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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9336CC433EF for ; Mon, 18 Oct 2021 11:44:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 79BEB60F9D for ; Mon, 18 Oct 2021 11:44:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231260AbhJRLqs (ORCPT ); Mon, 18 Oct 2021 07:46:48 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:33518 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230381AbhJRLqq (ORCPT ); Mon, 18 Oct 2021 07:46:46 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1634557475; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=KeixeMV2EogBAUUjIMMzujFC6vH6Vam8STyg+YsaQ90=; b=ennZLZ2zbVuqbnU2WQcbpPwlOolFxXU3thLtbvn8IL9tEB4NJK7J+O58ekD8rKNrNNu2Of 5fDjVO6m042ieOb3QhlHAxXLNZXLvB4RWB5hy0UHbLe7h7nW07NrLwjCHGcGZq0Y0FTETo USeApaqyQmUAZvE5XNz7zUz8D5IYo/U= Received: from mail-wr1-f70.google.com (mail-wr1-f70.google.com [209.85.221.70]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-471-U39hZVvEMhiF4hgBQMhWjA-1; Mon, 18 Oct 2021 07:44:34 -0400 X-MC-Unique: U39hZVvEMhiF4hgBQMhWjA-1 Received: by mail-wr1-f70.google.com with SMTP id f1-20020a5d64c1000000b001611832aefeso8753390wri.17 for ; Mon, 18 Oct 2021 04:44:33 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=KeixeMV2EogBAUUjIMMzujFC6vH6Vam8STyg+YsaQ90=; b=uddRnb8r67DJTFlUKMs5NkdMpGhzYfYxbYfoKrQPLdPChQcjNTKlVF2CrAb3i+Zkgu hVmduDKeNv7kGNFxwsUG+xW3thwcq58PTLOpCpaABSFnxn97o+whBAs3G0Y4Zgn1Vf+w EzON/lqTYwZZjCsbEESCEQND8nK7ats32eJ1kKa214HxdsH1AzFw3urndv4qvpnKp7yD ADNIYbnC8s7qTCpxslKERU7wnCS/Hgx4VaeBlWBHfV1+tBH8Xg3omFzqEWUAEqBCiWaR ZWRGmdCyPFvBKHIFraU3FSAdjI4ENYFfLyxXUPA5xNC8WAh5sDpXT8Ks3XLvOWW9LyZM mcVg== X-Gm-Message-State: AOAM533cqcLo8nWv5jo6rslfLZbvWlaapFWiQqKaX11t5d3mNieR0amF 5zQ4F7AP8ZLJZKb0/juCQ82vKkYYjYaw02sTDari3Xksh5+L0Ytl1q+O55LH0IhyyLec36zbBIw Rh8K6iyXA9vbq1IjT3621SGbG X-Received: by 2002:a1c:9d97:: with SMTP id g145mr29273137wme.78.1634557473026; Mon, 18 Oct 2021 04:44:33 -0700 (PDT) X-Google-Smtp-Source: ABdhPJzM7xblvRzkieqyGQRoyyigfLr3YHi5vClYT5nTsuGDzx7Nn0wiXpFo+D+jMwR3Yhbu5vd0iw== X-Received: by 2002:a1c:9d97:: with SMTP id g145mr29273114wme.78.1634557472776; Mon, 18 Oct 2021 04:44:32 -0700 (PDT) Received: from ?IPV6:2001:b07:6468:f312:c8dd:75d4:99ab:290a? ([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id k6sm12708013wri.83.2021.10.18.04.44.31 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 18 Oct 2021 04:44:32 -0700 (PDT) Message-ID: Date: Mon, 18 Oct 2021 13:44:30 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.1.0 Subject: Re: [PATCH RFC] KVM: SVM: reduce guest MAXPHYADDR by one in case C-bit is a physical bit Content-Language: en-US To: Maxim Levitsky , Sean Christopherson , Vitaly Kuznetsov Cc: kvm@vger.kernel.org, Wanpeng Li , Jim Mattson , Tom Lendacky , David Matlack , linux-kernel@vger.kernel.org References: <20211015150524.2030966-1-vkuznets@redhat.com> From: Paolo Bonzini In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 17/10/21 09:54, Maxim Levitsky wrote: > > I'll say, a hack to reduce it by 1 bit is still better that failing > tests, at least until AMD explains to us, about what is going on. What's going on is documented in the thread at https://yhbt.net/lore/all/4f46f3ab-60e4-3118-1438-10a1e17cd900@suse.com/: > That doesn't really follow what Andrew gave us, namely: > > 1) On parts with <40 bits, its fully hidden from software > > 2) Before Fam17h, it was always 12G just below 1T, even if there was > more RAM above this location > > 3) On Fam17h and later, it is variable based on SME, and is either > just below 2^48 (no encryption) or 2^43 (encryption) If you can use this information to implement the fix, that'd be very nice. I didn't apply the hackish fix because I wanted to test it on a SME-enabled box. Paolo