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=-11.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,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 E9927C433DB for ; Tue, 2 Feb 2021 09:02:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AD12A64F5D for ; Tue, 2 Feb 2021 09:02:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232812AbhBBJCO (ORCPT ); Tue, 2 Feb 2021 04:02:14 -0500 Received: from mga02.intel.com ([134.134.136.20]:41952 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231860AbhBBJCG (ORCPT ); Tue, 2 Feb 2021 04:02:06 -0500 IronPort-SDR: XrMKU2HkKx9fiW3b+H1yepyU/f6S4zqM/oXovb0QfotGbQqPIk0nKyEpINDWtcnov1J7rPAf5C YgLi144x3qzw== X-IronPort-AV: E=McAfee;i="6000,8403,9882"; a="167929199" X-IronPort-AV: E=Sophos;i="5.79,394,1602572400"; d="scan'208";a="167929199" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Feb 2021 01:01:22 -0800 IronPort-SDR: j3yg88fjdQC+eiSMyKy4p3zWzkI+sP40x0+NIYX0vo96ZYxg1B70EnzDxjKhf5KBBRDVDwY8lL k4TMvYAqMf3A== X-IronPort-AV: E=Sophos;i="5.79,394,1602572400"; d="scan'208";a="479491878" Received: from chenyi-pc.sh.intel.com ([10.239.159.24]) by fmsmga001-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Feb 2021 01:01:20 -0800 From: Chenyi Qiang To: Paolo Bonzini , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Xiaoyao Li Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 0/3] Add KVM support for bus lock debug exception Date: Tue, 2 Feb 2021 17:04:30 +0800 Message-Id: <20210202090433.13441-1-chenyi.qiang@intel.com> X-Mailer: git-send-email 2.17.1 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org A bus lock is acquired either through split locked access to writeback (WB) memory or by using locks to uncacheable (UC) memory. This is typically > 1000 cycles slower than atomic opertaion within a cache line. It also disrupts performance on other cores. Bus lock debug exception is a sub-feature of bus lock detection. It is an ability to notify the kernel by an #DB trap after the instruction acquires a bus lock when CPL>0. This allows the kernel to enforce user application throttling or mitigatioins. Expose the bus lock debug exception to guest by the enumeration of CPUID.(EAX=7,ECX=0).ECX[24]. Software in guest can enable these exceptions by setting the DEBUGCTLMSR_BUS_LOCK_DETECT(bit 2) of MSR_IA32_DEBUTCTL. The bus lock #DB exception can also be intercepted by the VMM and identified through the bit 11 of the exit qualification at VM exit. The bit 11 (DR6_BUS_LOCK) of DR6 register is introduced to indicate a bus lock #DB exception. DR6_BUS_LOCK has formerly always been 1 and delivery of a bus lock #DB clears it. The VMM should emulate the exceptions by clearing the bit 11 of the guest DR6. Bus lock debug exception kernel patches are available at: https://lore.kernel.org/lkml/20201124205245.4164633-1-fenghua.yu@intel.com Document for Bus Lock Detection is now available at the latest "Intel Architecture Instruction Set Extensions Programming Reference". Document Link: https://software.intel.com/content/www/us/en/develop/download/intel-architecture-instruction-set-extensions-programming-reference.html --- Changelogs v1->v2: - rename the DR6_INIT to DR6_LOW_ACTIVE suggested by Paolo and split it out as a new commit. - KVM v1:https://lore.kernel.org/lkml/20210108064924.1677-1-chenyi.qiang@intel.com Chenyi Qiang (3): KVM: X86: Rename DR6_INIT to DR6_ACTIVE_LOW KVM: X86: Add support for the emulation of DR6_BUS_LOCK bit KVM: X86: Expose bus lock debug exception to guest arch/x86/include/asm/kvm_host.h | 14 +++++++-- arch/x86/kvm/cpuid.c | 3 +- arch/x86/kvm/emulate.c | 2 +- arch/x86/kvm/svm/nested.c | 2 +- arch/x86/kvm/svm/svm.c | 6 ++-- arch/x86/kvm/vmx/nested.c | 4 +-- arch/x86/kvm/vmx/vmx.c | 27 ++++++++++++++--- arch/x86/kvm/x86.c | 52 +++++++++++++++------------------ arch/x86/kvm/x86.h | 2 ++ 9 files changed, 69 insertions(+), 43 deletions(-) -- 2.17.1