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 3E82DC433EF for ; Fri, 12 Nov 2021 16:52:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 18E316108B for ; Fri, 12 Nov 2021 16:52:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235378AbhKLQzr (ORCPT ); Fri, 12 Nov 2021 11:55:47 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46432 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234342AbhKLQzp (ORCPT ); Fri, 12 Nov 2021 11:55:45 -0500 Received: from mail-pg1-x52f.google.com (mail-pg1-x52f.google.com [IPv6:2607:f8b0:4864:20::52f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2069CC061766 for ; Fri, 12 Nov 2021 08:52:55 -0800 (PST) Received: by mail-pg1-x52f.google.com with SMTP id n23so8489106pgh.8 for ; Fri, 12 Nov 2021 08:52:55 -0800 (PST) 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=zgvW9FuxSDlvjidn6+j+BtBuiiEW1gXL653B7SOOudk=; b=LEi709KrmaL+u/rY618lmBZ0UobYD1L5zZWJ8FoHmc0sk6TXC/sR+p1JhQ9xVSpWqd 8l5ogamsfy3lyD8Cbj3jm8NWnEB3nIuvggCYbKp5fMNqPHC93EKRxygbuho6+wtYIELA yiIcuEaNre/YllRe8cVTn0Iaj6sdDUq81uoL6pyRYe8B2TQs46suqNHeGddNbFWoyWzx 4yfVCp5Q6VYY8Oo9HlfSNpGBDzpNkcsXE7CoDCF6fxS0uq6IW+1Jw4fpGp2tzRnt7xg3 zuZRTQIEgh75a02jmXQTuWMJrj4FhSCY4MwjOW+XGNFkt4+Nwi2Wq5y5NdCICKdEeEf0 ew0g== 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=zgvW9FuxSDlvjidn6+j+BtBuiiEW1gXL653B7SOOudk=; b=4CKFYFYM3lAj6PKSJFig11P7iuPZWg9157nuxdhxq8QGVpjgGABLeq0X1KffDJJ9Ym DdevACiXdA5Ru/y43HpDsKEAZKBwH8FijoDu2o2R1YPqPaqA3wLvJP8p8gqT6NR6mXns tBZZ0Mx3sfEdK0WGdx/LkFvz1FiGuItqlVDyUbzbk48m5fyvtH8whZa0Xkw/o9AM8yQS ak1fqYJj90ArjSIsrdNopMGfD5djvuiM1/r2CcQTLa+RBpIvlxLE1tVr+eLfP5KWUJvf zKk6OMLHtC6eEyJCW7SgdnRGmb+OxTknj+idj7xrmUZsPIMvLO/AwFggfQDuqw5Ag+H6 uMAw== X-Gm-Message-State: AOAM531hy38Jnx/sMFeXAWu+HfYM8zQlGNV7RDkT8cu24DlC4V40vqwf Bqf1lmoCpJ3aRuvC8u4oP3/ZFw== X-Google-Smtp-Source: ABdhPJz++Y6HAiJA+KwLtby7VzO7I5bTXmB/IdEzVJLiqDa/X8dy8+6G8ER2jTixEaeTKqLvOLnKiw== X-Received: by 2002:a05:6a00:148d:b0:49f:def7:9cfe with SMTP id v13-20020a056a00148d00b0049fdef79cfemr15359043pfu.69.1636735974327; Fri, 12 Nov 2021 08:52:54 -0800 (PST) Received: from google.com (157.214.185.35.bc.googleusercontent.com. [35.185.214.157]) by smtp.gmail.com with ESMTPSA id l21sm6784585pfu.213.2021.11.12.08.52.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 12 Nov 2021 08:52:53 -0800 (PST) Date: Fri, 12 Nov 2021 16:52:50 +0000 From: Sean Christopherson To: Xiaoyao Li Cc: Paolo Bonzini , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , erdemaktas@google.com, Connor Kuehl , x86@kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, isaku.yamahata@intel.com, Kai Huang Subject: Re: [PATCH 10/11] KVM: Disallow read-only memory for x86 TDX Message-ID: References: <20211112153733.2767561-1-xiaoyao.li@intel.com> <20211112153733.2767561-11-xiaoyao.li@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211112153733.2767561-11-xiaoyao.li@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Nov 12, 2021, Xiaoyao Li wrote: > From: Isaku Yamahata > > TDX doesn't expose permission bits to the VMM in the SEPT tables, i.e., > doesn't support read-only private memory. > > Introduce kvm_arch_support_readonly_mem(), which returns true except for > x86. x86 has its own implementation based on vm_type that returns faluse > for TDX VM. > > Propagate it to KVM_CAP_READONLY_MEM to allow reporting on a per-VM > basis. Assuming KVM gains support for private memslots (or memslots that _may_ be mapped private), this is incorrect, the restriction on read-only memory only applies to private memory. Userspace should still be allowed to create read-only shared memory. Ditto for dirty-logging in the next patch. When this patch was originally created, it was "correct" because there was no (proposed) concept of a private memslot or of a memslot that can be mapped private. So these two patches at least need to wait until KVM has a defind ABI for managing guest private memory.