From patchwork Tue Jun 23 19:35:39 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sean Christopherson X-Patchwork-Id: 11621577 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 6F6D9161F for ; Tue, 23 Jun 2020 19:35:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5EDAF20C09 for ; Tue, 23 Jun 2020 19:35:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387513AbgFWTfq (ORCPT ); Tue, 23 Jun 2020 15:35:46 -0400 Received: from mga11.intel.com ([192.55.52.93]:11007 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387430AbgFWTfo (ORCPT ); Tue, 23 Jun 2020 15:35:44 -0400 IronPort-SDR: sJ9sRrvxb1h5Okc9pcBYB6agzuUxgWFnBl5k//utyzCFXv1OdBKibJm+1+i3gUy5SWrC7W9i6J im2bQ1BqbqXg== X-IronPort-AV: E=McAfee;i="6000,8403,9661"; a="142430969" X-IronPort-AV: E=Sophos;i="5.75,272,1589266800"; d="scan'208";a="142430969" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Jun 2020 12:35:44 -0700 IronPort-SDR: f/IL09ce9Xl12I9sC84qWOGB+ALwlnlDkcqdbVGwKzExiEQfaqkLOU6xbOyYA/jWnWsc4Xx629 B2L/gsVdejgQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.75,272,1589266800"; d="scan'208";a="263428289" Received: from sjchrist-coffee.jf.intel.com ([10.54.74.152]) by fmsmga007.fm.intel.com with ESMTP; 23 Jun 2020 12:35:43 -0700 From: Sean Christopherson To: Paolo Bonzini Cc: Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 1/4] KVM: x86/mmu: Don't put invalid SPs back on the list of active pages Date: Tue, 23 Jun 2020 12:35:39 -0700 Message-Id: <20200623193542.7554-2-sean.j.christopherson@intel.com> X-Mailer: git-send-email 2.26.0 In-Reply-To: <20200623193542.7554-1-sean.j.christopherson@intel.com> References: <20200623193542.7554-1-sean.j.christopherson@intel.com> MIME-Version: 1.0 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Delete a shadow page from the invalidation list instead of throwing it back on the list of active pages when it's a root shadow page with active users. Invalid active root pages will be explicitly freed by mmu_free_root_page() when the root_count hits zero, i.e. they don't need to be put on the active list to avoid leakage. Use sp->role.invalid to detect that a shadow page has already been zapped, i.e. is not on a list. WARN if an invalid page is encountered when zapping pages, as it should now be impossible. Signed-off-by: Sean Christopherson --- arch/x86/kvm/mmu/mmu.c | 28 ++++++++++++++++++++-------- 1 file changed, 20 insertions(+), 8 deletions(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 3dd0af7e7515..8e7df4ed4b55 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -2757,10 +2757,23 @@ static bool __kvm_mmu_prepare_zap_page(struct kvm *kvm, if (!sp->root_count) { /* Count self */ (*nr_zapped)++; - list_move(&sp->link, invalid_list); + + /* + * Already invalid pages (previously active roots) are not on + * the active page list. See list_del() in the "else" case of + * !sp->root_count. + */ + if (sp->role.invalid) + list_add(&sp->link, invalid_list); + else + list_move(&sp->link, invalid_list); kvm_mod_used_mmu_pages(kvm, -1); } else { - list_move(&sp->link, &kvm->arch.active_mmu_pages); + /* + * Remove the active root from the active page list, the root + * will be explicitly freed when the root_count hits zero. + */ + list_del(&sp->link); /* * Obsolete pages cannot be used on any vCPUs, see the comment @@ -5727,12 +5740,11 @@ static void kvm_zap_obsolete_pages(struct kvm *kvm) break; /* - * Skip invalid pages with a non-zero root count, zapping pages - * with a non-zero root count will never succeed, i.e. the page - * will get thrown back on active_mmu_pages and we'll get stuck - * in an infinite loop. + * Invalid pages should never land back on the list of active + * pages. Skip the bogus page, otherwise we'll get stuck in an + * infinite loop if the page gets put back on the list (again). */ - if (sp->role.invalid && sp->root_count) + if (WARN_ON(sp->role.invalid)) continue; /* @@ -6010,7 +6022,7 @@ void kvm_mmu_zap_all(struct kvm *kvm) spin_lock(&kvm->mmu_lock); restart: list_for_each_entry_safe(sp, node, &kvm->arch.active_mmu_pages, link) { - if (sp->role.invalid && sp->root_count) + if (WARN_ON(sp->role.invalid)) continue; if (__kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list, &ign)) goto restart;