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 57FC6C433EF for ; Mon, 15 Nov 2021 15:33:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 439CE63213 for ; Mon, 15 Nov 2021 15:33:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236815AbhKOPge (ORCPT ); Mon, 15 Nov 2021 10:36:34 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:31403 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236639AbhKOPgI (ORCPT ); Mon, 15 Nov 2021 10:36:08 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1636990389; 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=APBRR/Tu29EEMq5VPRu2UikpYWd3k5GAcRpc7iagv8Y=; b=iSq5dZ11iKlabDh5S81yAjysNZaK05j+T/3Db3PfuPoWHz+O2DDtCbLnJNoL5Bmm3bf+e3 PYnvmk2ruRsjVyrFhr6BCYnvHOx9eCpptvzazpmLTWqq1qwvhX6aHMj1O7ax00tAynE1DY t1MJZUC5uszmBAnOmVeBfxEJeB2nF/k= Received: from mail-wm1-f70.google.com (mail-wm1-f70.google.com [209.85.128.70]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-157-NKfOAKyGNb-Cs_NAv18RAQ-1; Mon, 15 Nov 2021 10:33:07 -0500 X-MC-Unique: NKfOAKyGNb-Cs_NAv18RAQ-1 Received: by mail-wm1-f70.google.com with SMTP id o18-20020a05600c511200b00332fa17a02eso61891wms.5 for ; Mon, 15 Nov 2021 07:33:07 -0800 (PST) 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:user-agent; bh=APBRR/Tu29EEMq5VPRu2UikpYWd3k5GAcRpc7iagv8Y=; b=dBMvIrGQBBfhwp8gvgdXyS5MQfCDsydLWTPCEH9WbkXueSKAZeZjn9ttKYHi7YTFfs H3tVohUZ943hLrTi00xYBx3VTCrRaalm0TrKbrLo/gdG5OpBYQw95lk6EArbvFe8Rxcd ACtd4iuieaiEBOQqkveJAmXoEG6F5GkB5zEAeLATsJOLvDGPgZlCbNK4J/RoTcfne72/ efxLYcZjlP6gw7rrdPd/Pxd8DQnVp4CmQ0gIJRvQze9VaH7xv/wCWH5a7AZQprTZalNe LpNbf99ncfheKlXcgCu+UMuXHYNWqrro093UIhf3Qo21F600Zi0Apnz+PtOqMHwnahOP xaZQ== X-Gm-Message-State: AOAM533qKEWrhYetPfpD+JHzszQhIZE9XcyDG0h2uKxK15gRusj4zA/y BN5V2JrtCEEoviBk3QNy6mhvTGCEc2Q3yNvw75MnNDifRo+gf//styMLDSRNwvSrz/pihqSPXbq ovfgklD58KA2i X-Received: by 2002:a1c:f416:: with SMTP id z22mr3828161wma.121.1636990386548; Mon, 15 Nov 2021 07:33:06 -0800 (PST) X-Google-Smtp-Source: ABdhPJzVEfAw7ZxqSyPXBoql05G+DuRg+Mia/ijEWI8l4vzLqLBTzBiaKW9nePq93987lkPciDsGDA== X-Received: by 2002:a1c:f416:: with SMTP id z22mr3828132wma.121.1636990386389; Mon, 15 Nov 2021 07:33:06 -0800 (PST) Received: from work-vm (cpc109025-salf6-2-0-cust480.10-2.cable.virginm.net. [82.30.61.225]) by smtp.gmail.com with ESMTPSA id t8sm17359470wmq.32.2021.11.15.07.33.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 15 Nov 2021 07:33:05 -0800 (PST) Date: Mon, 15 Nov 2021 15:33:03 +0000 From: "Dr. David Alan Gilbert" To: Joerg Roedel Cc: Sean Christopherson , Borislav Petkov , Dave Hansen , Peter Gonda , Brijesh Singh , x86@kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-coco@lists.linux.dev, linux-mm@kvack.org, linux-crypto@vger.kernel.org, Thomas Gleixner , Ingo Molnar , Tom Lendacky , "H. Peter Anvin" , Ard Biesheuvel , Paolo Bonzini , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Andy Lutomirski , Dave Hansen , Sergio Lopez , Peter Zijlstra , Srinivas Pandruvada , David Rientjes , Dov Murik , Tobin Feldman-Fitzthum , Michael Roth , Vlastimil Babka , "Kirill A . Shutemov" , Andi Kleen , tony.luck@intel.com, marcorr@google.com, sathyanarayanan.kuppuswamy@linux.intel.com Subject: Re: [PATCH Part2 v5 00/45] Add AMD Secure Nested Paging (SEV-SNP) Hypervisor Support Message-ID: References: <20210820155918.7518-1-brijesh.singh@amd.com> <061ccd49-3b9f-d603-bafd-61a067c3f6fa@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/2.0.7 (2021-05-04) Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org * Joerg Roedel (jroedel@suse.de) wrote: > On Mon, Nov 15, 2021 at 12:30:59PM +0000, Dr. David Alan Gilbert wrote: > > Still; I wonder if it's best to kill the guest - maybe it's best for > > the host to kill the guest and leave behind diagnostics of what > > happened; for someone debugging the crash, it's going to be less useful > > to know that page X was wrongly accessed (which is what the guest would > > see), and more useful to know that it was the kernel's vhost-... driver > > that accessed it. > > I is best to let the guest #VC on the page when this happens. If it > happened because of a guest bug all necessary debugging data is in the > guest and only the guest owner can obtain it. > > Then the guest owner can do a kdump on this unexpected #VC and collect > the data to debug the issue. With just killing the guest from the host > side this data would be lost. How would you debug an unexpected access by the host kernel using a guests kdump? Dave > Regards, > > Joerg > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK