Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1032359AbbKFHMD (ORCPT ); Fri, 6 Nov 2015 02:12:03 -0500 Received: from tama500.ecl.ntt.co.jp ([129.60.39.148]:33445 "EHLO tama500.ecl.ntt.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1032062AbbKFHMA (ORCPT ); Fri, 6 Nov 2015 02:12:00 -0500 Date: Fri, 6 Nov 2015 16:25:01 +0900 From: Takuya Yoshikawa To: pbonzini@redhat.com Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 5/5] KVM: x86: MMU: Consolidate WARN_ON/BUG_ON checks for reverse-mapped sptes Message-Id: <20151106162501.e97c5a05063625ed1a266553@lab.ntt.co.jp> In-Reply-To: <20151106162016.6924957f7e227e52a345b061@lab.ntt.co.jp> References: <20151106162016.6924957f7e227e52a345b061@lab.ntt.co.jp> X-Mailer: Sylpheed 3.4.2 (GTK+ 2.24.28; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4372 Lines: 130 At some call sites of rmap_get_first() and rmap_get_next(), BUG_ON is placed right after the call to detect unrelated sptes which should not be found in the reverse-mapping list. Move this check in rmap_get_first/next() so that all call sites, not just the users of the for_each_rmap_spte() macro, will be checked the same way. In addition, change the BUG_ON to WARN_ON since killing the whole host is the last thing that KVM should try. One thing to keep in mind is that kvm_mmu_unlink_parents() also uses rmap_get_first() to handle parent sptes. The change will not break it because parent sptes are present, at least until drop_parent_pte() actually unlinks them, and not mmio-sptes. Signed-off-by: Takuya Yoshikawa --- Documentation/virtual/kvm/mmu.txt | 4 ++-- arch/x86/kvm/mmu.c | 31 ++++++++++++++++++++++--------- 2 files changed, 24 insertions(+), 11 deletions(-) diff --git a/Documentation/virtual/kvm/mmu.txt b/Documentation/virtual/kvm/mmu.txt index 3a4d681..daf9c0f 100644 --- a/Documentation/virtual/kvm/mmu.txt +++ b/Documentation/virtual/kvm/mmu.txt @@ -203,10 +203,10 @@ Shadow pages contain the following information: page cannot be destroyed. See role.invalid. parent_ptes: The reverse mapping for the pte/ptes pointing at this page's spt. If - parent_ptes bit 0 is zero, only one spte points at this pages and + parent_ptes bit 0 is zero, only one spte points at this page and parent_ptes points at this single spte, otherwise, there exists multiple sptes pointing at this page and (parent_ptes & ~0x1) points at a data - structure with a list of parent_ptes. + structure with a list of parent sptes. unsync: If true, then the translations in this page may not match the guest's translation. This is equivalent to the state of the tlb when a pte is diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index c5e2363..353d752 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -1099,17 +1099,28 @@ struct rmap_iterator { */ static u64 *rmap_get_first(unsigned long rmap, struct rmap_iterator *iter) { + u64 *sptep; + if (!rmap) return NULL; if (!(rmap & 1)) { iter->desc = NULL; - return (u64 *)rmap; + sptep = (u64 *)rmap; + goto out; } iter->desc = (struct pte_list_desc *)(rmap & ~1ul); iter->pos = 0; - return iter->desc->sptes[iter->pos]; + sptep = iter->desc->sptes[iter->pos]; +out: + /* + * Parent sptes found in sp->parent_ptes lists are also checked here + * since kvm_mmu_unlink_parents() uses this function. If the condition + * needs to be changed for them, make another wrapper function. + */ + WARN_ON(!is_shadow_present_pte(*sptep)); + return sptep; } /* @@ -1119,14 +1130,14 @@ static u64 *rmap_get_first(unsigned long rmap, struct rmap_iterator *iter) */ static u64 *rmap_get_next(struct rmap_iterator *iter) { + u64 *sptep; + if (iter->desc) { if (iter->pos < PTE_LIST_EXT - 1) { - u64 *sptep; - ++iter->pos; sptep = iter->desc->sptes[iter->pos]; if (sptep) - return sptep; + goto out; } iter->desc = iter->desc->more; @@ -1134,17 +1145,20 @@ static u64 *rmap_get_next(struct rmap_iterator *iter) if (iter->desc) { iter->pos = 0; /* desc->sptes[0] cannot be NULL */ - return iter->desc->sptes[iter->pos]; + sptep = iter->desc->sptes[iter->pos]; + goto out; } } return NULL; +out: + WARN_ON(!is_shadow_present_pte(*sptep)); + return sptep; } #define for_each_rmap_spte(_rmap_, _iter_, _spte_) \ for (_spte_ = rmap_get_first(*_rmap_, _iter_); \ - _spte_ && ({BUG_ON(!is_shadow_present_pte(*_spte_)); 1;}); \ - _spte_ = rmap_get_next(_iter_)) + _spte_; _spte_ = rmap_get_next(_iter_)) static void drop_spte(struct kvm *kvm, u64 *sptep) { @@ -1358,7 +1372,6 @@ static bool kvm_zap_rmapp(struct kvm *kvm, unsigned long *rmapp) bool flush = false; while ((sptep = rmap_get_first(*rmapp, &iter))) { - BUG_ON(!(*sptep & PT_PRESENT_MASK)); rmap_printk("%s: spte %p %llx.\n", __func__, sptep, *sptep); drop_spte(kvm, sptep); -- 2.1.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/