diff options
| author | Avi Kivity <avi@redhat.com> | 2010-05-03 16:54:48 +0300 |
|---|---|---|
| committer | Avi Kivity <avi@redhat.com> | 2010-08-01 10:35:37 +0300 |
| commit | d94e1dc9af60e3431a586c3edfbe42d8a0d3932b (patch) | |
| tree | c9ae8e5e69241d51898ab657d0ff48004b5bd4dc | |
| parent | 54b8486f469475d6c8e8aec917b91239a54eb8c8 (diff) | |
KVM: Get rid of KVM_REQ_KICK
KVM_REQ_KICK poisons vcpu->requests by having a bit set during normal
operation. This causes the fast path check for a clear vcpu->requests
to fail all the time, triggering tons of atomic operations.
Fix by replacing KVM_REQ_KICK with a vcpu->guest_mode atomic.
Signed-off-by: Avi Kivity <avi@redhat.com>
| -rw-r--r-- | arch/x86/kvm/x86.c | 17 | ||||
| -rw-r--r-- | include/linux/kvm_host.h | 1 |
2 files changed, 11 insertions, 7 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 63c87adcec4..fc5611b4007 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4604,13 +4604,15 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) if (vcpu->fpu_active) kvm_load_guest_fpu(vcpu); - local_irq_disable(); + atomic_set(&vcpu->guest_mode, 1); + smp_wmb(); - clear_bit(KVM_REQ_KICK, &vcpu->requests); - smp_mb__after_clear_bit(); + local_irq_disable(); - if (vcpu->requests || need_resched() || signal_pending(current)) { - set_bit(KVM_REQ_KICK, &vcpu->requests); + if (!atomic_read(&vcpu->guest_mode) || vcpu->requests + || need_resched() || signal_pending(current)) { + atomic_set(&vcpu->guest_mode, 0); + smp_wmb(); local_irq_enable(); preempt_enable(); r = 1; @@ -4655,7 +4657,8 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) if (hw_breakpoint_active()) hw_breakpoint_restore(); - set_bit(KVM_REQ_KICK, &vcpu->requests); + atomic_set(&vcpu->guest_mode, 0); + smp_wmb(); local_irq_enable(); ++vcpu->stat.exits; @@ -5580,7 +5583,7 @@ void kvm_vcpu_kick(struct kvm_vcpu *vcpu) me = get_cpu(); if (cpu != me && (unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) - if (!test_and_set_bit(KVM_REQ_KICK, &vcpu->requests)) + if (atomic_xchg(&vcpu->guest_mode, 0)) smp_send_reschedule(cpu); put_cpu(); } diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index a0e019769f5..2c62319727e 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -81,6 +81,7 @@ struct kvm_vcpu { int vcpu_id; struct mutex mutex; int cpu; + atomic_t guest_mode; struct kvm_run *run; unsigned long requests; unsigned long guest_debug; |