Messages in this thread Patch in this message |  | | Subject | Re: [PATCH RFC 2/2] KVM: RCU protected dynamic vcpus array | From | David Hildenbrand <> | Date | Thu, 17 Aug 2017 13:14:27 +0200 |
| |
> atomic_set(&kvm->online_vcpus, 0); > mutex_unlock(&kvm->lock); > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > index c8df733eed41..eb9fb5b493ac 100644 > --- a/include/linux/kvm_host.h > +++ b/include/linux/kvm_host.h > @@ -386,12 +386,17 @@ struct kvm_memslots { > int used_slots; > }; > > +struct kvm_vcpus { > + u32 online; > + struct kvm_vcpu *array[];
On option could be to simply chunk it:
+struct kvm_vcpus { + struct kvm_vcpu vcpus[32]; +}; + /* * Note: * memslots are not sorted by id anymore, please use id_to_memslot() @@ -391,7 +395,7 @@ struct kvm { struct mutex slots_lock; struct mm_struct *mm; /* userspace tied to this vm */ struct kvm_memslots __rcu *memslots[KVM_ADDRESS_SPACE_NUM]; - struct kvm_vcpu *vcpus[KVM_MAX_VCPUS]; + struct kvm_vcpus vcpus[(KVM_MAX_VCPUS + 31) / 32];
/* * created_vcpus is protected by kvm->lock, and is incremented @@ -483,12 +487,14 @@ static inline struct kvm_io_bus *kvm_get_bus(struct kvm *kvm, enum kvm_bus idx)
1. make nobody access kvm->vcpus directly (factor out) 2. allocate next chunk if necessary when creating a VCPU and store pointer using WRITE_ONCE 3. use READ_ONCE to test for availability of the current chunk
kvm_for_each_vcpu just has to use READ_ONCE to access/test for the right chunk. Pointers never get invalid. No RCU needed. Sleeping in the loop is possible.
--
Thanks,
David
|  |