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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 C34E4C43381 for ; Fri, 1 Mar 2019 09:36:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8D92E2087E for ; Fri, 1 Mar 2019 09:36:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733301AbfCAJf7 (ORCPT ); Fri, 1 Mar 2019 04:35:59 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:44838 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733133AbfCAJf6 (ORCPT ); Fri, 1 Mar 2019 04:35:58 -0500 Received: from pps.filterd (m0098409.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x219T7Z0114306 for ; Fri, 1 Mar 2019 04:35:57 -0500 Received: from e06smtp02.uk.ibm.com (e06smtp02.uk.ibm.com [195.75.94.98]) by mx0a-001b2d01.pphosted.com with ESMTP id 2qy1tk9bwt-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Fri, 01 Mar 2019 04:35:57 -0500 Received: from localhost by e06smtp02.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Fri, 1 Mar 2019 09:35:51 -0000 Received: from d06av25.portsmouth.uk.ibm.com (d06av25.portsmouth.uk.ibm.com [9.149.105.61]) by b06cxnps4074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x219ZnF627525144 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Fri, 1 Mar 2019 09:35:49 GMT Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 75ECB11C054; Fri, 1 Mar 2019 09:35:49 +0000 (GMT) Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E329711C04A; Fri, 1 Mar 2019 09:35:48 +0000 (GMT) Received: from [9.152.224.140] (unknown [9.152.224.140]) by d06av25.portsmouth.uk.ibm.com (Postfix) with ESMTP; Fri, 1 Mar 2019 09:35:48 +0000 (GMT) Reply-To: pmorel@linux.ibm.com Subject: Re: [PATCH v4 5/7] s390: ap: implement PAPQ AQIC interception in kernel To: Christian Borntraeger Cc: alex.williamson@redhat.com, cohuck@redhat.com, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, kvm@vger.kernel.org, frankja@linux.ibm.com, akrowiak@linux.ibm.com, pasic@linux.ibm.com, david@redhat.com, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, freude@linux.ibm.com, mimu@linux.ibm.com References: <1550849400-27152-1-git-send-email-pmorel@linux.ibm.com> <1550849400-27152-6-git-send-email-pmorel@linux.ibm.com> From: Pierre Morel Date: Fri, 1 Mar 2019 10:35:48 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 x-cbid: 19030109-0008-0000-0000-000002C66DFC X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19030109-0009-0000-0000-00002232C2C3 Message-Id: <44146ea5-8bdf-e986-6e6d-9cbfc104ba37@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-03-01_08:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=2 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1903010066 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 28/02/2019 21:20, Christian Borntraeger wrote: > > > On 22.02.2019 16:29, Pierre Morel wrote: >> We register the AP PQAP instruction hook during the open >> of the mediated device. And unregister it on release. >> >> In the AP PQAP instruction hook, if we receive a demand to >> enable IRQs, >> - we retrieve the vfio_ap_queue based on the APQN we receive >> in REG1, >> - we retrieve the page of the guest address, (NIB), from >> register REG2 >> - we the mediated device to use the VFIO pinning infratrsucture >> to pin the page of the guest address, >> - we retrieve the pointer to KVM to register the guest ISC >> and retrieve the host ISC >> - finaly we activate GISA >> >> If we receive a demand to disable IRQs, >> - we deactivate GISA >> - unregister from the GIB >> - unping the NIB >> >> Signed-off-by: Pierre Morel >> --- >> arch/s390/include/asm/kvm_host.h | 1 + >> drivers/s390/crypto/ap_bus.h | 1 + >> drivers/s390/crypto/vfio_ap_ops.c | 199 +++++++++++++++++++++++++++++++++- >> drivers/s390/crypto/vfio_ap_private.h | 1 + >> 4 files changed, 199 insertions(+), 3 deletions(-) >> >> diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h >> index 49cc8b0..5f3bb8c 100644 >> --- a/arch/s390/include/asm/kvm_host.h >> +++ b/arch/s390/include/asm/kvm_host.h >> @@ -720,6 +720,7 @@ struct kvm_s390_cpu_model { >> struct kvm_s390_crypto { >> struct kvm_s390_crypto_cb *crycb; >> int (*pqap_hook)(struct kvm_vcpu *vcpu); >> + void *vfio_private; >> __u32 crycbd; >> __u8 aes_kw; >> __u8 dea_kw; >> diff --git a/drivers/s390/crypto/ap_bus.h b/drivers/s390/crypto/ap_bus.h >> index bfc66e4..323f2aa 100644 >> --- a/drivers/s390/crypto/ap_bus.h >> +++ b/drivers/s390/crypto/ap_bus.h >> @@ -43,6 +43,7 @@ static inline int ap_test_bit(unsigned int *ptr, unsigned int nr) >> #define AP_RESPONSE_BUSY 0x05 >> #define AP_RESPONSE_INVALID_ADDRESS 0x06 >> #define AP_RESPONSE_OTHERWISE_CHANGED 0x07 >> +#define AP_RESPONSE_INVALID_GISA 0x08 >> #define AP_RESPONSE_Q_FULL 0x10 >> #define AP_RESPONSE_NO_PENDING_REPLY 0x10 >> #define AP_RESPONSE_INDEX_TOO_BIG 0x11 >> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c >> index 1b5130a..0196065 100644 >> --- a/drivers/s390/crypto/vfio_ap_ops.c >> +++ b/drivers/s390/crypto/vfio_ap_ops.c >> @@ -43,7 +43,7 @@ struct vfio_ap_queue *vfio_ap_get_queue(int apqn, struct list_head *l) >> return NULL; >> } >> >> -static int vfio_ap_mdev_reset_queue(struct vfio_ap_queue *q) >> +int vfio_ap_mdev_reset_queue(struct vfio_ap_queue *q) >> { >> struct ap_queue_status status; >> int retry = 20; >> @@ -75,6 +75,27 @@ static int vfio_ap_mdev_reset_queue(struct vfio_ap_queue *q) >> return -EBUSY; >> } >> >> +/** >> + * vfio_ap_free_irq: >> + * @q: The vfio_ap_queue >> + * >> + * Unpin the guest NIB >> + * Unregister the ISC from the GIB alert >> + * Clear the vfio_ap_queue intern fields >> + */ >> +static void vfio_ap_free_irq(struct vfio_ap_queue *q) >> +{ >> + if (!q) >> + return; >> + if (q->g_pfn) >> + vfio_unpin_pages(mdev_dev(q->matrix_mdev->mdev), &q->g_pfn, 1); >> + if (q->isc) >> + kvm_s390_gisc_unregister(q->matrix_mdev->kvm, q->isc); >> + q->nib = 0; >> + q->isc = 0; >> + q->g_pfn = 0; >> +} > > Pierre, unless there is some magic, I think we need to free the gisa stuff before kvm exit. > > Imagine a malicious userspace that setups everything fine, but then closes all kvm file > descriptors but not the vfio file descriptor. This might result in random access to the > memory that contained the gisa potentially resulting in random memory overwrites. > > the problem is that kvm_destroy_vm calls kvm_arch_destroy_vm(kvm) before it calls > kvm_destroy_devices(kvm); So we already free the gisa before we do the unregister call. > > What about calling kvm_get_kvm/put from some of the callbacks in the right places. > > Debugging random memory overwrites is a PITA, so we either should document why I cannot > happen (even with malicious userspace) or simply fix the refcounting. > OK, understood. I think we can do something simple by using kvm_get/kvm_put, as you suggested, in the vfio KVM notifier to ensure the order of the calls and also unregister the GISA at this moment. I will investigate in this direction. Thanks Pierre -- Pierre Morel Linux/KVM/QEMU in Böblingen - Germany