From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: [PATCH] KVM: Start lock documentation Date: Wed, 09 Feb 2011 15:11:28 +0100 Message-ID: <4D52A090.5010308@siemens.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Cc: kvm To: Avi Kivity , Marcelo Tosatti Return-path: Received: from david.siemens.de ([192.35.17.14]:16163 "EHLO david.siemens.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755009Ab1BIOLm (ORCPT ); Wed, 9 Feb 2011 09:11:42 -0500 Sender: kvm-owner@vger.kernel.org List-ID: 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 --- 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