diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/virt/kvm/locking.rst | 19 |
1 files changed, 10 insertions, 9 deletions
diff --git a/Documentation/virt/kvm/locking.rst b/Documentation/virt/kvm/locking.rst index 0f6067d13622..1147836742cc 100644 --- a/Documentation/virt/kvm/locking.rst +++ b/Documentation/virt/kvm/locking.rst @@ -9,6 +9,8 @@ KVM Lock Overview The acquisition orders for mutexes are as follows: +- cpus_read_lock() is taken outside kvm_lock + - kvm->lock is taken outside vcpu->mutex - kvm->lock is taken outside kvm->slots_lock and kvm->irq_lock @@ -225,15 +227,10 @@ time it will be set using the Dirty tracking mechanism described above. :Type: mutex :Arch: any :Protects: - vm_list - -``kvm_count_lock`` -^^^^^^^^^^^^^^^^^^ - -:Type: raw_spinlock_t -:Arch: any -:Protects: - hardware virtualization enable/disable -:Comment: 'raw' because hardware enabling/disabling must be atomic /wrt - migration. + - kvm_usage_count + - hardware virtualization enable/disable +:Comment: KVM also disables CPU hotplug via cpus_read_lock() during + enable/disable. ``kvm->mn_invalidate_lock`` ^^^^^^^^^^^^^^^^^^^^^^^^^^^ @@ -297,3 +294,7 @@ time it will be set using the Dirty tracking mechanism described above. :Type: mutex :Arch: x86 :Protects: loading a vendor module (kvm_amd or kvm_intel) +:Comment: Exists because using kvm_lock leads to deadlock. cpu_hotplug_lock is + taken outside of kvm_lock, e.g. in KVM's CPU online/offline callbacks, and + many operations need to take cpu_hotplug_lock when loading a vendor module, + e.g. updating static calls. |