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| author | Xiao Guangrong <xiaoguangrong@cn.fujitsu.com> | 2011-01-12 15:41:22 +0800 |
|---|---|---|
| committer | Marcelo Tosatti <mtosatti@redhat.com> | 2011-03-17 13:08:26 -0300 |
| commit | 3cba41307a2b1344ab8c1b9f55202d1e9d7bf81b (patch) | |
| tree | 87191d63557cc722906ceaec98a1f8f148cf1fcc | |
| parent | 6b7e2d0991489559a1df4500d77f7b76c4607ed0 (diff) | |
| download | lwn-3cba41307a2b1344ab8c1b9f55202d1e9d7bf81b.tar.gz lwn-3cba41307a2b1344ab8c1b9f55202d1e9d7bf81b.zip | |
KVM: make make_all_cpus_request() lockless
Now, we have 'vcpu->mode' to judge whether need to send ipi to other
cpus, this way is very exact, so checking request bit is needless,
then we can drop the spinlock let it's collateral
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
| -rw-r--r-- | include/linux/kvm_host.h | 6 | ||||
| -rw-r--r-- | virt/kvm/kvm_main.c | 9 |
2 files changed, 3 insertions, 12 deletions
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index b99eacd988ab..c8dee22b1945 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -224,7 +224,6 @@ struct kvm_memslots { struct kvm { spinlock_t mmu_lock; - raw_spinlock_t requests_lock; struct mutex slots_lock; struct mm_struct *mm; /* userspace tied to this vm */ struct kvm_memslots *memslots; @@ -731,11 +730,6 @@ static inline void kvm_make_request(int req, struct kvm_vcpu *vcpu) set_bit(req, &vcpu->requests); } -static inline bool kvm_make_check_request(int req, struct kvm_vcpu *vcpu) -{ - return test_and_set_bit(req, &vcpu->requests); -} - static inline bool kvm_check_request(int req, struct kvm_vcpu *vcpu) { if (test_bit(req, &vcpu->requests)) { diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 19209f849cf7..4856a7dcbd7f 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -165,11 +165,9 @@ static bool make_all_cpus_request(struct kvm *kvm, unsigned int req) zalloc_cpumask_var(&cpus, GFP_ATOMIC); - raw_spin_lock(&kvm->requests_lock); - me = smp_processor_id(); + me = get_cpu(); kvm_for_each_vcpu(i, vcpu, kvm) { - if (kvm_make_check_request(req, vcpu)) - continue; + kvm_make_request(req, vcpu); cpu = vcpu->cpu; /* Set ->requests bit before we read ->mode */ @@ -185,7 +183,7 @@ static bool make_all_cpus_request(struct kvm *kvm, unsigned int req) smp_call_function_many(cpus, ack_flush, NULL, 1); else called = false; - raw_spin_unlock(&kvm->requests_lock); + put_cpu(); free_cpumask_var(cpus); return called; } @@ -468,7 +466,6 @@ static struct kvm *kvm_create_vm(void) kvm->mm = current->mm; atomic_inc(&kvm->mm->mm_count); spin_lock_init(&kvm->mmu_lock); - raw_spin_lock_init(&kvm->requests_lock); kvm_eventfd_init(kvm); mutex_init(&kvm->lock); mutex_init(&kvm->irq_lock); |