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authorPaolo Bonzini <pbonzini@redhat.com>2016-10-13 13:10:57 +0200
committerPaolo Bonzini <pbonzini@redhat.com>2016-10-27 11:35:47 +0200
commit58e3948a87e39289aeda5753e9712092c8ca0745 (patch)
treea9b200b62b48ac44c5326c4c9fa95f9bf2ed96a0 /Documentation/virtual/kvm/locking.txt
parent36343f6ea721e003ed11b48a6a05d77a255b3a62 (diff)
KVM: document lock orders
This is long overdue, and not really hard. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <1476357057-17899-1-git-send-email-pbonzini@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'Documentation/virtual/kvm/locking.txt')
-rw-r--r--Documentation/virtual/kvm/locking.txt12
1 files changed, 11 insertions, 1 deletions
diff --git a/Documentation/virtual/kvm/locking.txt b/Documentation/virtual/kvm/locking.txt
index f2491a8c68b4..e5dd9f4d6100 100644
--- a/Documentation/virtual/kvm/locking.txt
+++ b/Documentation/virtual/kvm/locking.txt
@@ -4,7 +4,17 @@ KVM Lock Overview
1. Acquisition Orders
---------------------
-(to be written)
+The acquisition orders for mutexes are as follows:
+
+- kvm->lock is taken outside vcpu->mutex
+
+- kvm->lock is taken outside kvm->slots_lock and kvm->irq_lock
+
+- kvm->slots_lock is taken outside kvm->irq_lock, though acquiring
+ them together is quite rare.
+
+For spinlocks, kvm_lock is taken outside kvm->mmu_lock. Everything
+else is a leaf: no other lock is taken inside the critical sections.
2: Exception
------------