From patchwork Fri Feb 4 15:53:32 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Claudio Imbrenda X-Patchwork-Id: 12735243 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 3A2DAC4321E for ; Fri, 4 Feb 2022 15:54:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1376300AbiBDPx7 (ORCPT ); Fri, 4 Feb 2022 10:53:59 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:33446 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1376275AbiBDPx6 (ORCPT ); Fri, 4 Feb 2022 10:53:58 -0500 Received: from pps.filterd (m0098410.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.1.2/8.16.1.2) with SMTP id 214Ex3ZY026908; Fri, 4 Feb 2022 15:53:58 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=from : to : cc : subject : date : message-id : mime-version : content-transfer-encoding; s=pp1; bh=YpgTQDBDbGjlQxCtHfqCSieqvvMVSSt+tcgEqjP9EO0=; b=hbePqrgjm8JoQbXpbPpE9gZilkXJ9d/Dtq4ZfRyqAfUl26vXKKR+bzs7Ovqi3sDTz0Df cmidQ0NG7dJRjmEh1BFV1oWqS5xp62bdWknA2PjnUBmuK7VlOw/nTHUwdf6nq70B3D9z 9WhLRvUBGpG9oKOS5xjsu1sKFqeaLX6JrIdbA4AMPuj2RECMmuFn4KfpkD9xEEcQPN6g p2oFkaAYi7vtD0wqdQS+c8norNBNc+lVyuOkSb7tSV1zveuMUfoKqCcRP7ZQeF97KHYI UEDNf5kC77nME+cx1tn6sK8C52AnK8J7kkVUSWCEGsRKl7nMb/L8QX9czpte6mLUP/bx 3Q== Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com with ESMTP id 3e0qx1gm48-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 04 Feb 2022 15:53:58 +0000 Received: from m0098410.ppops.net (m0098410.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.43/8.16.0.43) with SMTP id 214EveUs005504; Fri, 4 Feb 2022 15:53:57 GMT Received: from ppma03fra.de.ibm.com (6b.4a.5195.ip4.static.sl-reverse.com [149.81.74.107]) by mx0a-001b2d01.pphosted.com with ESMTP id 3e0qx1gm3t-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 04 Feb 2022 15:53:57 +0000 Received: from pps.filterd (ppma03fra.de.ibm.com [127.0.0.1]) by ppma03fra.de.ibm.com (8.16.1.2/8.16.1.2) with SMTP id 214FmmUu006808; Fri, 4 Feb 2022 15:53:55 GMT Received: from b06avi18878370.portsmouth.uk.ibm.com (b06avi18878370.portsmouth.uk.ibm.com [9.149.26.194]) by ppma03fra.de.ibm.com with ESMTP id 3e0r0n60wn-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 04 Feb 2022 15:53:55 +0000 Received: from d06av26.portsmouth.uk.ibm.com (d06av26.portsmouth.uk.ibm.com [9.149.105.62]) by b06avi18878370.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 214FrobO46661910 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 4 Feb 2022 15:53:50 GMT Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 6C56FAE055; Fri, 4 Feb 2022 15:53:50 +0000 (GMT) Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id D98C6AE051; Fri, 4 Feb 2022 15:53:49 +0000 (GMT) Received: from p-imbrenda.bredband2.com (unknown [9.145.8.50]) by d06av26.portsmouth.uk.ibm.com (Postfix) with ESMTP; Fri, 4 Feb 2022 15:53:49 +0000 (GMT) From: Claudio Imbrenda To: kvm@vger.kernel.org Cc: borntraeger@de.ibm.com, frankja@linux.ibm.com, thuth@redhat.com, pasic@linux.ibm.com, david@redhat.com, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, scgl@linux.ibm.com Subject: [PATCH v7 00/17] KVM: s390: pv: implement lazy destroy for reboot Date: Fri, 4 Feb 2022 16:53:32 +0100 Message-Id: <20220204155349.63238-1-imbrenda@linux.ibm.com> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: eMgqntDgHnCgi-0S96kTy9aiS5DwWytK X-Proofpoint-GUID: PWcYP2TWRt5Yoli27Or5qbHzddo7bUjr X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.816,Hydra:6.0.425,FMLib:17.11.62.513 definitions=2022-02-04_07,2022-02-03_01,2021-12-02_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 suspectscore=0 mlxlogscore=999 adultscore=0 mlxscore=0 malwarescore=0 clxscore=1015 impostorscore=0 phishscore=0 lowpriorityscore=0 spamscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2201110000 definitions=main-2202040086 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Previously, when a protected VM was rebooted or when it was shut down, its memory was made unprotected, and then the protected VM itself was destroyed. Looping over the whole address space can take some time, considering the overhead of the various Ultravisor Calls (UVCs). This means that a reboot or a shutdown would take a potentially long amount of time, depending on the amount of used memory. This patchseries implements a deferred destroy mechanism for protected guests. When a protected guest is destroyed, its memory can be cleared in background, allowing the guest to restart or terminate significantly faster than before. There are 2 possibilities when a protected VM is torn down: * it still has an address space associated (reboot case) * it does not have an address space anymore (shutdown case) For the reboot case, two new commands are available for the KVM_S390_PV_COMMAND: KVM_PV_ASYNC_DISABLE_PREPARE: prepares the current protected VM for asynchronous teardown. The current VM will then continue immediately as non-protected. If a protected VM had already been set aside without starting the teardown process, this call will fail. In this case the userspace process should issue a normal KVM_PV_DISABLE KVM_PV_ASYNC_DISABLE: tears down the protected VM previously set aside for asychronous teardown. This PV command should ideally be issued by userspace from a separate thread. If a fatal signal is received (or the process terminates naturally), the command will terminate immediately without completing. The idea is that userspace should first issue the KVM_PV_ASYNC_DISABLE_PREPARE command, and in case of success, create a new thread and issue KVM_PV_ASYNC_DISABLE from there. This also allows for proper accounting of the CPU time needed for the asynchronous teardown. This means that the same address space can have memory belonging to more than one protected guest, although only one will be running, the others will in fact not even have any CPUs. The shutdown case should be dealt with in userspace (e.g. using clone(CLONE_VM)). A module parameter is also provided to disable the new functionality, which is otherwise enabled by default. This should not be an issue since the new functionality is opt-in anyway. This is mainly thought to aid debugging. v6->v7 * moved INIT_LIST_HEAD inside spinlock in patch 1 * improved commit messages in patch 2 * added missing locks in patch 3 * added and expanded some comments in patch 11 * rebased v5->v6 * completely reworked the series * removed kernel thread for asynchronous teardown * added new commands to KVM_S390_PV_COMMAND ioctl v4->v5 * fixed and improved some patch descriptions * added some comments to better explain what's going on * use vma_lookup instead of find_vma * rename is_protected to protected_count since now it's used as a counter v3->v4 * added patch 2 * split patch 3 * removed the shutdown part -- will be a separate patchseries * moved the patch introducing the module parameter v2->v3 * added definitions for CC return codes for the UVC instruction * improved make_secure_pte: - renamed rc to cc - added comments to explain why returning -EAGAIN is ok * fixed kvm_s390_pv_replace_asce and kvm_s390_pv_remove_old_asce: - renamed - added locking - moved to gmap.c * do proper error management in do_secure_storage_access instead of trying again hoping to get a different exception * fix outdated patch descriptions v1->v2 * rebased on a more recent kernel * improved/expanded some patch descriptions * improves/expanded some comments * added patch 1, which prevents stall notification when the system is under heavy load. * rename some members of struct deferred_priv to improve readability * avoid an use-after-free bug of the struct mm in case of shutdown * add missing return when lazy destroy is disabled * add support for OOM notifier Claudio Imbrenda (17): KVM: s390: pv: leak the topmost page table when destroy fails KVM: s390: pv: handle secure storage violations for protected guests KVM: s390: pv: handle secure storage exceptions for normal guests KVM: s390: pv: refactor s390_reset_acc KVM: s390: pv: usage counter instead of flag KVM: s390: pv: add export before import KVM: s390: pv: module parameter to fence lazy destroy KVM: s390: pv: make kvm_s390_cpus_from_pv global KVM: s390: pv: clear the state without memset KVM: s390: pv: add mmu_notifier s390/mm: KVM: pv: when tearing down, try to destroy protected pages KVM: s390: pv: refactoring of kvm_s390_pv_deinit_vm KVM: s390: pv: cleanup leftover protected VMs if needed KVM: s390: pv: asynchronous destroy for reboot KVM: s390: pv: api documentation for asynchronous destroy KVM: s390: pv: add KVM_CAP_S390_PROT_REBOOT_ASYNC KVM: s390: pv: avoid export before import if possible Documentation/virt/kvm/api.rst | 21 ++- arch/s390/include/asm/gmap.h | 38 +++- arch/s390/include/asm/kvm_host.h | 4 + arch/s390/include/asm/mmu.h | 2 +- arch/s390/include/asm/mmu_context.h | 2 +- arch/s390/include/asm/pgtable.h | 20 ++- arch/s390/include/asm/uv.h | 1 + arch/s390/kernel/uv.c | 64 +++++++ arch/s390/kvm/kvm-s390.c | 59 ++++++- arch/s390/kvm/kvm-s390.h | 3 + arch/s390/kvm/pv.c | 259 ++++++++++++++++++++++++++-- arch/s390/mm/fault.c | 22 ++- arch/s390/mm/gmap.c | 156 ++++++++++++++--- include/uapi/linux/kvm.h | 3 + 14 files changed, 606 insertions(+), 48 deletions(-)