diff options
| author | David Woodhouse <dwmw@amazon.co.uk> | 2024-02-27 11:49:19 +0000 |
|---|---|---|
| committer | Sean Christopherson <seanjc@google.com> | 2024-03-04 16:22:39 -0800 |
| commit | 7a36d680658ba5a0d350f2ad275b97156b8d4333 (patch) | |
| tree | 27817c04b202560167f742c788c6dbaab448030f | |
| parent | 6addfcf27139da1356493f2a440af1252b5b7dbe (diff) | |
KVM: x86/xen: fix recursive deadlock in timer injection
The fast-path timer delivery introduced a recursive locking deadlock
when userspace configures a timer which has already expired and is
delivered immediately. The call to kvm_xen_inject_timer_irqs() can
call to kvm_xen_set_evtchn() which may take kvm->arch.xen.xen_lock,
which is already held in kvm_xen_vcpu_get_attr().
============================================
WARNING: possible recursive locking detected
6.8.0-smp--5e10b4d51d77-drs #232 Tainted: G O
--------------------------------------------
xen_shinfo_test/250013 is trying to acquire lock:
ffff938c9930cc30 (&kvm->arch.xen.xen_lock){+.+.}-{3:3}, at: kvm_xen_set_evtchn+0x74/0x170 [kvm]
but task is already holding lock:
ffff938c9930cc30 (&kvm->arch.xen.xen_lock){+.+.}-{3:3}, at: kvm_xen_vcpu_get_attr+0x38/0x250 [kvm]
Now that the gfn_to_pfn_cache has its own self-sufficient locking, its
callers no longer need to ensure serialization, so just stop taking
kvm->arch.xen.xen_lock from kvm_xen_set_evtchn().
Fixes: 77c9b9dea4fb ("KVM: x86/xen: Use fast path for Xen timer delivery")
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>
Link: https://lore.kernel.org/r/20240227115648.3104-6-dwmw2@infradead.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
| -rw-r--r-- | arch/x86/kvm/xen.c | 4 |
1 files changed, 0 insertions, 4 deletions
diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c index 54c4ced96b69..f65b35a05d91 100644 --- a/arch/x86/kvm/xen.c +++ b/arch/x86/kvm/xen.c @@ -1862,8 +1862,6 @@ static int kvm_xen_set_evtchn(struct kvm_xen_evtchn *xe, struct kvm *kvm) mm_borrowed = true; } - mutex_lock(&kvm->arch.xen.xen_lock); - /* * It is theoretically possible for the page to be unmapped * and the MMU notifier to invalidate the shared_info before @@ -1891,8 +1889,6 @@ static int kvm_xen_set_evtchn(struct kvm_xen_evtchn *xe, struct kvm *kvm) srcu_read_unlock(&kvm->srcu, idx); } while(!rc); - mutex_unlock(&kvm->arch.xen.xen_lock); - if (mm_borrowed) kthread_unuse_mm(kvm->mm); |