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=-1.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,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 75DE0C433DF for ; Tue, 19 May 2020 20:14:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3B66F20873 for ; Tue, 19 May 2020 20:14:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589919268; bh=ZqTQuHxYH0MkHUC6dVn+CA/0CjNcHAiHxB0bgMmBd68=; h=References:In-Reply-To:From:Date:Subject:To:Cc:List-ID:From; b=Zg1pxDGRCKsG+N7mEJaDMSr5i51e6XclWl0Gl9W1nJBUNuO1emT6oO0UrtOFTExJs ezo/EeY5L8LkVWUrj2Ys6/ZdyaYReQjvJG8suKAgzaP11batr00OxL3dd32hnQEK2q TEfCCjFqxFEWHFDuvOPY3xQ4IiD0ewiyxW128RTg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726977AbgESUO1 (ORCPT ); Tue, 19 May 2020 16:14:27 -0400 Received: from mail.kernel.org ([198.145.29.99]:55868 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726447AbgESUO1 (ORCPT ); Tue, 19 May 2020 16:14:27 -0400 Received: from mail-wr1-f50.google.com (mail-wr1-f50.google.com [209.85.221.50]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 4C40D207FB for ; Tue, 19 May 2020 20:14:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589919266; bh=ZqTQuHxYH0MkHUC6dVn+CA/0CjNcHAiHxB0bgMmBd68=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=gxn+9vWGngvikBrEk3ZPZORhFQ3Pv+QDl5P0/jWdVVjyUSDmvsuHsvgxnZMwBURaW N/+6ChpmWebTRn056qY3NJ0/JoxI9URsksny99YMNMosPHSMp+fUKEjbOYWRdCfDZS kT+epaPf3Dz5nmjGjQP+PMDvHiNe4D594DzlDCuE= Received: by mail-wr1-f50.google.com with SMTP id k13so823136wrx.3 for ; Tue, 19 May 2020 13:14:26 -0700 (PDT) X-Gm-Message-State: AOAM531uXPXLIEVv22ijks7qTP/Vu6xDwGauX2JDX7s9Vc2PgCRMXug2 CCOGSTD/7cGpvc94/4yrlTtcq2Q+4e+f/BIhe67Akg== X-Google-Smtp-Source: ABdhPJwKhSdNdUVZLlt9aw0CGJpK84ubff9HxyFuvvlt3AbD8GHEgGuei5C2Yn+pOpTpMdJYT5Xd8qlnBCo0xNl1RSs= X-Received: by 2002:adf:fe45:: with SMTP id m5mr580223wrs.257.1589919264778; Tue, 19 May 2020 13:14:24 -0700 (PDT) MIME-Version: 1.0 References: <20200515234547.710474468@linutronix.de> <20200515235125.921971685@linutronix.de> In-Reply-To: <20200515235125.921971685@linutronix.de> From: Andy Lutomirski Date: Tue, 19 May 2020 13:14:13 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [patch V6 15/37] x86/entry: Change exit path of xen_failsafe_callback To: Thomas Gleixner Cc: LKML , X86 ML , "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)" Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 15, 2020 at 5:10 PM Thomas Gleixner wrote: > > > 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. Seems reasonable: Acked-by: Andy Lutomirski Although a look from a Xen person might be nice too.