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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 E27B1C76195 for ; Thu, 18 Jul 2019 14:13:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C2C9921783 for ; Thu, 18 Jul 2019 14:13:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390502AbfGRONn (ORCPT ); Thu, 18 Jul 2019 10:13:43 -0400 Received: from mail-wr1-f67.google.com ([209.85.221.67]:43697 "EHLO mail-wr1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727730AbfGRONn (ORCPT ); Thu, 18 Jul 2019 10:13:43 -0400 Received: by mail-wr1-f67.google.com with SMTP id p13so28852824wru.10 for ; Thu, 18 Jul 2019 07:13:42 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:openpgp:message-id :date:user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=aitVK5dUi4iEyTg8KMkolW2+9CkRNR/J+VhQtXZUx7o=; b=g9OXbF7btNF2T67o8fT8dYpFsosZj2fd1uvfUCAcYDUsyd085lGJFy5PPwAciu9+Kv VVRlou21R0WldMrP3vkNpExnjrL/K2cuUxBNTrf1Yx2Ff2Bu1DKrUoFwMV6opAf+v++V 55rp+0tMgWepTxYMc+JYbWg0mFFLEFjhCZ0wR/nF7tI30+1HOECOhCN91870bPqV9HT4 +hbHx1rz5k2rDRHKKb578/sMQlDxyPgWrZpdsGH963LNUOdr4uQx+yd+iO3E/15Q13KK DJ47p5WE4gZsCeIQ8K3DbXdaWYBx3o7IaJKvNTCXmwwi8VJNWaYuai1F22VOUDoweqUo C2bA== X-Gm-Message-State: APjAAAV7eRD2740oXACELTeIY9W4H2DDBFX1pv/jvfq0SxziIgCFSVgY M9s7OWqdyzIbDBHo7StszQbUuIu6M+uL4g== X-Google-Smtp-Source: APXvYqy4uIh+8Y3VPnsbRO6NYSm6LtRCImetvfh+P5rVBBkEbFi9FhuTmF4xj0Et+xPHBUNXbpOX4w== X-Received: by 2002:adf:fe09:: with SMTP id n9mr52667728wrr.41.1563459221549; Thu, 18 Jul 2019 07:13:41 -0700 (PDT) Received: from ?IPv6:2001:b07:6468:f312:e427:3beb:1110:dda2? ([2001:b07:6468:f312:e427:3beb:1110:dda2]) by smtp.gmail.com with ESMTPSA id z1sm30251747wrp.51.2019.07.18.07.13.40 (version=TLS1_3 cipher=AEAD-AES128-GCM-SHA256 bits=128/128); Thu, 18 Jul 2019 07:13:40 -0700 (PDT) Subject: Re: [PATCH v2 04/22] x86/kvm: Don't call kvm_spurious_fault() from .fixup To: Josh Poimboeuf Cc: Sean Christopherson , x86@kernel.org, linux-kernel@vger.kernel.org, Peter Zijlstra , Thomas Gleixner , Nick Desaulniers , Arnd Bergmann , Jann Horn , Randy Dunlap , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= References: <64a9b64d127e87b6920a97afde8e96ea76f6524e.1563413318.git.jpoimboe@redhat.com> <65bbf58d-f88b-c7d6-523b-6e35f4972bf2@redhat.com> <20190718131654.GE28096@linux.intel.com> <1b891612-18e6-48ed-cfb5-05e8aca79dcb@redhat.com> <20190718141210.us7giumvgbgifvtv@treble> From: Paolo Bonzini Openpgp: preference=signencrypt Message-ID: <86ce6b06-baa7-51a2-b3ea-142547b7f3c3@redhat.com> Date: Thu, 18 Jul 2019 16:13:39 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: <20190718141210.us7giumvgbgifvtv@treble> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 18/07/19 16:12, Josh Poimboeuf wrote: > On Thu, Jul 18, 2019 at 03:18:50PM +0200, Paolo Bonzini wrote: >> On 18/07/19 15:16, Sean Christopherson wrote: >>>> Acked-by: Paolo Bonzini >>>> >>>> This has a side effect of adding a jump in a generally hot path, but >>>> let's hope that the speculation gods for once help us. >>> Any reason not to take the same approach as vmx_vmenter() and ud2 directly >>> from fixup? I've never found kvm_spurious_fault() to be all that helpful, >>> IMO it's a win win. :-) >> >> Honestly I've never seen a backtrace from here but I would rather not >> regret this when a customer encounters it... > > In theory, changing the "call kvm_spurious_fault" to ud2 should be fine. > It should be tested, of course. > > I would defer to Sean to make the patch on top of mine :-) > Yes, this can be done easily on top. Paolo