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=-8.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 19D02C433E0 for ; Thu, 14 May 2020 07:53:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EF8FF20575 for ; Thu, 14 May 2020 07:53:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Ydfuhws0" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725878AbgENHx0 (ORCPT ); Thu, 14 May 2020 03:53:26 -0400 Received: from us-smtp-2.mimecast.com ([205.139.110.61]:58781 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725886AbgENHx0 (ORCPT ); Thu, 14 May 2020 03:53:26 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1589442804; 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:openpgp:openpgp; bh=TrCBeSqKjO6O1ZTRFPbViol6yVoYxWh8OwTfPgDqwh0=; b=Ydfuhws0HZKse1tC5eJi7mo/JgtxFVKFSS+kzdUYZT7hWoDDfGQ1QfruMv8tKxJoTvQVO+ cAobTl2n8tLh0KIe3TxtRZ/8ogmr0CrTQZAd8vERHCQKsbthpOBNJnHlxe5cdSuNJGOKCn AOn/wC+hM5CYT/42DB70jfJbQr0W3cs= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-358-tuk6MqQPOuC4uMv4Xab4xA-1; Thu, 14 May 2020 03:53:22 -0400 X-MC-Unique: tuk6MqQPOuC4uMv4Xab4xA-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 1BA32107ACF2; Thu, 14 May 2020 07:53:21 +0000 (UTC) Received: from thuth.remote.csb (ovpn-113-31.ams2.redhat.com [10.36.113.31]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 6A9E97529E; Thu, 14 May 2020 07:53:14 +0000 (UTC) Subject: Re: [PATCH v6 2/2] s390/kvm: diagnose 318 handling To: Collin Walling , kvm@vger.kernel.org, linux-s390@vger.kernel.org Cc: pbonzini@redhat.com, borntraeger@de.ibm.com, frankja@linux.ibm.com, david@redhat.com, cohuck@redhat.com, imbrenda@linux.ibm.com, heiko.carstens@de.ibm.com, gor@linux.ibm.com References: <20200513221557.14366-1-walling@linux.ibm.com> <20200513221557.14366-3-walling@linux.ibm.com> From: Thomas Huth Openpgp: preference=signencrypt Message-ID: Date: Thu, 14 May 2020 09:53:12 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <20200513221557.14366-3-walling@linux.ibm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 14/05/2020 00.15, Collin Walling wrote: > DIAGNOSE 0x318 (diag318) is a privileged s390x instruction that must > be intercepted by SIE and handled via KVM. Let's introduce some > functions to communicate between userspace and KVM via ioctls. These > will be used to get/set the diag318 related information, as well as > check the system if KVM supports handling this instruction. > > This information can help with diagnosing the environment the VM is > running in (Linux, z/VM, etc) if the OS calls this instruction. > > By default, this feature is disabled and can only be enabled if a > user space program (such as QEMU) explicitly requests it. > > The Control Program Name Code (CPNC) is stored in the SIE block > and a copy is retained in each VCPU. The Control Program Version > Code (CPVC) is not designed to be stored in the SIE block, so we > retain a copy in each VCPU next to the CPNC. > > Signed-off-by: Collin Walling > --- > Documentation/virt/kvm/devices/vm.rst | 29 +++++++++ > arch/s390/include/asm/kvm_host.h | 6 +- > arch/s390/include/uapi/asm/kvm.h | 5 ++ > arch/s390/kvm/diag.c | 20 ++++++ > arch/s390/kvm/kvm-s390.c | 89 +++++++++++++++++++++++++++ > arch/s390/kvm/kvm-s390.h | 1 + > arch/s390/kvm/vsie.c | 2 + > 7 files changed, 151 insertions(+), 1 deletion(-) [...] > diff --git a/arch/s390/kvm/diag.c b/arch/s390/kvm/diag.c > index 563429dece03..3caed4b880c8 100644 > --- a/arch/s390/kvm/diag.c > +++ b/arch/s390/kvm/diag.c > @@ -253,6 +253,24 @@ static int __diag_virtio_hypercall(struct kvm_vcpu *vcpu) > return ret < 0 ? ret : 0; > } > > +static int __diag_set_diag318_info(struct kvm_vcpu *vcpu) > +{ > + unsigned int reg = (vcpu->arch.sie_block->ipa & 0xf0) >> 4; > + u64 info = vcpu->run->s.regs.gprs[reg]; > + > + if (!vcpu->kvm->arch.use_diag318) > + return -EOPNOTSUPP; > + > + vcpu->stat.diagnose_318++; > + kvm_s390_set_diag318_info(vcpu->kvm, info); > + > + VCPU_EVENT(vcpu, 3, "diag 0x318 cpnc: 0x%x cpvc: 0x%llx", > + vcpu->kvm->arch.diag318_info.cpnc, > + (u64)vcpu->kvm->arch.diag318_info.cpvc); > + > + return 0; > +} > + > int kvm_s390_handle_diag(struct kvm_vcpu *vcpu) > { > int code = kvm_s390_get_base_disp_rs(vcpu, NULL) & 0xffff; > @@ -272,6 +290,8 @@ int kvm_s390_handle_diag(struct kvm_vcpu *vcpu) > return __diag_page_ref_service(vcpu); > case 0x308: > return __diag_ipl_functions(vcpu); > + case 0x318: > + return __diag_set_diag318_info(vcpu); > case 0x500: > return __diag_virtio_hypercall(vcpu); I wonder whether it would make more sense to simply drop to userspace and handle the diag 318 call there? That way the userspace would always be up-to-date, and as we've seen in the past (e.g. with the various SIGP handling), it's better if the userspace is in control... e.g. userspace could also decide to only use KVM_S390_VM_MISC_ENABLE_DIAG318 if the guest just executed the diag 318 instruction. And you need the kvm_s390_vm_get/set_misc functions anyway, so these could also be simply used by the diag 318 handler in userspace? > default: > diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c > index d05bb040fd42..c3eee468815f 100644 > --- a/arch/s390/kvm/kvm-s390.c > +++ b/arch/s390/kvm/kvm-s390.c > @@ -159,6 +159,7 @@ struct kvm_stats_debugfs_item debugfs_entries[] = { > { "diag_9c_ignored", VCPU_STAT(diagnose_9c_ignored) }, > { "instruction_diag_258", VCPU_STAT(diagnose_258) }, > { "instruction_diag_308", VCPU_STAT(diagnose_308) }, > + { "instruction_diag_318", VCPU_STAT(diagnose_318) }, > { "instruction_diag_500", VCPU_STAT(diagnose_500) }, > { "instruction_diag_other", VCPU_STAT(diagnose_other) }, > { NULL } > @@ -1243,6 +1244,76 @@ static int kvm_s390_get_tod(struct kvm *kvm, struct kvm_device_attr *attr) > return ret; > } > > +void kvm_s390_set_diag318_info(struct kvm *kvm, u64 info) > +{ > + struct kvm_vcpu *vcpu; > + int i; > + > + kvm->arch.diag318_info.val = info; > + > + VM_EVENT(kvm, 3, "SET: CPNC: 0x%x CPVC: 0x%llx", > + kvm->arch.diag318_info.cpnc, kvm->arch.diag318_info.cpvc); > + > + if (sclp.has_diag318) { > + kvm_for_each_vcpu(i, vcpu, kvm) { > + vcpu->arch.sie_block->cpnc = kvm->arch.diag318_info.cpnc; > + } > + } > +} > + > +static int kvm_s390_vm_set_misc(struct kvm *kvm, struct kvm_device_attr *attr) > +{ > + int ret; > + u64 diag318_info; > + > + switch (attr->attr) { > + case KVM_S390_VM_MISC_ENABLE_DIAG318: > + kvm->arch.use_diag318 = 1; > + ret = 0; > + break; Would it make sense to set kvm->arch.use_diag318 = 1 during the first execution of KVM_S390_VM_MISC_DIAG318 instead, so that we could get along without the KVM_S390_VM_MISC_ENABLE_DIAG318 ? > + case KVM_S390_VM_MISC_DIAG318: > + ret = -EFAULT; > + if (!kvm->arch.use_diag318) > + return -EOPNOTSUPP; > + if (get_user(diag318_info, (u64 __user *)attr->addr)) > + break; > + kvm_s390_set_diag318_info(kvm, diag318_info); > + ret = 0; > + break; > + default: > + ret = -ENXIO; > + break; > + } > + return ret; > +} What about a reset of the guest VM? If a user first boots into a Linux kernel that supports diag 318, then reboots and selects a Linux kernel that does not support diag 318? I'd expect that the cpnc / cpnv values need to be cleared here somewhere? Otherwise the information might not be accurate anymore? Thomas