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
Start with one dependency chain and two locks.
Signed-off-by: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>
---
Documentation/kvm/locking.txt | 30 ++++++++++++++++++++++++++++++
1 files changed, 30 insertions(+), 0 deletions(-)
create mode 100644 Documentation/kvm/locking.txt
diff --git a/Documentation/kvm/locking.txt b/Documentation/kvm/locking.txt
new file mode 100644
index 0000000..23f9092
--- /dev/null
+++ b/Documentation/kvm/locking.txt
@@ -0,0 +1,30 @@
+KVM Lock Overview
+=================
+
+1. Acquisition Orders
+---------------------
+
+kvm_lock
++-> kvm::srcu / kvm::lock
+ +-> kvm::slots_lock
+ +-> kvm::mmu_lock
+...
+
+
+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.
--
1.7.1
--
To unsubscribe from this list: send the line "unsubscribe kvm" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
