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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 ACDF3C43382 for ; Tue, 25 Sep 2018 19:55:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4CE8220867 for ; Tue, 25 Sep 2018 19:55:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4CE8220867 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727472AbeIZCEo (ORCPT ); Tue, 25 Sep 2018 22:04:44 -0400 Received: from mx1.redhat.com ([209.132.183.28]:38508 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726372AbeIZCEo (ORCPT ); Tue, 25 Sep 2018 22:04:44 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 9E01C3082141; Tue, 25 Sep 2018 19:55:33 +0000 (UTC) Received: from [10.36.116.104] (ovpn-116-104.ams2.redhat.com [10.36.116.104]) by smtp.corp.redhat.com (Postfix) with ESMTP id 012B25C8A7; Tue, 25 Sep 2018 19:55:26 +0000 (UTC) Subject: Re: [PATCH v10 11/26] s390: vfio-ap: implement mediated device open callback To: Tony Krowiak , Tony Krowiak , linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: freude@de.ibm.com, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, borntraeger@de.ibm.com, cohuck@redhat.com, kwankhede@nvidia.com, bjsdjshi@linux.vnet.ibm.com, pbonzini@redhat.com, alex.williamson@redhat.com, pmorel@linux.vnet.ibm.com, alifm@linux.vnet.ibm.com, mjrosato@linux.vnet.ibm.com, jjherne@linux.vnet.ibm.com, thuth@redhat.com, pasic@linux.vnet.ibm.com, berrange@redhat.com, fiuczy@linux.vnet.ibm.com, buendgen@de.ibm.com, frankja@linux.ibm.com References: <1536781396-13601-1-git-send-email-akrowiak@linux.vnet.ibm.com> <1536781396-13601-12-git-send-email-akrowiak@linux.vnet.ibm.com> <09a6b9e5-e335-14cf-debd-de0f92dafd5e@redhat.com> <69b5e3d3-5d44-37c0-ca10-720345852134@redhat.com> <1a457c48-35f3-cb73-4db8-d3b50a82f211@linux.ibm.com> From: David Hildenbrand Openpgp: preference=signencrypt Autocrypt: addr=david@redhat.com; prefer-encrypt=mutual; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwX4EEwECACgFAljj9eoCGwMFCQlmAYAGCwkI BwMCBhUIAgkKCwQWAgMBAh4BAheAAAoJEE3eEPcA/4Na5IIP/3T/FIQMxIfNzZshIq687qgG 8UbspuE/YSUDdv7r5szYTK6KPTlqN8NAcSfheywbuYD9A4ZeSBWD3/NAVUdrCaRP2IvFyELj xoMvfJccbq45BxzgEspg/bVahNbyuBpLBVjVWwRtFCUEXkyazksSv8pdTMAs9IucChvFmmq3 jJ2vlaz9lYt/lxN246fIVceckPMiUveimngvXZw21VOAhfQ+/sofXF8JCFv2mFcBDoa7eYob s0FLpmqFaeNRHAlzMWgSsP80qx5nWWEvRLdKWi533N2vC/EyunN3HcBwVrXH4hxRBMco3jvM m8VKLKao9wKj82qSivUnkPIwsAGNPdFoPbgghCQiBjBe6A75Z2xHFrzo7t1jg7nQfIyNC7ez MZBJ59sqA9EDMEJPlLNIeJmqslXPjmMFnE7Mby/+335WJYDulsRybN+W5rLT5aMvhC6x6POK z55fMNKrMASCzBJum2Fwjf/VnuGRYkhKCqqZ8gJ3OvmR50tInDV2jZ1DQgc3i550T5JDpToh dPBxZocIhzg+MBSRDXcJmHOx/7nQm3iQ6iLuwmXsRC6f5FbFefk9EjuTKcLMvBsEx+2DEx0E UnmJ4hVg7u1PQ+2Oy+Lh/opK/BDiqlQ8Pz2jiXv5xkECvr/3Sv59hlOCZMOaiLTTjtOIU7Tq 7ut6OL64oAq+zsFNBFXLn5EBEADn1959INH2cwYJv0tsxf5MUCghCj/CA/lc/LMthqQ773ga uB9mN+F1rE9cyyXb6jyOGn+GUjMbnq1o121Vm0+neKHUCBtHyseBfDXHA6m4B3mUTWo13nid 0e4AM71r0DS8+KYh6zvweLX/LL5kQS9GQeT+QNroXcC1NzWbitts6TZ+IrPOwT1hfB4WNC+X 2n4AzDqp3+ILiVST2DT4VBc11Gz6jijpC/KI5Al8ZDhRwG47LUiuQmt3yqrmN63V9wzaPhC+ xbwIsNZlLUvuRnmBPkTJwwrFRZvwu5GPHNndBjVpAfaSTOfppyKBTccu2AXJXWAE1Xjh6GOC 8mlFjZwLxWFqdPHR1n2aPVgoiTLk34LR/bXO+e0GpzFXT7enwyvFFFyAS0Nk1q/7EChPcbRb hJqEBpRNZemxmg55zC3GLvgLKd5A09MOM2BrMea+l0FUR+PuTenh2YmnmLRTro6eZ/qYwWkC u8FFIw4pT0OUDMyLgi+GI1aMpVogTZJ70FgV0pUAlpmrzk/bLbRkF3TwgucpyPtcpmQtTkWS gDS50QG9DR/1As3LLLcNkwJBZzBG6PWbvcOyrwMQUF1nl4SSPV0LLH63+BrrHasfJzxKXzqg rW28CTAE2x8qi7e/6M/+XXhrsMYG+uaViM7n2je3qKe7ofum3s4vq7oFCPsOgwARAQABwsFl BBgBAgAPBQJVy5+RAhsMBQkJZgGAAAoJEE3eEPcA/4NagOsP/jPoIBb/iXVbM+fmSHOjEshl KMwEl/m5iLj3iHnHPVLBUWrXPdS7iQijJA/VLxjnFknhaS60hkUNWexDMxVVP/6lbOrs4bDZ NEWDMktAeqJaFtxackPszlcpRVkAs6Msn9tu8hlvB517pyUgvuD7ZS9gGOMmYwFQDyytpepo YApVV00P0u3AaE0Cj/o71STqGJKZxcVhPaZ+LR+UCBZOyKfEyq+ZN311VpOJZ1IvTExf+S/5 lqnciDtbO3I4Wq0ArLX1gs1q1XlXLaVaA3yVqeC8E7kOchDNinD3hJS4OX0e1gdsx/e6COvy qNg5aL5n0Kl4fcVqM0LdIhsubVs4eiNCa5XMSYpXmVi3HAuFyg9dN+x8thSwI836FoMASwOl C7tHsTjnSGufB+D7F7ZBT61BffNBBIm1KdMxcxqLUVXpBQHHlGkbwI+3Ye+nE6HmZH7IwLwV W+Ajl7oYF+jeKaH4DZFtgLYGLtZ1LDwKPjX7VAsa4Yx7S5+EBAaZGxK510MjIx6SGrZWBrrV TEvdV00F2MnQoeXKzD7O4WFbL55hhyGgfWTHwZ457iN9SgYi1JLPqWkZB0JRXIEtjd4JEQcx +8Umfre0Xt4713VxMygW0PnQt5aSQdMD58jHFxTk092mU+yIHj5LeYgvwSgZN4airXk5yRXl SE+xAvmumFBY Organization: Red Hat GmbH Message-ID: <76ee84e1-e7a7-10bf-ade1-008e48cba0ad@redhat.com> Date: Tue, 25 Sep 2018 21:55:26 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.0 MIME-Version: 1.0 In-Reply-To: <1a457c48-35f3-cb73-4db8-d3b50a82f211@linux.ibm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.42]); Tue, 25 Sep 2018 19:55:33 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 25/09/2018 21:54, Tony Krowiak wrote: > On 09/24/2018 03:55 PM, David Hildenbrand wrote: >> On 24/09/2018 21:46, Tony Krowiak wrote: >>> On 09/24/2018 02:40 PM, David Hildenbrand wrote: >>>> On 24/09/2018 18:07, Tony Krowiak wrote: >>>>> On 09/24/2018 04:40 AM, David Hildenbrand wrote: >>>>>> >>>>>>> /** >>>>>>> - * Verify that the AP instructions are available on the guest. This is >>>>>>> indicated >>>>>>> - * via the KVM_S390_VM_CPU_FEAT_AP CPU model feature. >>>>>>> + * Verify that the AP instructions are being interpreted by firmware >>>>>>> for the >>>>>>> + * guest. This is indicated by the kvm->arch.crypto.apie flag. >>>>>>> */ >>>>>>> static int kvm_ap_validate_crypto_setup(struct kvm *kvm) >>>>>>> { >>>>>>> - if (test_bit_inv(KVM_S390_VM_CPU_FEAT_AP, kvm->arch.cpu_feat)) >>>>>>> + if (kvm->arch.crypto.apie) >>>>>>> return 0; >>>>>> >>>>>> I wonder if this check makes sense, because apie can be toggled during >>>>>> runtime. I guess it would be sufficient to check if the ap control block >>>>>> is available and apie is supported by the HW. >>>>> >>>>> I am not clear about what you are getting at here, but I'll attempt >>>>> to respond. There is no need to check if the AP control block (CRYCB) >>>>> is available as the address is set in the CRYCBD three instructions >>>>> above, even if AP instructions are not available. Regarding whether apie >>>>> is supported by the hardware, the value of vcpu->kvm->arch.crypto.apie >>>>> can not be set unless it is supported by the HW. In the patch (24/26) >>>>> that provides the VM attributes to toggle this value, it can only be >>>>> turned on if the AP instructions are available. I might also note that >>>>> the kvm_ap_validate_crypto_setup() function is called whenever one of >>>>> the VM crypto attributes is changed, so it makes sense that decisions >>>>> made in this function are based on a change to a VM crypto attribute. In >>>>> my first pass at changing this function, I checked >>>>> ap_instructions_available() here, but after considering all of the >>>>> above, it made sense to me to check the apie flag. >>>>> >>>> >>>> I prefer ap_instructions_available(). As I said, kvm->arch.crypto.apie >>>> is a moving target. >>> >>> Looking at this again, I think I responded before my brain shifted from >>> digesting comments about patch 24/26 (enable/disable APIE) to the >>> context for your comment here; namely, the device open callback. My >>> comment above makes no sense in this context. From the perspective of >>> the vfio_ap device driver, there is one requirement that must be met in >>> order to provide pass-through functionality: The AP instructions must be >>> must be interpreted by the HW (i.e., ECA.28 == 1). Checking whether AP >>> instructions are available does not tell us whether they are being >>> interpreted by HW. Checking whether the AP control block (i.e., CRYCB) >>> is available, even when combined with the instruction availability >>> check, does not provide any more insight into the value of ECA.28 >>> becuase the CRYCB will be provided if the MSAX3 facility is installed >>> (STFLE.76) for the guest regardless of whether AP instructions are >>> available or not. There is no doubt that if the AP instructions are >>> not available, then the mdev open callback should fail, but it doesn't >>> tell the whole story. >>> >>> I realize that our CPU model protects against configuring a vfio-ap >>> device for the guest if ap=off, but this function knows nothing about >>> userspace. I can make a similar argument that kvm->arch.crypto.apie >>> will be switched on only if ap=on but again, that is userspace >>> configuration. >>> >>> Having said all of the above, maybe it doesn't really matter whether >>> AP instructions are being interpreted or not. If ECA.28 == 0, then >>> the AP masks may very well be ignored since all AP instructions will >>> be intercepted; so, maybe checking AP instruction availability is all >>> that is needed. I will verify this and if I'm correct, I'll make the >>> change you suggested. >> >> Yes, that was exactly what I had in mind - we just have to make sure >> that the ap control block exists, so we can set the right mask bits. If >> QEMU asks for an intercept, it shall get an intercept. >> >> But please proceed with whatever you think is best! > > After discussing this with Halil, here's what I decided: > * There will be no check for kvm->arch.crypto.apie here > * A check for ap_instructions_available() will not be executed > here, but inserted into the vfio_ap module init function. > The module init function will fail (ENODEV) if the AP > instructions are not installed. In my (our) opinion that > makes more sense given the purpose of the vfio_ap driver is > to pass through the AP instructions to the guest. > * A check will be added here to verify the CRYCB is available (i.e., > matrix_mdev->kvm->arch.crypto.crycbd != 0). > Sounds good to me! -- Thanks, David / dhildenb