KVM: MMU: reduce KVM_REQ_MMU_RELOAD when root page is zapped

Quote Gleb's mail: | why don't we check for sp->role.invalid in | kvm_mmu_prepare_zap_page before calling kvm_reload_remote_mmus()? and | Actually we can add check for is_obsolete_sp() there too since | kvm_mmu_invalidate_all_pages() already calls kvm_reload_remote_mmus() | after incrementing mmu_valid_gen. [ Xiao: add some comments and the check of is_obsolete_sp() ] Signed-off-by: Gleb Natapov <[email protected]> Signed-off-by: Xiao Guangrong <[email protected]> Reviewed-by: Marcelo Tosatti <[email protected]> Signed-off-by: Gleb Natapov <[email protected]>
josf · Jun 5, 2013 · 05988d7 · 05988d7
1 parent 365c886
commit 05988d7
Showing 1 changed file with 7 additions and 1 deletion.
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
@@ -2108,7 +2108,13 @@ static int kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp,
 		kvm_mod_used_mmu_pages(kvm, -1);
 	} else {
 		list_move(&sp->link, &kvm->arch.active_mmu_pages);
-		kvm_reload_remote_mmus(kvm);
+
+		/*
+		 * The obsolete pages can not be used on any vcpus.
+		 * See the comments in kvm_mmu_invalidate_zap_all_pages().
+		 */
+		if (!sp->role.invalid && !is_obsolete_sp(kvm, sp))
+			kvm_reload_remote_mmus(kvm);
 	}
 
 	sp->role.invalid = 1;