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=-3.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 28C41C2BA2B for ; Fri, 10 Apr 2020 11:56:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 07A9A2084D for ; Fri, 10 Apr 2020 11:56:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726690AbgDJL4I (ORCPT ); Fri, 10 Apr 2020 07:56:08 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:54440 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725913AbgDJL4I (ORCPT ); Fri, 10 Apr 2020 07:56:08 -0400 Received: from p5de0bf0b.dip0.t-ipconnect.de ([93.224.191.11] helo=nanos.tec.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1jMsGP-0004bl-BG; Fri, 10 Apr 2020 13:56:01 +0200 Received: from nanos.tec.linutronix.de (localhost [IPv6:::1]) by nanos.tec.linutronix.de (Postfix) with ESMTP id ADEF2100BB6; Fri, 10 Apr 2020 13:56:00 +0200 (CEST) Message-Id: <20200410115516.978037132@linutronix.de> User-Agent: quilt/0.65 Date: Fri, 10 Apr 2020 13:54:00 +0200 From: Thomas Gleixner To: LKML Cc: x86@kernel.org, "Kenneth R. Crudup" , Paolo Bonzini , Fenghua Yu , Xiaoyao Li , Nadav Amit , Thomas Hellstrom , Sean Christopherson , Tony Luck Subject: [patch 1/3] x86/split_lock: Provide handle_guest_split_lock() References: <20200410115359.242241855@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-transfer-encoding: 8-bit X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Thomas Gleixner Without at least minimal handling for split lock detection induced #AC, VMX will just run into the same problem as the VMWare hypervisor, which was reported by Kenneth. It will inject the #AC blindly into the guest whether the guest is prepared or not. Provide a function for guest mode which acts depending on the host SLD mode. If mode == sld_warn, treat it like user space, i.e. emit a warning disable SLD and mark the task accordingly. Otherwise force SIGBUS. Signed-off-by: Thomas Gleixner Cc: "Kenneth R. Crudup" Cc: Paolo Bonzini Cc: Fenghua Yu Cc: Xiaoyao Li Cc: Nadav Amit Cc: Thomas Hellstrom Cc: Sean Christopherson Cc: Tony Luck --- arch/x86/include/asm/cpu.h | 1 + arch/x86/kernel/cpu/intel.c | 33 ++++++++++++++++++++++++++++----- 2 files changed, 29 insertions(+), 5 deletions(-) --- a/arch/x86/include/asm/cpu.h +++ b/arch/x86/include/asm/cpu.h @@ -44,6 +44,7 @@ unsigned int x86_stepping(unsigned int s extern void __init cpu_set_core_cap_bits(struct cpuinfo_x86 *c); extern void switch_to_sld(unsigned long tifn); extern bool handle_user_split_lock(struct pt_regs *regs, long error_code); +extern bool handle_guest_split_lock(unsigned long ip); #else static inline void __init cpu_set_core_cap_bits(struct cpuinfo_x86 *c) {} static inline void switch_to_sld(unsigned long tifn) {} --- a/arch/x86/kernel/cpu/intel.c +++ b/arch/x86/kernel/cpu/intel.c @@ -21,6 +21,7 @@ #include #include #include +#include #ifdef CONFIG_X86_64 #include @@ -1066,13 +1067,10 @@ static void split_lock_init(void) split_lock_verify_msr(sld_state != sld_off); } -bool handle_user_split_lock(struct pt_regs *regs, long error_code) +static void split_lock_warn(unsigned long ip) { - if ((regs->flags & X86_EFLAGS_AC) || sld_state == sld_fatal) - return false; - pr_warn_ratelimited("#AC: %s/%d took a split_lock trap at address: 0x%lx\n", - current->comm, current->pid, regs->ip); + current->comm, current->pid, ip); /* * Disable the split lock detection for this task so it can make @@ -1081,6 +1079,31 @@ bool handle_user_split_lock(struct pt_re */ sld_update_msr(false); set_tsk_thread_flag(current, TIF_SLD); +} + +bool handle_guest_split_lock(unsigned long ip) +{ + if (sld_state == sld_warn) { + split_lock_warn(ip); + return true; + } + + pr_warn_once("#AC: %s/%d %s split_lock trap at address: 0x%lx\n", + current->comm, current->pid, + sld_state == sld_fatal ? "fatal" : "bogus", ip); + + current->thread.error_code = 0; + current->thread.trap_nr = X86_TRAP_AC; + force_sig_fault(SIGBUS, BUS_ADRALN, NULL); + return false; +} +EXPORT_SYMBOL_GPL(handle_guest_split_lock); + +bool handle_user_split_lock(struct pt_regs *regs, long error_code) +{ + if ((regs->flags & X86_EFLAGS_AC) || sld_state == sld_fatal) + return false; + split_lock_warn(regs->ip); return true; }