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authorMichael S. Tsirkin <mst@redhat.com>2012-09-16 11:50:30 +0300
committerMarcelo Tosatti <mtosatti@redhat.com>2012-09-17 13:46:32 -0300
commit9fc77441e5e1bf80b794cc546d2243ee9f4afb75 (patch)
tree4661976f4fea7606a54b3f5276c0ecb45760979c /virt
parent7454766f7bead388251aedee35a478356a7f4e72 (diff)
downloadvexpress-lsk-9fc77441e5e1bf80b794cc546d2243ee9f4afb75.tar.gz
KVM: make processes waiting on vcpu mutex killable
vcpu mutex can be held for unlimited time so taking it with mutex_lock on an ioctl is wrong: one process could be passed a vcpu fd and call this ioctl on the vcpu used by another process, it will then be unkillable until the owner exits. Call mutex_lock_killable instead and return status. Note: mutex_lock_interruptible would be even nicer, but I am not sure all users are prepared to handle EINTR from these ioctls. They might misinterpret it as an error. Cleanup paths expect a vcpu that can't be used by any userspace so this will always succeed - catch bugs by calling BUG_ON. Catch callers that don't check return state by adding __must_check. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Diffstat (limited to 'virt')
-rw-r--r--virt/kvm/kvm_main.c10
1 files changed, 7 insertions, 3 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 4fe02d90081..cc3f6dc506e 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -131,11 +131,12 @@ bool kvm_is_mmio_pfn(pfn_t pfn)
/*
* Switches to specified vcpu, until a matching vcpu_put()
*/
-void vcpu_load(struct kvm_vcpu *vcpu)
+int vcpu_load(struct kvm_vcpu *vcpu)
{
int cpu;
- mutex_lock(&vcpu->mutex);
+ if (mutex_lock_killable(&vcpu->mutex))
+ return -EINTR;
if (unlikely(vcpu->pid != current->pids[PIDTYPE_PID].pid)) {
/* The thread running this VCPU changed. */
struct pid *oldpid = vcpu->pid;
@@ -148,6 +149,7 @@ void vcpu_load(struct kvm_vcpu *vcpu)
preempt_notifier_register(&vcpu->preempt_notifier);
kvm_arch_vcpu_load(vcpu, cpu);
put_cpu();
+ return 0;
}
void vcpu_put(struct kvm_vcpu *vcpu)
@@ -1891,7 +1893,9 @@ static long kvm_vcpu_ioctl(struct file *filp,
#endif
- vcpu_load(vcpu);
+ r = vcpu_load(vcpu);
+ if (r)
+ return r;
switch (ioctl) {
case KVM_RUN:
r = -EINVAL;