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| author | Sean Christopherson <seanjc@google.com> | 2025-02-01 04:38:17 +0300 |
|---|---|---|
| committer | Sean Christopherson <seanjc@google.com> | 2025-02-12 21:45:54 +0300 |
| commit | d9c5ed0a9b529ee1103a4b68cec86112b26380e0 (patch) | |
| tree | 6eb5f09d949bfca2f17266aecf456424787c1efd | |
| parent | a64dcfb451e254085a7daee5fe51bf22959d52d3 (diff) | |
| download | linux-d9c5ed0a9b529ee1103a4b68cec86112b26380e0.tar.xz | |
KVM: x86: Don't take kvm->lock when iterating over vCPUs in suspend notifier
When queueing vCPU PVCLOCK updates in response to SUSPEND or HIBERNATE,
don't take kvm->lock as doing so can trigger a largely theoretical
deadlock, it is perfectly safe to iterate over the xarray of vCPUs without
holding kvm->lock, and kvm->lock doesn't protect kvm_set_guest_paused() in
any way (pv_time.active and pvclock_set_guest_stopped_request are
protected by vcpu->mutex, not kvm->lock).
Reported-by: syzbot+352e553a86e0d75f5120@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/677c0f36.050a0220.3b3668.0014.GAE@google.com
Fixes: 7d62874f69d7 ("kvm: x86: implement KVM PM-notifier")
Reviewed-by: Paul Durrant <paul@xen.org>
Link: https://lore.kernel.org/r/20250201013827.680235-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
| -rw-r--r-- | arch/x86/kvm/x86.c | 2 |
1 files changed, 0 insertions, 2 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 8e77e61d4fbd..b83d58f9f0b4 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -6907,7 +6907,6 @@ static int kvm_arch_suspend_notifier(struct kvm *kvm) unsigned long i; int ret = 0; - mutex_lock(&kvm->lock); kvm_for_each_vcpu(i, vcpu, kvm) { if (!vcpu->arch.pv_time.active) continue; @@ -6919,7 +6918,6 @@ static int kvm_arch_suspend_notifier(struct kvm *kvm) break; } } - mutex_unlock(&kvm->lock); return ret ? NOTIFY_BAD : NOTIFY_DONE; } |