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=-6.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 E9328C433E0 for ; Fri, 12 Feb 2021 21:50:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A733264E26 for ; Fri, 12 Feb 2021 21:50:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230240AbhBLVuw (ORCPT ); Fri, 12 Feb 2021 16:50:52 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:24036 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229815AbhBLVuu (ORCPT ); Fri, 12 Feb 2021 16:50:50 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1613166564; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=b6HmAk0e01qdqw5/ti+VXBJEF2HavfImZWnbUgYu3S8=; b=eUXpA27XTvHFdmdLsqNTGA0p6GANawB0Jji41EhHrpAfQv7iFpbV9nmPrOYmlkaKDaX54/ 065YBiv1du/jU87BRe2I/Jr2WUW+S/Zec8x5t+bvxQwh0iJ/hmvgBHo7iXUXuWs5pNl3Tj L+J7VQnjoKIeWq1mMqGwe6bgrZakM2w= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-45-qVDrB6S6N1mHD1QZQDX2Ig-1; Fri, 12 Feb 2021 16:49:21 -0500 X-MC-Unique: qVDrB6S6N1mHD1QZQDX2Ig-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id E95F3107ACE6; Fri, 12 Feb 2021 21:49:19 +0000 (UTC) Received: from gigantic.usersys.redhat.com (helium.bos.redhat.com [10.18.17.132]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 6917A19D9F; Fri, 12 Feb 2021 21:49:19 +0000 (UTC) From: Bandan Das To: Paolo Bonzini Cc: Jim Mattson , kvm list , "Huang2\, Wei" , "Moger\, Babu" Subject: Re: [PATCH 0/3] AMD invpcid exception fix References: <20210211212241.3958897-1-bsd@redhat.com> <9ff537b7-b204-18fd-6c59-bdb712ed7e20@redhat.com> Date: Fri, 12 Feb 2021 16:49:18 -0500 In-Reply-To: <9ff537b7-b204-18fd-6c59-bdb712ed7e20@redhat.com> (Paolo Bonzini's message of "Fri, 12 Feb 2021 22:42:52 +0100") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Paolo Bonzini writes: > On 12/02/21 21:56, Jim Mattson wrote: >>> Not all, we intercept GPs only under a specific condition - just as we >>> do for vmware_backdoor and for the recent amd errata. IMO, I think it's the right >>> tradeoff to make to get guest exceptions right. >> It sounds like I need to get you in my corner to help put a stop to >> all of the incorrect #UDs that kvm is going to be raising in lieu of >> #PF when narrow physical address width emulation is enabled! > > Ahah :) Apart from the question of when you've entered diminishing > returns, one important thing to consider is what the code looks > like. This series is not especially pretty, and that's not your fault. > The whole idea of special decoding for #GP is a necessary evil for the > address-check errata, but is it worth extending it to the corner case > of INVPCID for CPL>0? > Sure, no worries. I will have fond memories of the time I spent extra time on a trivial patch to address Jim's concerns(ofcourse valid!) only to find out now he has changed his mind. Bandan > Paolo