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,URIBL_BLOCKED,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 5DFB4C35247 for ; Mon, 3 Feb 2020 15:21:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 31580217BA for ; Mon, 3 Feb 2020 15:21:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728605AbgBCPV2 (ORCPT ); Mon, 3 Feb 2020 10:21:28 -0500 Received: from mga02.intel.com ([134.134.136.20]:32939 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728548AbgBCPVY (ORCPT ); Mon, 3 Feb 2020 10:21:24 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by orsmga101.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 03 Feb 2020 07:21:23 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,398,1574150400"; d="scan'208";a="429473368" Received: from lxy-dell.sh.intel.com ([10.239.13.109]) by fmsmga005.fm.intel.com with ESMTP; 03 Feb 2020 07:21:21 -0800 From: Xiaoyao Li To: Paolo Bonzini , Sean Christopherson , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Andy Lutomirski Cc: x86@kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, David Laight , Xiaoyao Li Subject: [PATCH v2 3/6] kvm: x86: Emulate split-lock access as a write Date: Mon, 3 Feb 2020 23:16:05 +0800 Message-Id: <20200203151608.28053-4-xiaoyao.li@intel.com> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20200203151608.28053-1-xiaoyao.li@intel.com> References: <20200203151608.28053-1-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 to avoid malicous guest polluting the kernel log. More detail analysis can be found: https://lkml.kernel.org/r/20200131200134.GD18946@linux.intel.com Signed-off-by: Xiaoyao Li --- arch/x86/kvm/x86.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 2d3be7f3ad67..821b7404c0fd 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -5847,6 +5847,13 @@ static int emulator_write_emulated(struct x86_emulate_ctxt *ctxt, (cmpxchg64((u64 *)(ptr), *(u64 *)(old), *(u64 *)(new)) == *(u64 *)(old)) #endif +static inline bool across_cache_line_access(gpa_t gpa, unsigned int bytes) +{ + unsigned int cache_line_size = cache_line_size(); + + return (gpa & (cache_line_size - 1)) + bytes > cache_line_size; +} + static int emulator_cmpxchg_emulated(struct x86_emulate_ctxt *ctxt, unsigned long addr, const void *old, @@ -5873,6 +5880,10 @@ static int emulator_cmpxchg_emulated(struct x86_emulate_ctxt *ctxt, if (((gpa + bytes - 1) & PAGE_MASK) != (gpa & PAGE_MASK)) goto emul_write; + if (get_split_lock_detect_state() != sld_off && + across_cache_line_access(gpa, bytes)) + goto emul_write; + if (kvm_vcpu_map(vcpu, gpa_to_gfn(gpa), &map)) goto emul_write; -- 2.23.0