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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 71FE2C3A5A2 for ; Fri, 23 Aug 2019 21:55:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 46B66206E0 for ; Fri, 23 Aug 2019 21:55:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2393346AbfHWVzW (ORCPT ); Fri, 23 Aug 2019 17:55:22 -0400 Received: from mga12.intel.com ([192.55.52.136]:43389 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388000AbfHWVzW (ORCPT ); Fri, 23 Aug 2019 17:55:22 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga106.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 23 Aug 2019 14:55:21 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,422,1559545200"; d="scan'208";a="263305949" Received: from sjchrist-coffee.jf.intel.com (HELO linux.intel.com) ([10.54.74.41]) by orsmga001.jf.intel.com with ESMTP; 23 Aug 2019 14:55:21 -0700 Date: Fri, 23 Aug 2019 14:55:21 -0700 From: Sean Christopherson To: Liran Alon Cc: Paolo Bonzini , Radim =?utf-8?B?S3LEjW3DocWZ?= , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RESEND PATCH 04/13] KVM: x86: Drop EMULTYPE_NO_UD_ON_FAIL as a standalone type Message-ID: <20190823215521.GD24772@linux.intel.com> References: <20190823010709.24879-1-sean.j.christopherson@intel.com> <20190823010709.24879-5-sean.j.christopherson@intel.com> <4993FDBF-6641-43E9-BCEE-7F5FE58561E9@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 23, 2019 at 04:32:05PM +0300, Liran Alon wrote: > > > On 23 Aug 2019, at 16:21, Liran Alon wrote: > > > >> On 23 Aug 2019, at 4:07, Sean Christopherson wrote: > >> > >> The "no #UD on fail" is used only in the VMWare case, and for the VMWare > >> scenario it really means "#GP instead of #UD on fail". Remove the flag > >> in preparation for moving all fault injection into the emulation flow > >> itself, which in turn will allow eliminating EMULATE_DONE and company. > >> > >> Signed-off-by: Sean Christopherson > > > > When I created the commit which introduced this e23661712005 ("KVM: x86: > > Add emulation_type to not raise #UD on emulation failure") I intentionally > > introduced a new flag to emulation_type instead of using EMULTYPE_VMWARE as > > I thought it’s weird to couple this behaviour specifically with VMware > > emulation. As it made sense to me that there could be more scenarios in > > which some VMExit handler would like to use the x86 emulator but in case of > > failure want to decide what would be the failure handling from the outside. > > I also didn’t want the x86 emulator to be aware of VMware interception > > internals. > > > > Having said that, one could argue that the x86 emulator already knows about > > the VMware interception internals because of how x86_emulate_instruction() > > use is_vmware_backdoor_opcode() and from the mere existence of > > EMULTYPE_VMWARE. So I think it’s legit to decide that we will just move all > > the VMware interception logic into the x86 emulator. Including handling > > emulation failures. But then, I would make this patch of yours to also > > modify handle_emulation_failure() to queue #GP to guest directly instead of > > #GP intercept in VMX/SVM to do so. I see you do it in a later patch "KVM: > > x86: Move #GP injection for VMware into x86_emulate_instruction()" but I > > think this should just be squashed with this patch to make sense. > > > > To sum-up, I agree with your approach but I recommend you squash this patch > > and patch 6 of the series to one and change commit message to explain that > > you just move entire handling of VMware interception into the x86 emulator. > > Instead of providing explanations such as VMware emulation is the only one > > that use “no #UD on fail”. > > After reading patch 5 as-well, I would recommend to first apply patch 5 > (filter out #GP with error-code != 0) and only then apply 4+6. Works for me.