Re: [patch 3/3] KVM: move postcommit flush to x86, as mmio sptes are x86 specific

Takuya Yoshikawa
2012-08-27T14:41:13Z

On Fri, 24 Aug 2012 15:54:59 -0300
Marcelo Tosatti <mtosatti@redhat.com> wrote:

> Other arches do not need this.
>
> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
>
> Index: kvm/arch/x86/kvm/x86.c
> ===================================================================
> --- kvm.orig/arch/x86/kvm/x86.c
> +++ kvm/arch/x86/kvm/x86.c
> @@ -6455,6 +6455,14 @@ void kvm_arch_commit_memory_region(struc
> kvm_mmu_change_mmu_pages(kvm, nr_mmu_pages);
> kvm_mmu_slot_remove_write_access(kvm, mem->slot);
> spin_unlock(&kvm->mmu_lock);
> + /*
> + * If the new memory slot is created, we need to clear all
> + * mmio sptes.
> + */
> + if (old.npages == 0 && npages) {
> + kvm_mmu_zap_all(kvm);
> + kvm_reload_remote_mmus(kvm);
> + }
> }

Any explanation why (old.base_gfn != new.base_gfn) case can be
omitted?

Takuya

>
> void kvm_arch_flush_shadow_all(struct kvm *kvm)
> Index: kvm/virt/kvm/kvm_main.c
> ===================================================================
> --- kvm.orig/virt/kvm/kvm_main.c
> +++ kvm/virt/kvm/kvm_main.c
> @@ -849,13 +849,6 @@ int __kvm_set_memory_region(struct kvm *
>
> kvm_arch_commit_memory_region(kvm, mem, old, user_alloc);
>
> - /*
> - * If the new memory slot is created, we need to clear all
> - * mmio sptes.
> - */
> - if (npages && old.base_gfn != mem->guest_phys_addr >> PAGE_SHIFT)
> - kvm_arch_flush_shadow_all(kvm);
> -
> kvm_free_physmem_slot(&old, &new);
> kfree(old_memslots);