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=-14.0 required=3.0 tests=BAYES_00,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 CCC20C433DB for ; Wed, 10 Mar 2021 15:52:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A9CE464FBC for ; Wed, 10 Mar 2021 15:52:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233149AbhCJPva (ORCPT ); Wed, 10 Mar 2021 10:51:30 -0500 Received: from mail.kernel.org ([198.145.29.99]:54620 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233096AbhCJPvK (ORCPT ); Wed, 10 Mar 2021 10:51:10 -0500 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id CE1D864FB9; Wed, 10 Mar 2021 15:51:09 +0000 (UTC) Received: from 78.163-31-62.static.virginmediabusiness.co.uk ([62.31.163.78] helo=why.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94) (envelope-from ) id 1lK175-000nQG-Kj; Wed, 10 Mar 2021 15:51:07 +0000 Date: Wed, 10 Mar 2021 15:51:06 +0000 Message-ID: <875z1zxb11.wl-maz@kernel.org> From: Marc Zyngier To: Jing Zhang Cc: KVM , KVM ARM , Linux MIPS , KVM PPC , Linux S390 , Linux kselftest , Paolo Bonzini , James Morse , Julien Thierry , Suzuki K Poulose , Will Deacon , Huacai Chen , Aleksandar Markovic , Thomas Bogendoerfer , Paul Mackerras , Christian Borntraeger , Janosch Frank , David Hildenbrand , Cornelia Huck , Claudio Imbrenda , Sean Christopherson , Vitaly Kuznetsov , Jim Mattson , Peter Shier , Oliver Upton , David Rientjes , Emanuele Giuseppe Esposito Subject: Re: [RFC PATCH 3/4] KVM: stats: Add ioctl commands to pull statistics in binary format In-Reply-To: <20210310003024.2026253-4-jingzhangos@google.com> References: <20210310003024.2026253-1-jingzhangos@google.com> <20210310003024.2026253-4-jingzhangos@google.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.1 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 62.31.163.78 X-SA-Exim-Rcpt-To: jingzhangos@google.com, kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu, linux-mips@vger.kernel.org, kvm-ppc@vger.kernel.org, linux-s390@vger.kernel.org, linux-kselftest@vger.kernel.org, pbonzini@redhat.com, james.morse@arm.com, julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com, will@kernel.org, chenhuacai@kernel.org, aleksandar.qemu.devel@gmail.com, tsbogend@alpha.franken.de, paulus@ozlabs.org, borntraeger@de.ibm.com, frankja@linux.ibm.com, david@redhat.com, cohuck@redhat.com, imbrenda@linux.ibm.com, seanjc@google.com, vkuznets@redhat.com, jmattson@google.com, pshier@google.com, oupton@google.com, rientjes@google.com, eesposit@redhat.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org On Wed, 10 Mar 2021 00:30:23 +0000, Jing Zhang wrote: > > Three ioctl commands are added to support binary form statistics data > retrieval. KVM_STATS_GET_INFO, KVM_STATS_GET_NAMES, KVM_STATS_GET_DATA. > KVM_CAP_STATS_BINARY_FORM indicates the capability. > > Signed-off-by: Jing Zhang > --- > virt/kvm/kvm_main.c | 115 ++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 115 insertions(+) > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index 383df23514b9..87dd62516c8b 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -3464,6 +3464,51 @@ static long kvm_vcpu_ioctl(struct file *filp, > r = kvm_arch_vcpu_ioctl_set_fpu(vcpu, fpu); > break; > } > + case KVM_STATS_GET_INFO: { > + struct kvm_stats_info stats_info; > + > + r = -EFAULT; > + stats_info.num_stats = VCPU_STAT_COUNT; > + if (copy_to_user(argp, &stats_info, sizeof(stats_info))) > + goto out; > + r = 0; > + break; > + } > + case KVM_STATS_GET_NAMES: { > + struct kvm_stats_names stats_names; > + > + r = -EFAULT; > + if (copy_from_user(&stats_names, argp, sizeof(stats_names))) > + goto out; > + r = -EINVAL; > + if (stats_names.size < VCPU_STAT_COUNT * KVM_STATS_NAME_LEN) > + goto out; > + > + r = -EFAULT; > + if (copy_to_user(argp + sizeof(stats_names), > + kvm_vcpu_stat_strings, > + VCPU_STAT_COUNT * KVM_STATS_NAME_LEN)) > + goto out; > + r = 0; > + break; > + } > + case KVM_STATS_GET_DATA: { > + struct kvm_stats_data stats_data; > + > + r = -EFAULT; > + if (copy_from_user(&stats_data, argp, sizeof(stats_data))) > + goto out; > + r = -EINVAL; > + if (stats_data.size < sizeof(vcpu->stat)) > + goto out; > + > + r = -EFAULT; > + argp += sizeof(stats_data); > + if (copy_to_user(argp, &vcpu->stat, sizeof(vcpu->stat))) > + goto out; > + r = 0; > + break; > + } > default: > r = kvm_arch_vcpu_ioctl(filp, ioctl, arg); > } > @@ -3695,6 +3740,7 @@ static long kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg) > case KVM_CAP_CHECK_EXTENSION_VM: > case KVM_CAP_ENABLE_CAP_VM: > case KVM_CAP_HALT_POLL: > + case KVM_CAP_STATS_BINARY_FORM: > return 1; > #ifdef CONFIG_KVM_MMIO > case KVM_CAP_COALESCED_MMIO: > @@ -3825,6 +3871,40 @@ static int kvm_vm_ioctl_enable_cap_generic(struct kvm *kvm, > } > } > > +static long kvm_vm_ioctl_stats_get_data(struct kvm *kvm, unsigned long arg) > +{ > + void __user *argp = (void __user *)arg; > + struct kvm_vcpu *vcpu; > + struct kvm_stats_data stats_data; > + u64 *data = NULL, *pdata; > + int i, j, ret = 0; > + size_t dsize = (VM_STAT_COUNT + VCPU_STAT_COUNT) * sizeof(*data); > + > + > + if (copy_from_user(&stats_data, argp, sizeof(stats_data))) > + return -EFAULT; > + if (stats_data.size < dsize) > + return -EINVAL; > + data = kzalloc(dsize, GFP_KERNEL_ACCOUNT); > + if (!data) > + return -ENOMEM; > + > + for (i = 0; i < VM_STAT_COUNT; i++) > + *(data + i) = *((ulong *)&kvm->stat + i); This kind of dance could be avoided if your stats were just an array, or a union of the current data structure and an array. > + > + kvm_for_each_vcpu(j, vcpu, kvm) { > + pdata = data + VM_STAT_COUNT; > + for (i = 0; i < VCPU_STAT_COUNT; i++, pdata++) > + *pdata += *((u64 *)&vcpu->stat + i); Do you really need the in-kernel copy? Why not directly organise the data structures in a way that would allow a bulk copy using copy_to_user()? Another thing is the atomicity of what you are reporting. Don't you care about the consistency of the counters? Thanks, M. -- Without deviation from the norm, progress is not possible.