From patchwork Tue Feb 5 21:01:32 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sean Christopherson X-Patchwork-Id: 10798467 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 1D375922 for ; Tue, 5 Feb 2019 21:03:01 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 091252C9D9 for ; Tue, 5 Feb 2019 21:03:01 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 0722B2CA0E; Tue, 5 Feb 2019 21:03:00 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 8FBB72C978 for ; Tue, 5 Feb 2019 21:03:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730169AbfBEVC7 (ORCPT ); Tue, 5 Feb 2019 16:02:59 -0500 Received: from mga07.intel.com ([134.134.136.100]:30441 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730127AbfBEVC6 (ORCPT ); Tue, 5 Feb 2019 16:02:58 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by orsmga105.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 05 Feb 2019 13:02:58 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.58,336,1544515200"; d="scan'208";a="131343552" Received: from sjchrist-coffee.jf.intel.com ([10.54.74.14]) by FMSMGA003.fm.intel.com with ESMTP; 05 Feb 2019 13:02:58 -0800 From: Sean Christopherson To: Paolo Bonzini , =?utf-8?b?UmFkaW0gS3LEjW3DocWZ?= Cc: kvm@vger.kernel.org, Xiao Guangrong Subject: [PATCH v2 22/27] KVM: x86/mmu: skip over invalid root pages when zapping all sptes Date: Tue, 5 Feb 2019 13:01:32 -0800 Message-Id: <20190205210137.1377-22-sean.j.christopherson@intel.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190205205443.1059-1-sean.j.christopherson@intel.com> References: <20190205205443.1059-1-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 X-Virus-Scanned: ClamAV using ClamSMTP ...to guarantee forward progress. When zapped, root pages are marked invalid and moved to the head of the active pages list until they are explicitly freed. Theoretically, having unzappable root pages at the head of the list could prevent kvm_mmu_zap_all() from making forward progress were a future patch to add a loop restart after processing a page, e.g. to drop mmu_lock on contention. Although kvm_mmu_prepare_zap_page() can theoretically take action on invalid pages, e.g. to zap unsync children, functionally it's not necessary (root pages will be re-zapped when freed) and practically speaking the odds of e.g. @unsync or @unsync_children becoming %true while zapping all pages is basically nil. Signed-off-by: Sean Christopherson --- arch/x86/kvm/mmu.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index bdba6c85f81f..3ceabf3e7e0d 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -5850,9 +5850,12 @@ 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) + list_for_each_entry_safe(sp, node, &kvm->arch.active_mmu_pages, link) { + if (sp->role.invalid && sp->root_count) + continue; if (kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list)) goto restart; + } kvm_mmu_commit_zap_page(kvm, &invalid_list); spin_unlock(&kvm->mmu_lock);