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| author | Michael S. Tsirkin <mst@redhat.com> | 2012-09-16 11:50:30 +0300 |
|---|---|---|
| committer | Marcelo Tosatti <mtosatti@redhat.com> | 2012-09-17 13:46:32 -0300 |
| commit | 9fc77441e5e1bf80b794cc546d2243ee9f4afb75 (patch) | |
| tree | 4661976f4fea7606a54b3f5276c0ecb45760979c /virt | |
| parent | 7454766f7bead388251aedee35a478356a7f4e72 (diff) | |
| download | lwn-9fc77441e5e1bf80b794cc546d2243ee9f4afb75.tar.gz lwn-9fc77441e5e1bf80b794cc546d2243ee9f4afb75.zip | |
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.c | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 4fe02d900810..cc3f6dc506e4 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; |