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=unavailable 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 DB2ACC2D0B1 for ; Thu, 6 Feb 2020 07:09:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B339420838 for ; Thu, 6 Feb 2020 07:09:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728069AbgBFHJn (ORCPT ); Thu, 6 Feb 2020 02:09:43 -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 S1728009AbgBFHJh (ORCPT ); Thu, 6 Feb 2020 02:09:37 -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 23:09:37 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,408,1574150400"; d="scan'208";a="231957263" Received: from lxy-dell.sh.intel.com ([10.239.13.109]) by orsmga003.jf.intel.com with ESMTP; 05 Feb 2020 23:09:34 -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 6/8] kvm: vmx: Extend VMX's #AC interceptor to handle split lock #AC happens in guest Date: Thu, 6 Feb 2020 15:04:10 +0800 Message-Id: <20200206070412.17400-7-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 There are two types of #AC can be generated in Intel CPUs: 1. legacy alignment check #AC; 2. split lock #AC; Legacy alignment check #AC can be injected to guest if guest has enabled alignemnet check. when host enables split lock detectin, i.e., split_lock_detect != off, there will be an unexpected #AC in guest and intercepted by KVM because KVM doesn't virtualize this feature to guest and hardware value of MSR_TEST_CTRL.SLD bit stays unchanged when vcpu is running. To handle this unexpected #AC, treat guest just like host usermode that calling handle_user_split_lock(): - If host is sld_warn, it warns and set TIF_SLD so that __switch_to_xtra() does the MSR_TEST_CTRL.SLD bit switching when control transfer to/from this vcpu. - If host is sld_fatal, forward #AC to userspace, the similar as sending SIGBUS. Suggested-by: Sean Christopherson Signed-off-by: Xiaoyao Li --- v3: - Use handle_user_split_lock() to handle unexpected #AC in guest. --- arch/x86/kvm/vmx/vmx.c | 31 ++++++++++++++++++++++++++++--- 1 file changed, 28 insertions(+), 3 deletions(-) diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index c475fa2aaae0..822211975e6c 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -4557,6 +4557,12 @@ static int handle_machine_check(struct kvm_vcpu *vcpu) return 1; } +static inline bool guest_cpu_alignment_check_enabled(struct kvm_vcpu *vcpu) +{ + return vmx_get_cpl(vcpu) == 3 && kvm_read_cr0_bits(vcpu, X86_CR0_AM) && + (kvm_get_rflags(vcpu) & X86_EFLAGS_AC); +} + static int handle_exception_nmi(struct kvm_vcpu *vcpu) { struct vcpu_vmx *vmx = to_vmx(vcpu); @@ -4622,9 +4628,6 @@ static int handle_exception_nmi(struct kvm_vcpu *vcpu) return handle_rmode_exception(vcpu, ex_no, error_code); switch (ex_no) { - case AC_VECTOR: - kvm_queue_exception_e(vcpu, AC_VECTOR, error_code); - return 1; case DB_VECTOR: dr6 = vmcs_readl(EXIT_QUALIFICATION); if (!(vcpu->guest_debug & @@ -4653,6 +4656,28 @@ static int handle_exception_nmi(struct kvm_vcpu *vcpu) kvm_run->debug.arch.pc = vmcs_readl(GUEST_CS_BASE) + rip; kvm_run->debug.arch.exception = ex_no; break; + case AC_VECTOR: + /* + * Inject #AC back to guest only when guest enables legacy + * alignment check. + * Otherwise, it must be an unexpected split lock #AC of guest + * since hardware SPLIT_LOCK_DETECT bit keeps unchanged set + * when vcpu is running. In this case, treat guest the same as + * user space application that calls handle_user_split_lock(): + * - If sld_state = sld_warn, it sets TIF_SLD and disables SLD + * for this vcpu thread. + * - If sld_state = sld_fatal, we forward #AC to userspace, + * similar as sending SIGBUS. + */ + if (!split_lock_detect_enabled() || + guest_cpu_alignment_check_enabled(vcpu)) { + kvm_queue_exception_e(vcpu, AC_VECTOR, error_code); + return 1; + } + + if (handle_user_split_lock(kvm_rip_read(vcpu))) + return 1; + /* fall through */ default: kvm_run->exit_reason = KVM_EXIT_EXCEPTION; kvm_run->ex.exception = ex_no; -- 2.23.0