On Mon, Aug 20, 2018 at 09:47:20AM -0400, Konrad Rzeszutek Wilk wrote:
>On Sun, Aug 19, 2018 at 08:17:45AM +0800, Wei Yang wrote:
>> update_memslots() is only called by __kvm_set_memory_region(), in which
>> change is calculated to indicate the following behavior. With this
>
>What is the 'following behavior' you mention?
Ah, 'following behavior' means what need to do in update_memslots() to
used_slots.
For example, if change equals KVM_MR_CREATE, it means update_memslots()
will add a new slot and used_slots need to increase by one.
With this information, we don't need to do the calculation in
update_memslots() again, but just do an addition.
>
>> information, it is not necessary to do the calculation again in
>> update_memslots().
>>
>> By encoding the number of slot adjustment in the lowest byte of change,
>> the slots->used_slots adjustment is accomplished by one addition.
>>
>> Signed-off-by: Wei Yang <richard.weiyang@xxxxxxxxx>
>> ---
>> include/linux/kvm_host.h | 11 +++++++----
>> virt/kvm/kvm_main.c | 14 ++++----------
>> 2 files changed, 11 insertions(+), 14 deletions(-)
>>
>> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
>> index 4ee7bc548a83..e0ae6cf82c0d 100644
>> --- a/include/linux/kvm_host.h
>> +++ b/include/linux/kvm_host.h
>> @@ -610,12 +610,15 @@ id_to_memslot(struct kvm_memslots *slots, int id)
>> *
>> * Since flags can be changed by some of these operations, the following
>> * differentiation is the best we can do for __kvm_set_memory_region():
>> + *
>> + * Encode the number of slot adjustment in the lowest byte, which will
>> + * be used in update_memslots().
>> */
>> enum kvm_mr_change {
>> - KVM_MR_CREATE,
>> - KVM_MR_DELETE,
>> - KVM_MR_MOVE,
>> - KVM_MR_FLAGS_ONLY,
>> + KVM_MR_CREATE = 0x0001,
>> + KVM_MR_DELETE = 0x00ff,
>> + KVM_MR_MOVE = 0x0000,
>> + KVM_MR_FLAGS_ONLY = 0x0100,
>> };
>>
>> int kvm_set_memory_region(struct kvm *kvm,
>> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
>> index 3d233ebfbee9..5c1911790f25 100644
>> --- a/virt/kvm/kvm_main.c
>> +++ b/virt/kvm/kvm_main.c
>> @@ -801,21 +801,15 @@ static int kvm_create_dirty_bitmap(struct kvm_memory_slot *memslot)
>> * sorted array and known changed memslot position.
>> */
>> static void update_memslots(struct kvm_memslots *slots,
>> - struct kvm_memory_slot *new)
>> + struct kvm_memory_slot *new,
>> + enum kvm_mr_change change)
>> {
>> int id = new->id;
>> int i = slots->id_to_index[id];
>> struct kvm_memory_slot *mslots = slots->memslots;
>>
>> WARN_ON(mslots[i].id != id);
>> - if (!new->npages) {
>> - WARN_ON(!mslots[i].npages);
>> - if (mslots[i].npages)
>> - slots->used_slots--;
>> - } else {
>> - if (!mslots[i].npages)
>> - slots->used_slots++;
>> - }
>> + slots->used_slots += (char)change;
>>
>> while (i < KVM_MEM_SLOTS_NUM - 1 &&
>> new->base_gfn <= mslots[i + 1].base_gfn) {
>> @@ -1050,7 +1044,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
>> memset(&new.arch, 0, sizeof(new.arch));
>> }
>>
>> - update_memslots(slots, &new);
>> + update_memslots(slots, &new, change);
>> old_memslots = install_new_memslots(kvm, as_id, slots);
>>
>> kvm_arch_commit_memory_region(kvm, mem, &old, &new, change);
>> --
>> 2.15.1
>>
--
Wei Yang
Help you, Help me
