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 38BCCC43217 for ; Wed, 16 Nov 2022 18:51:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233721AbiKPSvv (ORCPT ); Wed, 16 Nov 2022 13:51:51 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50634 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232097AbiKPSvH (ORCPT ); Wed, 16 Nov 2022 13:51:07 -0500 Received: from mail-pl1-x632.google.com (mail-pl1-x632.google.com [IPv6:2607:f8b0:4864:20::632]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BEC6A49B50 for ; Wed, 16 Nov 2022 10:48:47 -0800 (PST) Received: by mail-pl1-x632.google.com with SMTP id v17so17279608plo.1 for ; Wed, 16 Nov 2022 10:48:47 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=A0w6P3/5rWNmrPimfeWShNgQxfD7eWOB8psbtgB4eNM=; b=iuHU2XySbRBXDBvmb7KGdjsTrJ11MtKm8XUWbJgiH+mJZH0mrNKnmVkYWIqEN8KH+D TMTSgskSxS+dz6pqJQ/6lU5YOrdG2ZlIZWDOaRJRiQwsbQA3PrerGAmObwm4ynhLdSAK ipQyS23YgpxwcwZ6vh4k2Bq/MDUW0MakaENRTi4n4z7trqezhQAU1VBvvRliz6hMutEA 9nByJ3f7EiBHZeDsD30/pNhrYplPoCDi15C49ph/4Z5Ug6emFwiauN/3keUjTSc8xjjS 9rhI8o2gCdwKZQMaSLBrQFcQ5PC0p5wqf3PICwkpXgJE4dUBiCSgdG/Zg1bcsS/uJXqa 0yLg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=A0w6P3/5rWNmrPimfeWShNgQxfD7eWOB8psbtgB4eNM=; b=Xvpy0V+yjeQE6rBv8ny8z0DRfqbcj5k+R5BEWUN3UWwOXoCAtKpWwlVZBkn9K5mBy3 GL2/eIb5xxgoUsgPr8RTH5Cus8Z0auYsZ/qpQ+Drw3pbgvEQ3pYWEDpz8oVh/PVu6E4O zEo4t2JxVFx3VTBtTNdeHEzvBD6kYAJvnSOTH+nL5j/NtZ9mKNR9FdCIGs+lo2mJMKQH RCRaJpRsHejXcaBxH0NpxPi9cIg+2hr4QNhvt8aQrCcJ8CfPIVkSMgmvXnPCUtufH0dz H76nwOzFNPs4RB8iMxCxdB0PAIMTxZY54FkT/DQ9sfmBoBBwm0AI+NTt27f4WRDHrs2L 9hIg== X-Gm-Message-State: ANoB5plUTd8EownJ4CvyRfPyqLre6TCfaYhSCElw1wylsV1do95uelJy DLSb3QI/IbIugHbroLzX2dyQ0g== X-Google-Smtp-Source: AA0mqf7gsXMWPLCwPxYnb+HvqYNLX3WPvDWV8mKDKQpAZsMJhL2t5iqRN/vftj6zV72w0hUj24psag== X-Received: by 2002:a17:90b:3c0d:b0:20d:478a:9d75 with SMTP id pb13-20020a17090b3c0d00b0020d478a9d75mr5030085pjb.149.1668624527166; Wed, 16 Nov 2022 10:48:47 -0800 (PST) Received: from google.com (7.104.168.34.bc.googleusercontent.com. [34.168.104.7]) by smtp.gmail.com with ESMTPSA id 7-20020a621507000000b0056c0b98617esm11265827pfv.0.2022.11.16.10.48.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 16 Nov 2022 10:48:46 -0800 (PST) Date: Wed, 16 Nov 2022 18:48:43 +0000 From: Sean Christopherson To: Andy Lutomirski Cc: Chao Peng , kvm list , Linux Kernel Mailing List , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, Linux API , linux-doc@vger.kernel.org, qemu-devel@nongnu.org, Paolo Bonzini , Jonathan Corbet , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , the arch/x86 maintainers , "H. Peter Anvin" , Hugh Dickins , Jeff Layton , "J . Bruce Fields" , Andrew Morton , Shuah Khan , Mike Rapoport , Steven Price , "Maciej S . Szmigiero" , Vlastimil Babka , Vishal Annapurve , Yu Zhang , "Kirill A. Shutemov" , "Nakajima, Jun" , Dave Hansen , Andi Kleen , David Hildenbrand , aarcange@redhat.com, ddutile@redhat.com, dhildenb@redhat.com, Quentin Perret , Fuad Tabba , Michael Roth , Michal Hocko , Muchun Song , Wei W Wang Subject: Re: [PATCH v9 3/8] KVM: Add KVM_EXIT_MEMORY_FAULT exit Message-ID: References: <20221025151344.3784230-1-chao.p.peng@linux.intel.com> <20221025151344.3784230-4-chao.p.peng@linux.intel.com> <2e252f4f-7d45-42ac-a88f-fa8045fe3748@app.fastmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2e252f4f-7d45-42ac-a88f-fa8045fe3748@app.fastmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 16, 2022, Andy Lutomirski wrote: > > > On Tue, Oct 25, 2022, at 8:13 AM, Chao Peng wrote: > > diff --git a/Documentation/virt/kvm/api.rst > > b/Documentation/virt/kvm/api.rst > > index f3fa75649a78..975688912b8c 100644 > > --- a/Documentation/virt/kvm/api.rst > > +++ b/Documentation/virt/kvm/api.rst > > @@ -6537,6 +6537,29 @@ array field represents return values. The > > userspace should update the return > > values of SBI call before resuming the VCPU. For more details on > > RISC-V SBI > > spec refer, https://github.com/riscv/riscv-sbi-doc. > > > > +:: > > + > > + /* KVM_EXIT_MEMORY_FAULT */ > > + struct { > > + #define KVM_MEMORY_EXIT_FLAG_PRIVATE (1 << 0) > > + __u32 flags; > > + __u32 padding; > > + __u64 gpa; > > + __u64 size; > > + } memory; > > + > > Would it make sense to also have a field for the access type (read, write, > execute, etc)? I realize that shared <-> private conversion doesn't strictly > need this, but it seems like it could be useful for logging failures and also > for avoiding a second immediate fault if the type gets converted but doesn't > have the right protection yet. I don't think a separate field is necessary, that info can be conveyed via flags. Though maybe we should go straight to a u64 for flags. Hmm, and maybe avoid bits 0-3 so that if/when RWX info is conveyed the flags can align with PROT_{READ,WRITE,EXEC} and the EPT flags, e.g. KVM_MEMORY_EXIT_FLAG_READ (1 << 0) KVM_MEMORY_EXIT_FLAG_WRITE (1 << 1) KVM_MEMORY_EXIT_FLAG_EXECUTE (1 << 2) > (Obviously, if this were changed, KVM would need the ability to report that > it doesn't actually know the mode.) > > --Andy