diff options
Diffstat (limited to 'Documentation/virtual/kvm/locking.txt')
| -rw-r--r-- | Documentation/virtual/kvm/locking.txt | 23 |
1 files changed, 19 insertions, 4 deletions
diff --git a/Documentation/virtual/kvm/locking.txt b/Documentation/virtual/kvm/locking.txt index 41b7ac9884b..d68af4dc300 100644 --- a/Documentation/virtual/kvm/locking.txt +++ b/Documentation/virtual/kvm/locking.txt @@ -112,7 +112,7 @@ The Dirty bit is lost in this case. In order to avoid this kind of issue, we always treat the spte as "volatile" if it can be updated out of mmu-lock, see spte_has_volatile_bits(), it means, -the spte is always atomicly updated in this case. +the spte is always atomically updated in this case. 3): flush tlbs due to spte updated If the spte is updated from writable to readonly, we should flush all TLBs, @@ -125,17 +125,21 @@ be flushed caused by this reason in mmu_spte_update() since this is a common function to update spte (present -> present). Since the spte is "volatile" if it can be updated out of mmu-lock, we always -atomicly update the spte, the race caused by fast page fault can be avoided, +atomically update the spte, the race caused by fast page fault can be avoided, See the comments in spte_has_volatile_bits() and mmu_spte_update(). 3. Reference ------------ Name: kvm_lock -Type: raw_spinlock +Type: spinlock_t Arch: any Protects: - vm_list - - hardware virtualization enable/disable + +Name: 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. @@ -151,3 +155,14 @@ Type: spinlock_t Arch: any Protects: -shadow page/shadow tlb entry Comment: it is a spinlock since it is used in mmu notifier. + +Name: kvm->srcu +Type: srcu lock +Arch: any +Protects: - kvm->memslots + - kvm->buses +Comment: The srcu read lock must be held while accessing memslots (e.g. + when using gfn_to_* functions) and while accessing in-kernel + MMIO/PIO address->device structure mapping (kvm->buses). + The srcu index can be stored in kvm_vcpu->srcu_idx per vcpu + if it is needed by multiple functions. |