From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, HK_RANDOM_FROM,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 359ECC352A2 for ; Thu, 6 Feb 2020 07:09:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 09BFD214AF for ; Thu, 6 Feb 2020 07:09:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728033AbgBFHJk (ORCPT ); Thu, 6 Feb 2020 02:09:40 -0500 Received: from mga04.intel.com ([192.55.52.120]:56103 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727904AbgBFHJe (ORCPT ); Thu, 6 Feb 2020 02:09:34 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga003.jf.intel.com ([10.7.209.27]) by fmsmga104.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 05 Feb 2020 23:09:34 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,408,1574150400"; d="scan'208";a="231957251" Received: from lxy-dell.sh.intel.com ([10.239.13.109]) by orsmga003.jf.intel.com with ESMTP; 05 Feb 2020 23:09:31 -0800 From: Xiaoyao Li To: Thomas Gleixner , Ingo Molnar , Borislav Petkov , hpa@zytor.com, Paolo Bonzini , Sean Christopherson , Andy Lutomirski , tony.luck@intel.com Cc: peterz@infradead.org, fenghua.yu@intel.com, x86@kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Xiaoyao Li Subject: [PATCH v3 5/8] kvm: x86: Emulate split-lock access as a write Date: Thu, 6 Feb 2020 15:04:09 +0800 Message-Id: <20200206070412.17400-6-xiaoyao.li@intel.com> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20200206070412.17400-1-xiaoyao.li@intel.com> References: <20200206070412.17400-1-xiaoyao.li@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If split lock detect is enabled (warn/fatal), #AC handler calls die() when split lock happens in kernel. A sane guest should never tigger emulation on a split-lock access, but it cannot prevent malicous guest from doing this. So just emulating the access as a write if it's a split-lock access (the same as access spans page) to avoid malicous guest polluting the kernel log. More detail analysis can be found: https://lkml.kernel.org/r/20200131200134.GD18946@linux.intel.com Suggested-by: Sean Christopherson Signed-off-by: Xiaoyao Li --- v3: - intergrate cache split case into page split case to reuse the logic; --- arch/x86/kvm/x86.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 2d3be7f3ad67..fab4d25575bf 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -5856,6 +5856,7 @@ static int emulator_cmpxchg_emulated(struct x86_emulate_ctxt *ctxt, { struct kvm_host_map map; struct kvm_vcpu *vcpu = emul_to_vcpu(ctxt); + u64 page_line_mask = PAGE_MASK; gpa_t gpa; char *kaddr; bool exchanged; @@ -5870,7 +5871,11 @@ static int emulator_cmpxchg_emulated(struct x86_emulate_ctxt *ctxt, (gpa & PAGE_MASK) == APIC_DEFAULT_PHYS_BASE) goto emul_write; - if (((gpa + bytes - 1) & PAGE_MASK) != (gpa & PAGE_MASK)) + if (split_lock_detect_enabled()) + page_line_mask = ~(cache_line_size() - 1); + + /* when write spans page or spans cache when SLD enabled */ + if (((gpa + bytes - 1) & page_line_mask) != (gpa & page_line_mask)) goto emul_write; if (kvm_vcpu_map(vcpu, gpa_to_gfn(gpa), &map)) -- 2.23.0