From 38a778aa1899b9c6cf3e300a02782c9b78c547ab Mon Sep 17 00:00:00 2001
From: Jan Kiszka <jan.kiszka@siemens.com>
Date: Wed, 9 Feb 2011 15:11:28 +0100
Subject: [PATCH] KVM: Start lock documentation
The goal of this document shall be
- overview of all locks used in KVM core
- provide details on the scope of each lock
- explain the lock type, specifically of a raw spin locks
- provide a lock ordering guide
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
---
Documentation/kvm/locking.txt | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)
create mode 100644 Documentation/kvm/locking.txt
diff --git a/Documentation/kvm/locking.txt b/Documentation/kvm/locking.txt
new file mode 100644
index 000000000000..3b4cd3bf5631
--- /dev/null
+++ b/Documentation/kvm/locking.txt
@@ -0,0 +1,25 @@
+KVM Lock Overview
+=================
+
+1. Acquisition Orders
+---------------------
+
+(to be written)
+
+2. Reference
+------------
+
+Name: kvm_lock
+Type: raw_spinlock
+Arch: any
+Protects: - vm_list
+ - hardware virtualization enable/disable
+Comment: 'raw' because hardware enabling/disabling must be atomic /wrt
+ migration.
+
+Name: kvm_arch::tsc_write_lock
+Type: raw_spinlock
+Arch: x86
+Protects: - kvm_arch::{last_tsc_write,last_tsc_nsec,last_tsc_offset}
+ - tsc offset in vmcb
+Comment: 'raw' because updating the tsc offsets must not be preempted.
--
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