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=-10.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 122AFC4338F for ; Fri, 6 Aug 2021 11:39:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EE59E60FE7 for ; Fri, 6 Aug 2021 11:39:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242938AbhHFLj1 (ORCPT ); Fri, 6 Aug 2021 07:39:27 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:26248 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238926AbhHFLj1 (ORCPT ); Fri, 6 Aug 2021 07:39:27 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1628249951; 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=6CCTGCsVlejSWa2TDvN4nfZAMgKaHGMDw5CATIJdm6E=; b=MYSwsJJGQpbfSg2leZGA4AF/cpFPNysJ6v+NXf7RXuzoMHnTStWatKg5F2i/JfXTccBu/0 uanVwSioqLHgFQWrkfhwggRNfOA2z2zofzVvauu+2rdVA2haX3GPeKbwqMDMiAcwtJFcGG PXSwO7BDPavNY85m8FqrmmZao925ydM= Received: from mail-wm1-f71.google.com (mail-wm1-f71.google.com [209.85.128.71]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-166-MtTDi_Z6Ogy2Ea3Il2PeTw-1; Fri, 06 Aug 2021 07:39:10 -0400 X-MC-Unique: MtTDi_Z6Ogy2Ea3Il2PeTw-1 Received: by mail-wm1-f71.google.com with SMTP id l19-20020a05600c4f13b029025b036c91c6so1933198wmq.2 for ; Fri, 06 Aug 2021 04:39:09 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:organization :message-id:date:user-agent:mime-version:in-reply-to :content-language:content-transfer-encoding; bh=6CCTGCsVlejSWa2TDvN4nfZAMgKaHGMDw5CATIJdm6E=; b=omszR190UGDq7hcJAJa13LkMVRkvBMOe3JOqEuWzeUVnw3vD3UJnNer+kWWPlpAQdM fgbNo4N1eXrQecGx5AI32uzs+qUFmpK/n70LJd9Cn5/WL/YlLciYwiIVojgExzFXnKps Q0e4DjSP9mVf4H5k8bp2cLXLlTxnCbNdTj/z2CH5JgasVFBgGDMsQ66miCwz4m+y3TAf Qf0N5nCw+mQk56DVr78+QXFE9UB4GUHfwDIJv2ANb32klUmOkzG48nf9YMh6orYbEALa cXl2km+3mlo3EFiOCtKI+igZIHGRZbqAq0uyVX3iXfoaMbaFwcwOO9yYcFV5u1oPAHb0 VBgg== X-Gm-Message-State: AOAM531C5lUnLeHgxzCPHuZX36WFdcYJ9fLoX+UF44w/qgPFIxO/TdMa ZpNMhVSaoxtturakh8oOOd/NVto2zRh9YACUjWLFRZTUjWHvRkCv67wfIVWsFurhiFGKIFjmZ4h cYopY3aP8/HWPJ8J1oIgDjg== X-Received: by 2002:a05:600c:35c1:: with SMTP id r1mr2807883wmq.101.1628249948973; Fri, 06 Aug 2021 04:39:08 -0700 (PDT) X-Google-Smtp-Source: ABdhPJyBopaYdlFz12anxgFBxd76mmz9lAC4I8VKP8fU5XI5T+hbGBeAtWlQNXOP+dSKFRa9bqFXqA== X-Received: by 2002:a05:600c:35c1:: with SMTP id r1mr2807863wmq.101.1628249948780; Fri, 06 Aug 2021 04:39:08 -0700 (PDT) Received: from [192.168.3.132] (p5b0c6104.dip0.t-ipconnect.de. [91.12.97.4]) by smtp.gmail.com with ESMTPSA id b15sm9184520wrx.73.2021.08.06.04.39.07 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 06 Aug 2021 04:39:08 -0700 (PDT) Subject: Re: [PATCH v3 03/14] KVM: s390: pv: leak the ASCE page when destroy fails To: Claudio Imbrenda Cc: kvm@vger.kernel.org, cohuck@redhat.com, borntraeger@de.ibm.com, frankja@linux.ibm.com, thuth@redhat.com, pasic@linux.ibm.com, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, Ulrich.Weigand@de.ibm.com References: <20210804154046.88552-1-imbrenda@linux.ibm.com> <20210804154046.88552-4-imbrenda@linux.ibm.com> <6b75cc71-b996-cf3d-ce57-dbcd475ebc3a@redhat.com> <20210806113244.4d0712d2@p-imbrenda> From: David Hildenbrand Organization: Red Hat Message-ID: Date: Fri, 6 Aug 2021 13:39:07 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <20210806113244.4d0712d2@p-imbrenda> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-s390@vger.kernel.org On 06.08.21 11:32, Claudio Imbrenda wrote: > On Fri, 6 Aug 2021 09:31:54 +0200 > David Hildenbrand wrote: > >> On 04.08.21 17:40, Claudio Imbrenda wrote: >>> When a protected VM is created, the topmost level of page tables of >>> its ASCE is marked by the Ultravisor; any attempt to use that >>> memory for protected virtualization will result in failure. >>> >>> Only a successful Destroy Configuration UVC will remove the marking. >>> >>> When the Destroy Configuration UVC fails, the topmost level of page >>> tables of the VM does not get its marking cleared; to avoid issues >>> it must not be used again. >>> >>> Since the page becomes in practice unusable, we set it aside and >>> leak it. >> >> Instead of leaking, can't we add it to some list and try again later? >> Or do we only expect permanent errors? > > once the secure VM has been destroyed unsuccessfully, there is nothing > that can be done, this is a permanent error > >> Also, we really should bail out loud (pr_warn) to tell the admin that >> something really nasty is going on. > > when a destroy secure VM UVC fails, there are already other warnings > printed, no need to add one more > Okay, makes sense then to me, thanks! Might be worth adding some of that info to the patch description. -- Thanks, David / dhildenb