Re: [RFC PATCH 9/9] kvm_main.c: handle atomic memslot update

Yang, Weijiang
2022-09-13T02:31:10Z

On 9/9/2022 6:45 PM, Emanuele Giuseppe Esposito wrote:
> When kvm_vm_ioctl_set_memory_region_list() is invoked, we need
> to make sure that all memslots are updated in the inactive list
> and then swap (preferreably only once) the lists, so that all
> changes are visible immediately.
[...]
> +static int kvm_vm_ioctl_set_memory_region_list(struct kvm *kvm,
> + struct kvm_userspace_memory_region_list *list,
> + struct kvm_userspace_memory_region_entry __user *mem_arg)
> +{
> + struct kvm_userspace_memory_region_entry *mem, *m_iter;
> + struct kvm_userspace_memory_region *mem_region;
> + struct kvm_internal_memory_region_list *batch, *b_iter;
> + int i, r = 0;
> + bool *as_to_swap;
> +
> + /* TODO: limit the number of mem to a max? */
> +
> + if (!list->nent)
> + return r;
> +
> + mem = vmemdup_user(mem_arg, array_size(sizeof(*mem), list->nent));
> + if (IS_ERR(mem)) {
> + r = PTR_ERR(mem);
> + goto out;
> + }

IMO, it's more natural to dup the user memory at the first place, i.e.,
kvm_vm_ioctl,

it also makes the outlets shorter. …