On large memory guests it has been observed that creating a memslot for a very large range can take noticeable amount of time. Investigation showed that the time is spent walking the rmaps to update existing sptes to remove write access or set/clear dirty bits to support dirty logging. These rmap walks are unnecessary when creating or moving a memslot. A newly created memslot will not have any existing mappings, and the existing mappings of a moved memslot will have been invalidated and flushed. Any mappings established once the new/moved memslot becomes visible will be set using the properties of the new slot. Signed-off-by: Anthony Yznaga <anthony.yznaga@xxxxxxxxxx> --- arch/x86/kvm/x86.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 23fd888e52ee..d211c8ced6bb 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -10138,7 +10138,7 @@ void kvm_arch_commit_memory_region(struct kvm *kvm, * * FIXME: const-ify all uses of struct kvm_memory_slot. */ - if (change != KVM_MR_DELETE) + if (change == KVM_MR_FLAGS_ONLY) kvm_mmu_slot_apply_flags(kvm, (struct kvm_memory_slot *) new); /* Free the arrays associated with the old memslot. */ -- 2.13.3
