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authorMarcelo Tosatti <mtosatti@redhat.com>2009-06-17 10:53:47 -0300
committerAvi Kivity <avi@redhat.com>2009-06-28 14:10:29 +0300
commit84261923d3dddb766736023bead6fa07b7e218d5 (patch)
tree23a0c4af14dd9c548c5bcb457c74fdd980e2312e /virt
parent29a4b9333bf9ffef12b3dd7cbf2e3dbe01152968 (diff)
downloadlinux-linaro-stable-84261923d3dddb766736023bead6fa07b7e218d5.tar.gz
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>
Diffstat (limited to 'virt')
-rw-r--r--virt/kvm/kvm_main.c3
1 files changed, 3 insertions, 0 deletions
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);