From patchwork Fri Nov 3 05:53:27 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Haozhong Zhang X-Patchwork-Id: 10039567 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id E7D15602DA for ; Fri, 3 Nov 2017 05:54:22 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D88982934D for ; Fri, 3 Nov 2017 05:54:22 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id CD2A1294B6; Fri, 3 Nov 2017 05:54:22 +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=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable 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 76C5A2934D for ; Fri, 3 Nov 2017 05:54:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753054AbdKCFyJ (ORCPT ); Fri, 3 Nov 2017 01:54:09 -0400 Received: from mga07.intel.com ([134.134.136.100]:45300 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752435AbdKCFyG (ORCPT ); Fri, 3 Nov 2017 01:54:06 -0400 Received: from orsmga005.jf.intel.com ([10.7.209.41]) by orsmga105.jf.intel.com with ESMTP; 02 Nov 2017 22:54:05 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.44,337,1505804400"; d="scan'208";a="168772112" Received: from hz-desktop.sh.intel.com (HELO localhost) ([10.239.159.142]) by orsmga005.jf.intel.com with ESMTP; 02 Nov 2017 22:54:03 -0700 From: Haozhong Zhang To: kvm@vger.kernel.org, x86@kernel.org Cc: linux-kernel@vger.kernel.org, Paolo Bonzini , rkrcmar@redhat.com, Xiao Guangrong , Dan Williams , ivan.d.cuevas.escareno@intel.com, karthik.kumar@intel.com, Konrad Rzeszutek Wilk , Olif Chapman , Haozhong Zhang , Ingo Molnar Subject: [PATCH v4 3/3] KVM: MMU: consider host cache mode in MMIO page check Date: Fri, 3 Nov 2017 13:53:27 +0800 Message-Id: <20171103055327.21684-4-haozhong.zhang@intel.com> X-Mailer: git-send-email 2.14.1 In-Reply-To: <20171103055327.21684-1-haozhong.zhang@intel.com> References: <20171103055327.21684-1-haozhong.zhang@intel.com> Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Some reserved pages, such as those from NVDIMM DAX devices, are not for MMIO, and can be mapped with cached memory type for better performance. However, the above check misconceives those pages as MMIO. Because KVM maps MMIO pages with UC memory type, the performance of guest accesses to those pages would be harmed. Therefore, we check the host memory type by lookup_memtype() in addition and only treat UC/UC- pages as MMIO. Signed-off-by: Haozhong Zhang Reported-by: Cuevas Escareno, Ivan D Reported-by: Kumar, Karthik --- arch/x86/kvm/mmu.c | 19 ++++++++++++++++++- 1 file changed, 18 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 0b481cc9c725..e9ed0e666a83 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -2708,7 +2708,24 @@ static bool mmu_need_write_protect(struct kvm_vcpu *vcpu, gfn_t gfn, static bool kvm_is_mmio_pfn(kvm_pfn_t pfn) { if (pfn_valid(pfn)) - return !is_zero_pfn(pfn) && PageReserved(pfn_to_page(pfn)); + return !is_zero_pfn(pfn) && PageReserved(pfn_to_page(pfn)) && + /* + * Some reserved pages, such as those from + * NVDIMM DAX devices, are not for MMIO, and + * can be mapped with cached memory type for + * better performance. However, the above + * check misconceives those pages as MMIO. + * Because KVM maps MMIO pages with UC memory + * type, the performance of guest accesses to + * those pages would be harmed. Therefore, we + * check the host memory type in addition and + * only treat UC/UC- pages as MMIO. + * + * pat_pfn_is_uc() works only when PAT is enabled, + * so check pat_enabled() as well. + */ + (!pat_enabled() || + pat_pfn_is_uc(kvm_pfn_t_to_pfn_t(pfn))); return true; }