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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, 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 EFF76C43331 for ; Thu, 2 Apr 2020 15:56:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D10F020757 for ; Thu, 2 Apr 2020 15:56:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389680AbgDBP4x (ORCPT ); Thu, 2 Apr 2020 11:56:53 -0400 Received: from mga06.intel.com ([134.134.136.31]:50594 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389627AbgDBP4v (ORCPT ); Thu, 2 Apr 2020 11:56:51 -0400 IronPort-SDR: ICu/c4KiZyA407sSE+7/DVI1S51FIZMOSxE0DBewjRjqjh9ukxqfN3CLbWBIN82khm4sWawLJh jdzIVkv9Hsdg== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Apr 2020 08:56:49 -0700 IronPort-SDR: WOh0tZZUR7nYfDfkljwsZyG5Hh+gNA+F9Ymy3BoEYIocTeJHaCyMsmtClKuCz+/Rw8jPxCZUGk NsKAxf6sKOEA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.72,336,1580803200"; d="scan'208";a="396413087" Received: from sjchrist-coffee.jf.intel.com ([10.54.74.202]) by orsmga004.jf.intel.com with ESMTP; 02 Apr 2020 08:56:49 -0700 From: Sean Christopherson To: Thomas Gleixner Cc: x86@kernel.org, "Kenneth R . Crudup" , Paolo Bonzini , Fenghua Yu , Xiaoyao Li , Nadav Amit , Thomas Hellstrom , Sean Christopherson , Tony Luck , Peter Zijlstra , Jessica Yu , Steven Rostedt , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 3/3] KVM: VMX: Extend VMX's #AC interceptor to handle split lock #AC in guest Date: Thu, 2 Apr 2020 08:55:54 -0700 Message-Id: <20200402155554.27705-4-sean.j.christopherson@intel.com> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200402155554.27705-1-sean.j.christopherson@intel.com> References: <20200402124205.334622628@linutronix.de> <20200402155554.27705-1-sean.j.christopherson@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 From: Xiaoyao Li Two types #AC can be generated in Intel CPUs: 1. legacy alignment check #AC 2. split lock #AC Reflect #AC back into the guest if the guest has legacy alignment checks enabled or if SLD is disabled. If SLD is enabled, treat the guest like a host userspace application by calling handle_user_split_lock(). If the #AC is handled (SLD disabled and TIF_SLD set), then simply resume the guest. If the #AC isn't handled, i.e. host is sld_fatal, then forward the #AC to the userspace VMM, similar to sending SIGBUS. Suggested-by: Sean Christopherson Signed-off-by: Xiaoyao Li Signed-off-by: Sean Christopherson --- arch/x86/kvm/vmx/vmx.c | 30 +++++++++++++++++++++++++++--- 1 file changed, 27 insertions(+), 3 deletions(-) diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 458e684dfbdc..a96cfda0a5b9 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -4623,6 +4623,12 @@ 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); @@ -4688,9 +4694,6 @@ 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 & @@ -4719,6 +4722,27 @@ 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: + /* + * Reflect #AC to the guest if it's expecting the #AC, i.e. has + * legacy alignment check enabled. Pre-check host split lock + * turned on to avoid the VMREADs needed to check legacy #AC, + * i.e. reflect the #AC if the only possible source is legacy + * alignment checks. + */ + if (!boot_cpu_has(X86_FEATURE_SPLIT_LOCK_DETECT) || + guest_cpu_alignment_check_enabled(vcpu)) { + kvm_queue_exception_e(vcpu, AC_VECTOR, error_code); + return 1; + } + + /* + * Forward the #AC to userspace if kernel policy does not allow + * temporarily disabling split lock detection. + */ + if (handle_user_split_lock(kvm_rip_read(vcpu))) + return 1; + fallthrough; default: kvm_run->exit_reason = KVM_EXIT_EXCEPTION; kvm_run->ex.exception = ex_no; -- 2.24.1