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SubjectRe: [PATCH v2 6/6] KVM: introduce a table to map slot id to index in memslots arry
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On Fri, 2011-11-18 at 17:20 +0800, Xiao Guangrong wrote:
> The operation of getting dirty log is frequency When framebuffer-based
> displays are used(for example, Xwindow), so, we introduce a mapping table
> to speed up id_to_memslot()
>
> Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
> ---
> include/linux/kvm_host.h | 13 +++++++------
> virt/kvm/kvm_main.c | 7 ++++++-
> 2 files changed, 13 insertions(+), 7 deletions(-)
>
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index 83b396a..fbf66eb 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -238,6 +238,8 @@ struct kvm_irq_routing_table {};
> struct kvm_memslots {
> u64 generation;
> struct kvm_memory_slot memslots[KVM_MEM_SLOTS_NUM];
> + /* The mapping table from slot id to the index in memslots[]. */
> + int id_to_index[KVM_MEM_SLOTS_NUM];
> };
>
> struct kvm {
> @@ -340,14 +342,13 @@ static inline struct kvm_memslots *kvm_memslots(struct kvm *kvm)
> static inline struct kvm_memory_slot *
> id_to_memslot(struct kvm_memslots *slots, int id)
> {
> - int i;
> + int index = slots->id_to_index[id];
> + struct kvm_memory_slot *slot;
>
> - for (i = 0; i < KVM_MEM_SLOTS_NUM; i++)
> - if (slots->memslots[i].id == id)
> - return &slots->memslots[i];
> + slot = &slots->memslots[index];
>
> - WARN_ON(1);
> - return NULL;
> + WARN_ON(slot->id != id);
> + return slot;
> }

If we didn't find the right memslot we shouldn't be returning a wrong
one, we should be failing.

--

Sasha.



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