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| author | Marcelo Tosatti <mtosatti@redhat.com> | 2009-06-17 10:53:47 -0300 |
|---|---|---|
| committer | Avi Kivity <avi@redhat.com> | 2009-06-28 14:10:29 +0300 |
| commit | 84261923d3dddb766736023bead6fa07b7e218d5 (patch) | |
| tree | 23a0c4af14dd9c548c5bcb457c74fdd980e2312e | |
| parent | 29a4b9333bf9ffef12b3dd7cbf2e3dbe01152968 (diff) | |
| download | linux-84261923d3dddb766736023bead6fa07b7e218d5.tar.bz2 | |
KVM: protect concurrent make_all_cpus_request
make_all_cpus_request contains a race condition which can
trigger false request completed status, as follows:
CPU0 CPU1
if (test_and_set_bit(req,&vcpu->requests))
.... if (test_and_set_bit(req,&vcpu->requests))
.. return
proceed to smp_call_function_many(wait=1)
Use a spinlock to serialize concurrent CPUs.
Cc: stable@kernel.org
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
| -rw-r--r-- | include/linux/kvm_host.h | 1 | ||||
| -rw-r--r-- | virt/kvm/kvm_main.c | 3 |
2 files changed, 4 insertions, 0 deletions
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index aacc5449f586..16713dc672e4 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -125,6 +125,7 @@ struct kvm_kernel_irq_routing_entry { struct kvm { struct mutex lock; /* protects the vcpus array and APIC accesses */ spinlock_t mmu_lock; + spinlock_t requests_lock; struct rw_semaphore slots_lock; struct mm_struct *mm; /* userspace tied to this vm */ int nmemslots; diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 013a5b3e9f75..2884baf1d5f9 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -746,6 +746,7 @@ static bool make_all_cpus_request(struct kvm *kvm, unsigned int req) cpumask_clear(cpus); me = get_cpu(); + spin_lock(&kvm->requests_lock); for (i = 0; i < KVM_MAX_VCPUS; ++i) { vcpu = kvm->vcpus[i]; if (!vcpu) @@ -762,6 +763,7 @@ static bool make_all_cpus_request(struct kvm *kvm, unsigned int req) smp_call_function_many(cpus, ack_flush, NULL, 1); else called = false; + spin_unlock(&kvm->requests_lock); put_cpu(); free_cpumask_var(cpus); return called; @@ -982,6 +984,7 @@ static struct kvm *kvm_create_vm(void) kvm->mm = current->mm; atomic_inc(&kvm->mm->mm_count); spin_lock_init(&kvm->mmu_lock); + spin_lock_init(&kvm->requests_lock); kvm_io_bus_init(&kvm->pio_bus); mutex_init(&kvm->lock); kvm_io_bus_init(&kvm->mmio_bus); |