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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 63D72C43334 for ; Tue, 19 Jul 2022 18:55:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239307AbiGSSzK (ORCPT ); Tue, 19 Jul 2022 14:55:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49700 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230249AbiGSSzH (ORCPT ); Tue, 19 Jul 2022 14:55:07 -0400 Received: from mail-pg1-x536.google.com (mail-pg1-x536.google.com [IPv6:2607:f8b0:4864:20::536]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 09278F7B for ; Tue, 19 Jul 2022 11:55:06 -0700 (PDT) Received: by mail-pg1-x536.google.com with SMTP id r186so14312670pgr.2 for ; Tue, 19 Jul 2022 11:55:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=ivVC9EM9jM66mJwYdCa12X2ciIU5HLlT0VikbwcqW18=; b=MnT5x6BW+UKIQ9tTlvQG7AAUoEnxPFr6NnmrcUd/RurtAKZFDIiMg5JUfsF3geEtkf ZrZGcTGi12Q0VNsAJrY+9AnTQZiZJwJ3FvhtI+E7NDJBKG95qboQwkRYn/fYPh05sQb0 he9T+4zweUVHob4/7oBcwbOqOdd5JOyMuFsRnle91Go/rjAErLuaVhk45YK1Hlpt/x6u atHackoDC6xIcsPJReC4pjUWkdBX+hE5s/0GiV8ZzL1OlgNu3sEvrmtpaZH3b+DPRJgZ XxBE9rBrogIyvNj/R5TQAAUHa6Yik8hM/f1v0kU2DrBw+rqgyJazV0cgCARTGeIGw9Ol bxQw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=ivVC9EM9jM66mJwYdCa12X2ciIU5HLlT0VikbwcqW18=; b=vKeccXWs4WFsPAs+nvSkwEIWCBqpjzICP6J/sBgVJFDYpvwWB5jLlXDzaKP2KLscZo MKwjXC1oxE/bnbmHuVpPSHkvmA8BBholcizPpfZJs5KnNpv8fv9MQBVVKOy6R3xD6Vc4 I+2rDf7AR8Dg816lewFcw6JygmRNSS2OFVRFGHaMhs3tvZA9dFbgbfVaH1RSLJgw0LAq Cqw5prxYPaDRN4/YToUP1sHHZoo4G6ZVgNIRo/n6rQsgXB/18jqx+rprfJdIsZ9BpUr4 GZ0Ur/7S3W5JkzR85ien2liE6a+blgJn4aGLRDRe/DhU+sK5mntZaE50Pv+xksRv25q8 0idw== X-Gm-Message-State: AJIora/XvC/XFuwfLRyuALsNRGSAExy7NktlDr3EN2YPcZqUaRd4beAO /wTSeP8ktbJe5e0/H6NEV6m+5g== X-Google-Smtp-Source: AGRyM1uBI1w+9Wit78V4mJ9Xfvp+eS4Z/zhmPnP8YfL9Lneiu0bXaLfHGedZMlFDpPHBVaepTaV92Q== X-Received: by 2002:a05:6a00:1daa:b0:52a:c51d:d36a with SMTP id z42-20020a056a001daa00b0052ac51dd36amr34595993pfw.61.1658256904800; Tue, 19 Jul 2022 11:55:04 -0700 (PDT) Received: from google.com (123.65.230.35.bc.googleusercontent.com. [35.230.65.123]) by smtp.gmail.com with ESMTPSA id m5-20020a170902db0500b0016bebb0cb96sm12179765plx.266.2022.07.19.11.55.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 19 Jul 2022 11:55:04 -0700 (PDT) Date: Tue, 19 Jul 2022 18:55:01 +0000 From: Sean Christopherson To: Paolo Bonzini Cc: Aaron Lewis , kvm@vger.kernel.org, jmattson@google.com Subject: Re: [RFC PATCH] KVM: x86: Protect the unused bits in MSR exiting flags Message-ID: References: <20220714161314.1715227-1-aaronlewis@google.com> <8da08a8a-e639-301d-ca98-d85b74c1ad20@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8da08a8a-e639-301d-ca98-d85b74c1ad20@redhat.com> Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Tue, Jul 19, 2022, Paolo Bonzini wrote: > On 7/14/22 18:13, Aaron Lewis wrote: > > --- > > > > Posting as an RFC to get feedback whether it's too late to protect the > > unused flag bits. My hope is this feature is still new enough, and not > > widely used enough, and this change is reasonable enough to be able to be > > corrected. These bits should have been protected from the start, but > > unfortunately they were not. > > > > Another option would be to correct this by adding a quirk, but fixing > > it that has its down sides. It complicates the code more than it > > would otherwise be, and complicates the usage for anyone using any new > > features introduce in the future because they would also have to enable > > a quirk. For long term simplicity my hope is to be able to just patch > > the original change. > > Yes, let's do it this way. Heh, which way is "this way"? (a) Fix KVM_CAP_X86_USER_SPACE_MSR and cross our fingers (b) Add a quirk (c) ???