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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 595ACC433DF for ; Sat, 16 May 2020 00:12:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3D52C2078B for ; Sat, 16 May 2020 00:12:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728384AbgEPAMW (ORCPT ); Fri, 15 May 2020 20:12:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41104 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1727973AbgEPAKz (ORCPT ); Fri, 15 May 2020 20:10:55 -0400 Received: from Galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 270FEC05BD09 for ; Fri, 15 May 2020 17:10:55 -0700 (PDT) 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 1jZkPJ-0002GW-VV; Sat, 16 May 2020 02:10:26 +0200 Received: from nanos.tec.linutronix.de (localhost [IPv6:::1]) by nanos.tec.linutronix.de (Postfix) with ESMTP id 73123FF834; Sat, 16 May 2020 02:10:25 +0200 (CEST) Message-Id: <20200515235125.921971685@linutronix.de> User-Agent: quilt/0.65 Date: Sat, 16 May 2020 01:46:02 +0200 From: Thomas Gleixner To: LKML Cc: x86@kernel.org, "Paul E. McKenney" , Andy Lutomirski , Alexandre Chartre , Frederic Weisbecker , Paolo Bonzini , Sean Christopherson , Masami Hiramatsu , Petr Mladek , Steven Rostedt , Joel Fernandes , Boris Ostrovsky , Juergen Gross , Brian Gerst , Mathieu Desnoyers , Josh Poimboeuf , Will Deacon , Tom Lendacky , Wei Liu , Michael Kelley , Jason Chen CJ , Zhao Yakui , "Peter Zijlstra (Intel)" Subject: [patch V6 15/37] x86/entry: Change exit path of xen_failsafe_callback References: <20200515234547.710474468@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 xen_failsafe_callback is invoked from XEN for two cases: 1. Fault while reloading DS, ES, FS or GS 2. Fault while executing IRET #1 retries the IRET after XEN has fixed up the segments. #2 injects a #GP which kills the task For #1 there is no reason to go through the full exception return path because the tasks TIF state is still the same. So just going straight to the IRET path is good enough. Signed-off-by: Thomas Gleixner Cc: Boris Ostrovsky Cc: Juergen Gross diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S index dd8064ffdf12..65fd41fe77d9 100644 --- a/arch/x86/entry/entry_32.S +++ b/arch/x86/entry/entry_32.S @@ -1352,7 +1352,7 @@ SYM_FUNC_START(xen_failsafe_callback) 5: pushl $-1 /* orig_ax = -1 => not a system call */ SAVE_ALL ENCODE_FRAME_POINTER - jmp ret_from_exception + jmp handle_exception_return .section .fixup, "ax" 6: xorl %eax, %eax diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index 1157d63b3682..55f612032793 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -1175,7 +1175,7 @@ SYM_CODE_START(xen_failsafe_callback) pushq $-1 /* orig_ax = -1 => not a system call */ PUSH_AND_CLEAR_REGS ENCODE_FRAME_POINTER - jmp error_exit + jmp error_return SYM_CODE_END(xen_failsafe_callback) #endif /* CONFIG_XEN_PV */