pit_state.lock);
+
kvm->arch.vpit->pit_state.reinject = control->pit_reinject;
- mutex_unlock(&kvm->arch.vpit->pit_state.lock);
+
return 0;
}
--
2.7.1
Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
[PATCH v2 00/14] KVM: x86: change PIT discard policy and untangle related code Radim Krčmář <rkrcmar@redhat.com> - 2016-02-17 20:20 +0100
[PATCH v2 02/14] KVM: x86: simplify atomics in kvm_pit_ack_irq Radim Krčmář <rkrcmar@redhat.com> - 2016-02-17 20:20 +0100
Re: [PATCH v2 02/14] KVM: x86: simplify atomics in kvm_pit_ack_irq Paolo Bonzini <pbonzini@redhat.com> - 2016-02-18 19:10 +0100
Re: [PATCH v2 02/14] KVM: x86: simplify atomics in kvm_pit_ack_irq Paolo Bonzini <pbonzini@redhat.com> - 2016-02-19 17:00 +0100
Re: [PATCH v2 02/14] KVM: x86: simplify atomics in kvm_pit_ack_irq Radim Krčmář <rkrcmar@redhat.com> - 2016-02-19 17:00 +0100
[PATCH v2 14/14] KVM: x86: move PIT timer function initialization Radim Krčmář <rkrcmar@redhat.com> - 2016-02-17 20:20 +0100
[PATCH v2 05/14] KVM: x86: tone down WARN_ON pit.state_lock Radim Krčmář <rkrcmar@redhat.com> - 2016-02-17 20:20 +0100
[PATCH v2 06/14] KVM: x86: pass struct kvm_pit instead of kvm in PIT Radim Krčmář <rkrcmar@redhat.com> - 2016-02-17 20:20 +0100
[PATCH v2 09/14] KVM: x86: refactor kvm_create_pit Radim Krčmář <rkrcmar@redhat.com> - 2016-02-17 20:20 +0100
[PATCH v2 04/14] KVM: x86: use atomic_t instead of pit.inject_lock Radim Krčmář <rkrcmar@redhat.com> - 2016-02-17 20:20 +0100
[PATCH v2 13/14] KVM: x86: don't assume layout of kvm_kpit_state Radim Krčmář <rkrcmar@redhat.com> - 2016-02-17 20:20 +0100
[PATCH v2 01/14] KVM: x86: change PIT discard tick policy Radim Krčmář <rkrcmar@redhat.com> - 2016-02-17 20:20 +0100
Re: [PATCH v2 01/14] KVM: x86: change PIT discard tick policy Paolo Bonzini <pbonzini@redhat.com> - 2016-02-18 17:20 +0100
Re: [PATCH v2 01/14] KVM: x86: change PIT discard tick policy Radim Krčmář <rkrcmar@redhat.com> - 2016-02-18 18:00 +0100
Re: [PATCH v2 01/14] KVM: x86: change PIT discard tick policy Paolo Bonzini <pbonzini@redhat.com> - 2016-02-18 18:40 +0100
Re: [PATCH v2 01/14] KVM: x86: change PIT discard tick policy Paolo Bonzini <pbonzini@redhat.com> - 2016-02-18 19:00 +0100
Re: [PATCH v2 01/14] KVM: x86: change PIT discard tick policy Radim Krčmář <rkrcmar@redhat.com> - 2016-02-19 15:50 +0100
Re: [PATCH v2 01/14] KVM: x86: change PIT discard tick policy Paolo Bonzini <pbonzini@redhat.com> - 2016-02-18 19:50 +0100
[PATCH v2 08/14] KVM: x86: remove notifiers from PIT discard policy Radim Krčmář <rkrcmar@redhat.com> - 2016-02-17 20:20 +0100
Re: [PATCH v2 08/14] KVM: x86: remove notifiers from PIT discard policy Paolo Bonzini <pbonzini@redhat.com> - 2016-02-18 19:10 +0100
Re: [PATCH v2 08/14] KVM: x86: remove notifiers from PIT discard policy Paolo Bonzini <pbonzini@redhat.com> - 2016-02-18 19:10 +0100
Re: [PATCH v2 08/14] KVM: x86: remove notifiers from PIT discard policy Radim Krčmář <rkrcmar@redhat.com> - 2016-02-19 16:10 +0100
Re: [PATCH v2 08/14] KVM: x86: remove notifiers from PIT discard policy Paolo Bonzini <pbonzini@redhat.com> - 2016-02-19 16:10 +0100
Re: [PATCH v2 08/14] KVM: x86: remove notifiers from PIT discard policy Radim Krčmář <rkrcmar@redhat.com> - 2016-02-19 16:10 +0100
[PATCH v2 10/14] KVM: x86: refactor kvm_free_pit Radim Krčmář <rkrcmar@redhat.com> - 2016-02-17 20:20 +0100
[PATCH v2 11/14] KVM: x86: remove pit and kvm from kvm_kpit_state Radim Krčmář <rkrcmar@redhat.com> - 2016-02-17 20:20 +0100
[PATCH v2 07/14] KVM: x86: remove unnecessary uses of PIT state lock Radim Krčmář <rkrcmar@redhat.com> - 2016-02-17 20:20 +0100
Re: [PATCH v2 07/14] KVM: x86: remove unnecessary uses of PIT state lock Paolo Bonzini <pbonzini@redhat.com> - 2016-02-18 19:10 +0100
Re: [PATCH v2 07/14] KVM: x86: remove unnecessary uses of PIT state lock Radim Krčmář <rkrcmar@redhat.com> - 2016-02-19 15:50 +0100
[PATCH v2 03/14] KVM: x86: add kvm_pit_reset_reinject Radim Krčmář <rkrcmar@redhat.com> - 2016-02-17 20:30 +0100
Re: [PATCH v2 00/14] KVM: x86: change PIT discard policy and untangle related code Paolo Bonzini <pbonzini@redhat.com> - 2016-02-18 19:20 +0100
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