On 07/06/2017 04:45 PM, Christian Borntraeger wrote:
> we access the memslots array via srcu. Mark it as such and
> use the right access functions also for the freeing of
> memory slots.
>
> Found by sparse:
> ./include/linux/kvm_host.h:565:16: error: incompatible types in
> comparison expression (different address spaces)
>
> Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
> ---
> include/linux/kvm_host.h | 2 +-
> virt/kvm/kvm_main.c | 4 ++--
> 2 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index bcd37b8..7c32905 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -390,7 +390,7 @@ struct kvm {
> spinlock_t mmu_lock;
> struct mutex slots_lock;
> struct mm_struct *mm; /* userspace tied to this vm */
> - struct kvm_memslots *memslots[KVM_ADDRESS_SPACE_NUM];
> + struct kvm_memslots __rcu *memslots[KVM_ADDRESS_SPACE_NUM];
> struct kvm_vcpu *vcpus[KVM_MAX_VCPUS];
>
> /*
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index fc2d583..d4418fa 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -707,7 +707,7 @@ static struct kvm *kvm_create_vm(unsigned long type)
> for (i = 0; i < KVM_NR_BUSES; i++)
> kfree(kvm->buses[i]);
> for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++)
> - kvm_free_memslots(kvm, kvm->memslots[i]);
> + kvm_free_memslots(kvm, rcu_access_pointer(kvm->memslots[i]));
should these rather be rcu_dereference_protected ?
> kvm_arch_free_vm(kvm);
> mmdrop(current->mm);
> return ERR_PTR(r);
> @@ -753,7 +753,7 @@ static void kvm_destroy_vm(struct kvm *kvm)
> kvm_arch_destroy_vm(kvm);
> kvm_destroy_devices(kvm);
> for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++)
> - kvm_free_memslots(kvm, kvm->memslots[i]);
> + kvm_free_memslots(kvm, rcu_access_pointer(kvm->memslots[i]));
> cleanup_srcu_struct(&kvm->irq_srcu);
> cleanup_srcu_struct(&kvm->srcu);
> kvm_arch_free_vm(kvm);
>
