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=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 31A61C433E0 for ; Wed, 24 Jun 2020 14:50:54 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 05F8020768 for ; Wed, 24 Jun 2020 14:50:53 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 05F8020768 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.ibm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:53148 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jo6jl-00051o-6G for qemu-devel@archiver.kernel.org; Wed, 24 Jun 2020 10:50:53 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:44158) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jo6j8-00046I-RO; Wed, 24 Jun 2020 10:50:14 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:49486) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jo6j6-0006ln-PV; Wed, 24 Jun 2020 10:50:14 -0400 Received: from pps.filterd (m0127361.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 05OEWb9G027966; Wed, 24 Jun 2020 10:50:06 -0400 Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com with ESMTP id 31uwymsja6-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 24 Jun 2020 10:50:06 -0400 Received: from m0127361.ppops.net (m0127361.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.36/8.16.0.36) with SMTP id 05OEWqq5028589; Wed, 24 Jun 2020 10:50:05 -0400 Received: from ppma03wdc.us.ibm.com (ba.79.3fa9.ip4.static.sl-reverse.com [169.63.121.186]) by mx0a-001b2d01.pphosted.com with ESMTP id 31uwymsj7t-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 24 Jun 2020 10:50:04 -0400 Received: from pps.filterd (ppma03wdc.us.ibm.com [127.0.0.1]) by ppma03wdc.us.ibm.com (8.16.0.42/8.16.0.42) with SMTP id 05OEaB8T018530; Wed, 24 Jun 2020 14:50:00 GMT Received: from b03cxnp08028.gho.boulder.ibm.com (b03cxnp08028.gho.boulder.ibm.com [9.17.130.20]) by ppma03wdc.us.ibm.com with ESMTP id 31uus1cnw0-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 24 Jun 2020 14:50:00 +0000 Received: from b03ledav004.gho.boulder.ibm.com (b03ledav004.gho.boulder.ibm.com [9.17.130.235]) by b03cxnp08028.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 05OEnxDR27263410 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 24 Jun 2020 14:49:59 GMT Received: from b03ledav004.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 29F7E7805C; Wed, 24 Jun 2020 14:49:59 +0000 (GMT) Received: from b03ledav004.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 23ECC78060; Wed, 24 Jun 2020 14:49:57 +0000 (GMT) Received: from localhost.localdomain (unknown [9.85.198.108]) by b03ledav004.gho.boulder.ibm.com (Postfix) with ESMTPS; Wed, 24 Jun 2020 14:49:57 +0000 (GMT) Subject: Re: [PATCH v3 6/8] s390/sclp: add extended-length sccb support for kvm guest To: Cornelia Huck , Thomas Huth References: <20200618222258.23287-1-walling@linux.ibm.com> <20200618222258.23287-7-walling@linux.ibm.com> <20200624143635.2d87c1ca.cohuck@redhat.com> <20200624145500.69f9ab24.cohuck@redhat.com> From: Collin Walling Message-ID: <7ad94e6b-7e5e-04f6-109a-990075a1d8c2@linux.ibm.com> Date: Wed, 24 Jun 2020 10:49:57 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: <20200624145500.69f9ab24.cohuck@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.216, 18.0.687 definitions=2020-06-24_08:2020-06-24, 2020-06-24 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxlogscore=999 malwarescore=0 priorityscore=1501 impostorscore=0 spamscore=0 bulkscore=0 cotscore=-2147483648 mlxscore=0 clxscore=1015 lowpriorityscore=0 suspectscore=0 phishscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2004280000 definitions=main-2006240106 Received-SPF: pass client-ip=148.163.158.5; envelope-from=walling@linux.ibm.com; helo=mx0b-001b2d01.pphosted.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/06/24 10:50:07 X-ACL-Warn: Detected OS = Linux 3.1-3.10 X-Spam_score_int: -35 X-Spam_score: -3.6 X-Spam_bar: --- X-Spam_report: (-3.6 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: frankja@linux.ibm.com, david@redhat.com, mst@redhat.com, qemu-devel@nongnu.org, pasic@linux.ibm.com, borntraeger@de.ibm.com, qemu-s390x@nongnu.org, svens@linux.ibm.com, pbonzini@redhat.com, mihajlov@linux.ibm.com, rth@twiddle.net Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 6/24/20 8:55 AM, Cornelia Huck wrote: > On Wed, 24 Jun 2020 14:40:58 +0200 > Thomas Huth wrote: > >> On 24/06/2020 14.36, Cornelia Huck wrote: >>> On Thu, 18 Jun 2020 18:22:56 -0400 >>> Collin Walling wrote: >>> >>>> As more features and facilities are added to the Read SCP Info (RSCPI) >>>> response, more space is required to store them. The space used to store >>>> these new features intrudes on the space originally used to store CPU >>>> entries. This means as more features and facilities are added to the >>>> RSCPI response, less space can be used to store CPU entries. >>>> >>>> With the Extended-Length SCCB (ELS) facility, a KVM guest can execute >>>> the RSCPI command and determine if the SCCB is large enough to store a >>>> complete reponse. If it is not large enough, then the required length >>>> will be set in the SCCB header. >>>> >>>> The caller of the SCLP command is responsible for creating a >>>> large-enough SCCB to store a complete response. Proper checking should >>>> be in place, and the caller should execute the command once-more with >>>> the large-enough SCCB. >>>> >>>> This facility also enables an extended SCCB for the Read CPU Info >>>> (RCPUI) command. >>>> >>>> When this facility is enabled, the boundary violation response cannot >>>> be a result from the RSCPI, RSCPI Forced, or RCPUI commands. >>>> >>>> In order to tolerate kernels that do not yet have full support for this >>>> feature, a "fixed" offset to the start of the CPU Entries within the >>>> Read SCP Info struct is set to allow for the original 248 max entries >>>> when this feature is disabled. >>>> >>>> Additionally, this is introduced as a CPU feature to protect the guest >>>> from migrating to a machine that does not support storing an extended >>>> SCCB. This could otherwise hinder the VM from being able to read all >>>> available CPU entries after migration (such as during re-ipl). >>>> >>>> Signed-off-by: Collin Walling >>>> --- >>>> hw/s390x/sclp.c | 21 ++++++++++++++++++++- >>>> include/hw/s390x/sclp.h | 1 + >>>> target/s390x/cpu_features_def.inc.h | 1 + >>>> target/s390x/gen-features.c | 1 + >>>> target/s390x/kvm.c | 8 ++++++++ >>>> 5 files changed, 31 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/hw/s390x/sclp.c b/hw/s390x/sclp.c >>>> index 0dfbe6e5ec..f7c49e339e 100644 >>>> --- a/hw/s390x/sclp.c >>>> +++ b/hw/s390x/sclp.c >>>> @@ -56,6 +56,18 @@ static bool sccb_has_valid_boundary(uint64_t sccb_addr, uint32_t code, >>>> uint64_t sccb_boundary = (sccb_addr & PAGE_MASK) + PAGE_SIZE; >>>> >>>> switch (code & SCLP_CMD_CODE_MASK) { >>>> + case SCLP_CMDW_READ_SCP_INFO: >>>> + case SCLP_CMDW_READ_SCP_INFO_FORCED: >>>> + case SCLP_CMDW_READ_CPU_INFO: >>>> + /* >>>> + * An extended-length SCCB is only allowed for Read SCP/CPU Info and >>>> + * is allowed to exceed the 4k boundary. The respective commands will >>>> + * set the length field to the required length if an insufficient >>>> + * SCCB length is provided. >>>> + */ >>>> + if (s390_has_feat(S390_FEAT_EXTENDED_LENGTH_SCCB)) { >>>> + return true; >>>> + } >>> >>> Add a fallthrough annotation? >> >> ... otherwise Coverity and friends will complain later. > > Nod. > Something simple like... /* without this feature, these commands must respect the 4k boundary */ ? >> >>>> default: >>>> if (sccb_max_addr < sccb_boundary) { >>>> return true; >>>> @@ -72,6 +84,10 @@ static bool sccb_sufficient_len(SCCB *sccb, int num_cpus, int data_len) >>>> >>>> if (be16_to_cpu(sccb->h.length) < required_len) { >>>> sccb->h.response_code = cpu_to_be16(SCLP_RC_INSUFFICIENT_SCCB_LENGTH); >>>> + if (s390_has_feat(S390_FEAT_EXTENDED_LENGTH_SCCB) && >>>> + sccb->h.control_mask[2] & SCLP_VARIABLE_LENGTH_RESPONSE) { >>>> + sccb->h.length = required_len; >>>> + } >>>> return false; >>>> } >>>> return true; >>>> @@ -101,7 +117,9 @@ static void prepare_cpu_entries(MachineState *ms, CPUEntry *entry, int *count) >>>> */ >>>> static inline int get_read_scp_info_data_len(void) >>>> { >>>> - return offsetof(ReadInfo, entries); >>>> + return s390_has_feat(S390_FEAT_EXTENDED_LENGTH_SCCB) ? >>>> + offsetof(ReadInfo, entries) : >>>> + SCLP_READ_SCP_INFO_FIXED_CPU_OFFSET; >>>> } >>>> >>>> /* Provide information about the configuration, CPUs and storage */ >>>> @@ -116,6 +134,7 @@ static void read_SCP_info(SCLPDevice *sclp, SCCB *sccb) >>>> CPUEntry *entries_start = (void *)sccb + data_len; >>>> >>>> if (!sccb_sufficient_len(sccb, machine->possible_cpus->len, data_len)) { >>>> + warn_report("insufficient sccb size to store read scp info response"); >>> >>> Hm, this warning is triggered by a guest action, isn't it? Not sure how >>> helpful it is. >> >> I think this should be qemu_log_mask(LOG_GUEST_ERROR, ...) instead? > > Yes, that sounds better. > > Sure, sounds good. -- Regards, Collin Stay safe and stay healthy